configs/pic32mx-starterkit README
===============================


This README file discusses the port of NuttX to the Microchip PIC32 Ethernet
Starter Kit (DM320004) with either

  1) The Multimedia Expansion Board (MEB, DM320005), or
  2) The Starter Kit I/O Expansion Board

See www.microchip.com for further information.

The PIC32 Ethernet Starter Kit includes:

- PIC32MX795F512L 32-bit microcontroller.
- PIC32MX795F512L USB microcontroller for on-board debugging.
- Green power indicator LED.
- Orange debug indicator LED.
- Three user-defined indicator LEDs.
- Ethernet 10/100 bus speed indicator LED.
- Three push button switches for user-defined inputs.
- On-board crystal for precision microcontroller clocking (8 MHz).
- 50 MHz Ethernet PHY oscillator.
- 32 kHz oscillator (optional).
- USB connectivity for on-board debugger communications.
- USB Host and OTG power supply for powering PIC32 USB applications.
- USB Type A receptacle connectivity for PIC32 host-based applications.
- USB Type micro-AB receptacle for OTG and USB device connectivity for PIC32
  OTG/device-based applications.
- RJ-45 Ethernet port (External Ethernet PHY).

The MEB adds:

- 3.2 inch (8.1 cm) QVGA touch screen display with backlight
- Solomon Systech Graphics Controller (SSD1926)
- Five user-controlled LEDs
- Power LED
- Four-way joystick
- Fire button
- Headphone jack
- Line output jack
- Microphone input jack
- microSD card slot.
- Accelerometer and temperature sensor
- 24LC08 EEPROM.
- SPI Flash
- 24-bit audio codec
- CPLD for SPI and Chip Select configuration
- Integrated 802.11 wireless connectivity

The Starter Kit I/O Expansion Board:

Mostly just brings out all of the pins from the tiny Starter Kit connector.

Contents
========

  PIC32MX795F512L Pin Out
  MEB Connector
  PICtail
  Serial Output using the
  Toolchains
  Creating Compatible NuttX HEX files
  Serial Console: MEB
  Serial Console: Starter Kit I/O Expansion Board
  LEDs
  PIC32MX Configuration Options
  Configurations

PIC32MX795F512L Pin Out
=======================

LEFT SIDE, TOP-TO-BOTTOM (if pin 1 is in upper left)
--- ---------------------------------- -------------------------- -----------------------------------------------
PIN CONFIGURATIONS                     SIGNAL NAME                ON-BOARD CONNECTIONS
    (Family Data Sheet Table 1-1)     (Starter Kit User Guide)
--- ---------------------------------- -------------------------- -----------------------------------------------
  1 RG15/AERXERR                       ERXERR                     Ethernet RX_ER/MDIX_IN
  2 VDD                                P32_VDD                    ---
  3 PMD5/RE5                           PMPD5/RE5                  J2 pin 13
  4 PMD6/RE6                           PMPD6/RE6                  J2 pin 9
  5 PMD7/RE7                           PMPD7/RE7                  J2 pin 7
  6 RC1/T2CK                           T2CLK/RC1                  J2 pin 35 (timer)
  7 RC2/AC2TX/T3CK                     T3CLK/RC2                  J2 pin 37 (timer)
  8 RC3/AC2RX/T4CK                     T4CLK/RC3                  J2 pin 39 (timer)
  9 RC4/SDI1/T5CK                      SDI1/T4CLK/RC4             J2 pin 41 (timer)
                                                                  J2 pin 93 (SPI1)
 10 PMA5/CN8/ECOL/RG6/SCK2/U3RTS/U6TX  PMPA5/SCM2C/CN8/RG6        J2 pin 45 (SPI2)
                                                                  J2 pin 117 (PMP address)
 11 PMA4/CN9/ECRS/RG7/SDA4/SDI2/U3RX   PMPA4/SCM2A/CN9/RG7        J2 pin 47 (SPI2)
                                                                  J2 pin 119 (PMP address)
 12 PMA3/AECRSDV/AERXDV/CN10/ECRSDV/   ECRS_DV                    Ethernet CRS/CRS_DV/LED_CFG
    ERXDV/RG8/SCL4/SDO2/U3TX
 13 MCLR                               PIC32_MCLR                 (pulled up)
                                                                  PIC32MX440F512H debug processor
                                                                  J2 pin 130 (ICSP)
 14 PMA2/AEREFCLK/AERXCLK/CN11/        EREF_CLK                   50MHz clock, Ethernet X1
    EREFCLK/ERXCLK/RG9/SS2/U3CTS/
    U6RX
 15 VSS                                (grounded)                 ---
 16 VDD                                P32_VDD                    ---
 17 RA0/TMS                            TMS/RA0                    J2 pin 126 (JTAG/GPIO)
 18 AERXD0/INT1/RE8                    ERXD0(2)                   Ethernet RXD_0/PHYAD1
 19 AERXD1/INT2/RE9                    ERXD1(2)                   Ethernet RXD_1/PHYAD2
 20 AN5/C1IN+/CN7/RB5/VBUSON           VBUSON/C1IN+/AN5/CN7/RB5   USB host power supply, TPS20x1B ~EN,
                                                                  Low enables power to host port (J4)
                                                                  USB OTG power supply, MCP1253_MSOP ~SHDN
                                                                  Enables power to device/OTG port (J5)
                                                                  J2 pin 63 (comparator 1)
                                                                  J2 pin 62 (A/D)
 21 AN4/C1IN-/CN6/RB4                  USBOEN/C1IN-/AN4/CN6/RB4   J2 pin 65 (comparator 1)
                                                                  J2 pin 64 (A/D)
 22 AN3/C2IN+/CN5/RB3                  C2IN+/AN3/CN5/RB3          TPS20x1B ~OC, sense host port power
                                                                  MCP1253_MSOP PGOOD, sense device/OTG port power
                                                                  J2 pin 67 (comparator 2)
                                                                  J2 pin 66 (A/D)
 23 AN2/C2IN-/CN4/RB2                  C2IN-/AN2/CN4/RB2          J2 pin 69 (comparator 2)
                                                                  J2 pin 101
                                                                  J2 pin 68 (A/D)
 24 AN1/CN3/PGEC1/RB1                  PGC1/AN1/CN3/RB1           J2 pin 70 (A/D)
 25 AN0/CN2/PGED1/RB0                  PGD1/AN0/CN2/RB0           J2 pin 72 (A/D)

BOTTOM SIDE, LEFT-TO-RIGHT (if pin 1 is in upper left)
--- ---------------------------------- -------------------------- -----------------------------------------------
PIN CONFIGURATIONS                     SIGNAL NAME                ON-BOARD CONNECTIONS
    (Family Data Sheet Table 1-1)     (Starter Kit User Guide)
--- ---------------------------------- -------------------------- -----------------------------------------------
 26 AN6/OCFA/PGEC2/RB6                 PIC32_PGC2                 PIC32MX440F512H debug processor
                                                                  J2 pin 128 (ICSP)
 27 AN7/PGED2/RB7                      PIC32_PGD2/DBG_SD0         PIC32MX440F512H debug processor
                                                                  J2 pin 132 (ICSP)
 28 PMA7/AERXD2/CVREF-/RA9             PMPA7/VREF-/RA9            J2 pin 113 (PMP address)
                                                                  J2 pin 114 (A/D ref)
 29 PMA6/AERXD3/CVREF+/RA10/VREF+      PMPA6/VREF+/RA10           J2 pin 115 (PMP address)
                                                                  J2 pin 116 (A/D ref)
 30 AVDD                               P32_VDD                    ---
 31 AVSS                               (grounded)                 ---
 32 AN8/C1OUT/RB8                      C1OUT/AN8/RB8              J2 pin 71
 33 AN9/C2OUT/RB9                      C2OUT/AN9/RB9              J2 pin 73
 34 PMA13/AN10/RB10/CVREFOUT           PMPA13/CVREF/AN10          J2 pin 101 (PMP address)
                                                                  J2 pin 102 (Comparator ref)
 35 PMA12/AETXERR/AN11/ERXERR/RB11     PMPA12/AN11/RB11           J2 pin 103 (PMP address)
 36 VSS                                (grounded)                 ---
 37 VDD                                P32_VDD                    ---
 38 RA1/TCK                            TCK/RA1                    PIC32MX440F512H debug processor
                                                                  J2 pin 124 (JTAG/GPIO)
 39 AC1TX/RF13/SCK4/U2RTS/U5TX         SCM3D/BCLK2/RF13           J2 pin 106 (UART2)
 40 AC1RX/RF12/SS4/U2CTS/U5RX          SCM3C/RF12                 J2 pin 108 (UART2)
 41 PMA11/AECRS/AN12/ERXD0/RB12        PMPA11/AN12/RB12           J2 pin 105 (PMP address)
 42 PMA10/AECOL/AN13/ERXD1/RB13        PMPA10/AN13/RB13           J2 pin 107 (PMP address)
 43 PMA1/AETXD3/AN14/ERXD2/PMALH/RB14  PMPA1/AN14/RB14            J2 pin 127 (PMP address)
 44 PMA0/AETXD2/AN15/CN12/ERXD3/OCFB/  PMPA0/AN15/OCFB/CN12       J2 pin 129 (PMP address)
    PMALL/RB15                                                    J2 pin 36
 45 VSS                                (grounded)                 ---
 46 VDD                                P32_VDD                    ---
 47 AETXD0/CN20/RD14/SS3/U1CTS/U4RX    EXTD0(2)                   Ethernet TXD_0
 48 AETXD1/CN21/RD15/SCK3/U1RTS/U4TX   EXTD1(2)                   Ethernet TXD_1
 49 PMA9/CN17/RF4/SDA5/SDI4/U2RX       PMPA9/SCM3A/CN17/RF4       J2 pin 109 (PMP address)
                                                                  J2 pin 110 (UART2)
 50 PMA8/CN18/RF5/SCL5/SDO4/U2TX       PMPA8/SCM3B/CN18/RF5       J2 pin 111 (PMP address)
                                                                  J2 pin 112 (UART2)

RIGHT SIDE, TOP-TO-BOTTOM (if pin 1 is in upper left)
--- ---------------------------------- -------------------------- -----------------------------------------------
PIN CONFIGURATIONS                     SIGNAL NAME                ON-BOARD CONNECTIONS
    (Family Data Sheet Table 1-1)     (Starter Kit User Guide)
--- ---------------------------------- -------------------------- -----------------------------------------------
 75 VSS                                (grounded)
 74 CN0/RC14/SOSCO/T1CK                SOSC0/T1CK/CN0/RC14        32kHz Oscillator, J2 pin (timer)
                                                                  J2 pin 32 (secondary OSC)
 73 CN1/RC13/SOSCI                     SOSC1/CN1/RC13             32kHz Oscillator
                                                                  J2 pin 32 (secondary OSC)
 72 OC1/INT0/RD0/SDO1                  SDO1/INT0/OC1/RD0          User LED D4 (high illuminates)
                                                                  J2 pin 87 (EXT_INT)
                                                                  J2 pin 95 (SPI1)
                                                                  J2 pin 46 (OC/PWM)
 71 PMA14/AEMDC/EMDC/IC4/PMCS1/RD11    EMDC                       Ethernet MDC
 70 PMA15/IC3/PMCS2/RD10/SCK1          SCK1/IC3/PMPCS2/RD10       J2 pin 29 (PMP control)
                                                                  J2 pin 91 (SPI1)
                                                                  J2 pin 52 (input capture)
 69 IC2/RD9/SS1                        SS1/IC2/RD9                J2 pin 54 (input capture)
 68 AEMDIO/EMDIO/IC1/RD8/RTCC          EMDIO                      Ethernet MDIO
 67 AETXEN/INT4/RA15/SDA1              ETXEN(2)                   Ethernet TX_EN
 66 AETXCLK/INT3/RA14/SCL1             INT3/SCL1/RA14             Ethernet PWR_DOWN/INT
 65 VSS                                (grounded)                 ---
 64 CLKO/OSC2/RC15                                                8MHz crystal
 63 CLKI/OSC1/RC12                                                8MHz crystal
 62 VDD                                P32_VDD                    ---
 61 RA5/TDO                            TDO/RA5                    PIC32MX440F512H debug processor
                                                                  J2 pin 118 (JTAG/GPIO)
 60 RA4/TDI                            TDI/RA4                    PIC32MX440F512H debug processor
 59 RA3/SDA2                           SDA2/RA3                   J2 pin 74 (I2C2)
 58 RA2/SCL2                           SCL2/RA2                   J2 pin 76 (I2C2)
 57 D+/RG2                             D+/RG2                     Host port (J4), Device OTG port (J5)
 56 D-/RG3                             D-/RG3                     Host port (J4), Device OTG port (J5)
 55 VUSB                               P32_VDD                    ---
 54 VBUS                               P32_VBUS                   ---
 53 RF8/SCL3/SDO3/U1TX                 SCM1B/RF8                  J2 pin 90 (UART1)
 52 RF2/SDA3/SDI3/U1RX                 SCM1A/RF2                  J2 pin 88 (UART1)
 51 RF3/USBID                          USBID/RF3                  Device OTG port (J5)

TOP SIDE, LEFT-TO-RIGHT (if pin 1 is in upper left)
--- ---------------------------------- -------------------------- -----------------------------------------------
PIN CONFIGURATIONS                     SIGNAL NAME                ON-BOARD CONNECTIONS
    (Family Data Sheet Table 1-1)     (Starter Kit User Guide)
--- ---------------------------------- -------------------------- -----------------------------------------------
100 PMD4/RE4                           PMPD4/RE4                  J2 pin 15 (PMP data)
 99 PMD3/RE3                           PMPD3/RE3                  J2 pin 17 (PMP data)
 98 PMD2/RE2                           PMPD2/RE2                  J2 pin 19 (PMP data)
 97 RG13/TRD0                          TRD0/RG13                  J2 pin 8 (Trace/GPIO)
 96 RG12/TRD1                          TRD1/RG12                  J2 pin 5
 95 RG14/TRD2                          TRD2/RG14                  J2 pin 3
 94 PMD1/RE1                           PMPD1/RE1                  J2 pin 21 (PMP data)
 93 PMD0/RE0                           PMPD0/RE0                  J2 pin 23 (PMP data)
 92 RA7/TRD3                           TRD3/RA7                   J2 pin 6 (Trace/GPIO)
 91 RA6/TRCLK                          TRCLK/RA6                  J2 pin 4 (Trace/GPIO)
 90 PMD8/C2RX/RG0                      PMPD8/RG0                  J2 pin 10 (PMP data)
 89 PMD9/C2TX/ETXERR/RG1               PMPD9/RG1                  J2 pin 14 (PMP data)
 88 PMD10/C1TX/ETXD0/RF1               PMPD10/RF1                 J2 pin 16 (PMP data)
 87 PMD11/C1RX/ETXD1/RF0               PMPD11/RF0                 J2 pin 18 (PMP data)
 86 VDD                                P32_VDD                    ---
 85 VCAP/VCORE                         (capacitor to ground)      ---
 84 PMD15/CN16/ETXCLK/RD7              PMPD15/CN16/RD7            Switch SW2 (low when closed)
                                                                  J2 pin 26 (PMP data)
 83 PMD14/CN15/ETXEN/RD6               PMPD14/CN15/RD6            Switch SW1 (low when closed)
                                                                  J2 pin 24 (PMP data)
 82 CN14/PMRD/RD5                      PMPRD/CN14/RD5             J2 pin 25
 81 CN13/OC5/PMWR/RD4                  PMPWR/OC5/C13/RD4          J2 pin 28 (PMP control)
                                                                  J2 pin 38
 80 PMD13/CN19/ETXD3/RD13              CN19/PMPD13/RD13           Switch SW3 (low when closed)
                                                                  J2 pin 22 (PMP data)
 79 PMD12/ETXD2/IC5/RD12               IC5/PMPD12/RD12            J2 pin 20 (PMP data)
                                                                  J2 pin 48
 78 OC4/RD3                            OC4/RD3                    J2 pin 40 (OC/PWM)
 77 OC3/RD2                            OC3/RD2                    User LED D5 (high illuminates)
                                                                  J2 pin 42 (OC/PWM)
 76 OC2/RD1                            OC1/RD1                    User LED D6 (high illuminates)
                                                                  J2 pin 44 (OC/PWM)

MEB Connector
=============

The following table summarizes how the pins brought the MEB through the
J2 on the Ethernet Starter Kit are mapped.  This connect is J2 on the Ethernet
Starter Kit and J3 on the MEB.

                           J3
PIC32 SIGNAL               PIN     CONNECTION
-------------------------- ------- ----------------------------------
PMPD0                      pin 23  Graphics Controller (SSD1926)
PMPD1                      pin 21  8-bit or 16-bit Data Bus
PMPD2                      pin 19
PMPD3                      pin 17
PMPD4                      pin 15
PMPD6                      pin 9
PMPD7                      pin 7
-------------------------- ------- ----------------------------------
PMPD8                      pin 10  Graphics Controller (SSD1926)
PMPD9                      pin 14  16-bit Data Bus
PMPD10                     pin 16
PMPD11                     pin 18
PMPD12                     pin 20
PMPD13                     pin 22
PMPD14                     pin 24
PMPD15                     pin 26
-------------------------- ------- ----------------------------------
                                   Graphics Controller (SSD1926)
RG13                       pin 8   Chip select
RB10                       pin 101 Register select
RC3                        pin 39  Wait line
RA10                       pin 115 Reset (see MRF24WBOMA and PICtail)
-------------------------- ------- ----------------------------------
                                   Touchscreen
RB11                       pin 103 X+
RB12                       pin 105 Y-
RB13                       pin 107 X-
RB14                       pin 127 Y+
-------------------------- ------- ----------------------------------
                                   Joystick
CN2/RB0                    pin 72  Left
CN3/RB1                    pin 70  Up
CN5/RB3                    pin 66  Down
CN6/RB4                    pin 64  Right
CN12/RB15                  pin 36  Fire
-------------------------- ------- ----------------------------------
                                   LEDs
RD1                        pin 44  LED1
RD2                        pin 42  LED2
RD3                        pin 40  LED3
RC1                        pin 35  LED4
RC2                        pin 37  LED5
-------------------------- ------- ----------------------------------
SDA2                       pin 74  I2C2 bus for BMA150, MCHP24LC08
SCL2                       pin 76  and WM8731 (see also MRF24WBOMA)
-------------------------- ------- ----------------------------------
SCK1                       pin 91  SPI1 bus for WM8731
SDI1                       pin 93
SDO1                       pin 95
-------------------------- ------- ----------------------------------
RA6                        pin 4   CPLD
RA7                        pin 6
RG12                       pin 5
RG14                       pin 3
SCK2                       pin 45  (see MRF24WBOMA)
SDI2                       pin 47  (see MRF24WBOMA)
SDO2                       pin 49  (see MRF24WBOMA)
RG9                        pin 51  (see MRF24WBOMA)
SCK3A                      pin 106 (see PICtail)
SDI3A                      pin 110 (see PICtail)
SDO3A                      pin 112 (see PICtail)
RF12                       pin 108 (see PICtail)
~SSI                       pin 97  (see PICtail)
RD9                        pin 54
-------------------------- ------- ----------------------------------
INT3                       pin 81  MRF24WBOMA
RA10                       pin 115 (also Graphics Controller and PICtail)
RB8                        pin 71
-------------------------- ------- ----------------------------------
                                   PICtail J5
SDA2                       pin 74  I2C2 bus (see above)
SCL2                       pin 76  I2C2 bus (see above)
SCK2                       pin 45  (see CPLD)
SDI2                       pin 47  (see CPLD)
SDO2                       pin 49  (see CPLD)
RG9                        pin 51  (see CPLD)
U1RX                       pin 88
U1TX                       pin 90
~U1RTS                     pin 92
~U1CTS                     pin 94
RB9                        pin 73
RA10                       pin 115 Reset (see Graphics controller and MRF24WBOMA)
INT1                       pin 85
SCL1                       pin 84
SDA1                       pin 86  (see CPLD)
~SSI                       pin 97  (see CPLD)
U2RX                       pin 110 (see CPLD)
U2TX                       pin 112 (see CPLD)
~U2RTS                     pin 106 (see CPLD)
~U2CTS                     pin 108 (see CPLD)

PICtail
=======

The MEB brings many of the signals out via the PICtail (J5).  J5 is
a 28 pin connector bringing out signals as summarized here (J3 is the
designation of the connection to the Ethernet starter kit on the
MEB side):

--- --- ------------------------
J3  J5   Table 2-1
PIN PIN  Description
--- --- ------------------------
      1  3.3V
      2  I/O_4 (Test Point)
 76   3  SCL2
 84   4  SCL1
 74   5  SDA2
 86   6  SDA1
 47   7  SDI2/SDI2A/CN9/RG7
 97   8  SS1, WFI_SDO
 49   9  SDO2/SDO2A
     10  WFI_SDI
 45  11  SCK2/SCK2A
     12  WFI_SCK
 51  13  SS2/SS2A/RG9
     14  SS1/RB2
 88  15  U1RX/SDI1A
110  16  U2RX/SDI3A
 90  17  U1TX/RA10
112  18  U2TX/SDO3A
 92  19  U1RTS/C2OUT/AN9
106  20  U2RTS/SCK3A
 94  21  U1CTS/SDO1A
108  22  U2CTS/SS3A/RF12
 73  23  RB9/INT1/RE8
 115 25  RA10/SCK1A
     26  3.3V
 85  27  INT1/SS1/RD14
     28  GND

Toolchains
==========

  MPLAB/C32
  ---------

  I am using the free, "Lite" version of the PIC32MX toolchain available
  for download from the microchip.com web site.  I am using the Windows
  version.  The MicroChip toolchain is the only toolchain currently
  supported in these configurations, but it should be a simple matter to
  adapt to other toolchains by modifying the Make.defs file include in
  each configuration.

  C32 Toolchain Options:

    CONFIG_MIPS32_TOOLCHAIN_MICROCHIPW      - MicroChip full toolchain for Windows
    CONFIG_MIPS32_TOOLCHAIN_MICROCHIPL      - MicroChip full toolchain for Linux
    CONFIG_MIPS32_TOOLCHAIN_MICROCHIPW_LITE - MicroChip "Lite" toolchain for Windows
    CONFIG_MIPS32_TOOLCHAIN_MICROCHIPL_LITE - MicroChip "Lite" toolchain for Linux
    CONFIG_MIPS32_TOOLCHAIN_PINGUINOL       - Pinquino toolchain for Linux
    CONFIG_MIPS32_TOOLCHAIN_PINGUINOW       - Pinquino toolchain for Windows
    CONFIG_MIPS32_TOOLCHAIN_MICROCHIPOPENL  - Microchip open toolchain for Linux
    CONFIG_MIPS32_TOOLCHAIN_GNU_ELF         - General mips-elf toolchain for Linux

  NOTE:  The "Lite" versions of the toolchain does not support C++.  Also
  certain optimization levels are not supported by the "Lite" toolchain.

  MicrochipOpen
  -------------

  An alternative, build-it-yourself toolchain is available here:
  http://sourceforge.net/projects/microchipopen/ .  These tools were
  last updated circa 2010.  NOTE:  C++ support still not available
  in this toolchain.

  Building MicrochipOpen (on Linux)

  1) Get the build script from this location:

      http://microchipopen.svn.sourceforge.net/viewvc/microchipopen/ccompiler4pic32/buildscripts/trunk/

  2) Build the code using the build script, for example:

      ./build.sh -b v105_freeze

     This will check out the selected branch and build the tools.

  3) Binaries will then be available in a subdirectory with a name something like
     pic32-v105-freeze-20120622/install-image/bin (depending on the current data
     and the branch that you selected.

     Note that the tools will have the prefix, mypic32- so, for example, the
     compiler will be called mypic32-gcc.

  Pinguino mips-elf Toolchain
  ---------------------------

  Another option is the mips-elf toolchain used with the Pinguino project.  This
  is a relatively current mips-elf GCC and should provide free C++ support as
  well. This toolchain can be downloded from the Pinguino website:
  http://wiki.pinguino.cc/index.php/Main_Page#Download . There is some general
  information about using the Pinguino mips-elf toolchain in this thread:
  https://groups.yahoo.com/neo/groups/nuttx/conversations/messages/1821

  See also configs/mirtoo/README.txt.  There is an experimental (untested)
  configuration for the Mirtoo platform in that directory.

  MPLAB/C32 vs MPLABX/X32
  -----------------------

  It appears that Microchip is phasing out the MPLAB/C32 toolchain and replacing
  it with MPLABX and XC32.  At present, the XC32 toolchain is *not* compatible
  with the NuttX build scripts.  Here are some of the issues that I see when trying
  to build with XC32:

  1) Make.def changes:  You have to change the tool prefix:

     CROSSDEV=xc32-

  2) debug.ld/release.ld:  The like expect some things that are not present in
     the current linker scripts (or are expected with different names).  Here
     are some partial fixes:

     Rename:  kseg0_progmem to kseg0_program_mem
     Rename:  kseg1_datamem to kseg1_data_mem

  Even then, there are more warnings from the linker and some undefined symbols
  for non-NuttX code that resides in the unused Microchip libraries.  See this
  email thread at https://groups.yahoo.com/neo/groups/nuttx/conversations/messages/1458 for more
  information.  You will have to solve at least this undefined symbol problem if
  you want to used the XC32 toolchain.

  Windows Native Toolchains
  -------------------------

  NOTE:  There are several limitations to using a Windows based toolchain in a
  Cygwin environment.  The three biggest are:

  1. The Windows toolchain cannot follow Cygwin paths.  Path conversions are
     performed automatically in the Cygwin makefiles using the 'cygpath' utility
     but you might easily find some new path problems.  If so, check out 'cygpath -w'

  2. Windows toolchains cannot follow Cygwin symbolic links.  Many symbolic links
     are used in Nuttx (e.g., include/arch).  The make system works around these
     problems for the Windows tools by copying directories instead of linking them.
     But this can also cause some confusion for you:  For example, you may edit
     a file in a "linked" directory and find that your changes had no effect.
     That is because you are building the copy of the file in the "fake" symbolic
     directory.  If you use a Windows toolchain, you should get in the habit of
     making like this:

       make clean_context all

     An alias in your .bashrc file might make that less painful.

Powering the Board
==================

  Ethernet Starter Kit:

    There are two ways to supply power to the PIC32 Ethernet Starter Kit:

      - USB bus power connected to USB debug connector J1.
      - An external application board with a regulated DC power supply that
        provides +5V can be connected to the J2 application board connector
        that is provided on the bottom side of the board.

    One green LED (D3) is provided to show that the PIC32 microcontroller
    is powered up.

  Ethernet Starter Kit with MEB:

    Power can be supplied to the Multimedia Expansion Board through the DC
    connector located on the Multimedia Expansion Board... By connecting
    9-14V power supply to the DC connector, the Multimedia Expansion Board
    and starter kit will receive the proper voltages. The user can also
    supply power via the starter kit. However, if the application uses
    multiple features of the Multimedia Expansion Board, it is recommended
    to use 9-14V power supply."

On Board Debug Support
======================

  The PIC32 Ethernet Starter Kit includes a PIC32MX440F512H USB microcontroller
  that provides debugger connectivity over USB. The PIC32MX440F512H is hard-wired
  to the PIC32 device to provide two types of protocol translation:

    - I/O pins of PIC32MX440F512H to the ICSP™ pins of the PIC32
    - I/O pins of PIC32MX440F512H to the JTAG pins of the PIC32

  The PIC32 Ethernet Starter Kit currently uses the JTAG pins of the PIC32 device for
  programming and debugging.

Creating Compatible NuttX HEX files
===================================

  Intel Hex Format Files:
  -----------------------

    When NuttX is built it will produce two files in the top-level NuttX
    directory:

    1) nuttx - This is an ELF file, and
    2) nuttx.hex - This is an Intel Hex format file.  This is controlled by
       the setting CONFIG_INTELHEX_BINARY in the .config file.

    The PICkit tool wants an Intel Hex format file to burn into FLASH. However,
    there is a problem with the generated nutt.hex: The tool expects the nuttx.hex
    file to contain physical addresses.  But the nuttx.hex file generated from the
    top-level make will have address in the KSEG0 and KSEG1 regions.

  tools/pic32mx/mkpichex:
  ----------------------

    There is a simple tool in the NuttX tools/pic32mx directory that can be
    used to solve both issues with the nuttx.hex file.  But, first, you must
    build the tool:

      cd tools/pic32mx
      make

    Now you will have an excecutable file call mkpichex (or mkpichex.exe on
    Cygwin).  This program will take the nutt.hex file as an input, it will
    convert all of the KSEG0 and KSEG1 addresses to physical address, and
    it will write the modified file, replacing the original nuttx.hex.

    To use this file, you need to do the following things:

      export PATH=???  # Add the NuttX tools/pic32mx directory to your
                       # PATH variable
      make             # Build nuttx and nuttx.hex
      mkpichex $PWD    #  Convert addresses in nuttx.hex.  $PWD is the path
                       # to the top-level build directory.  It is the only
                       # required input to mkpichex.

Serial Console: MEB
===================

 [[Warning:  This all sounds great, but the fact is that I have not yet
   gotten any serial UART output to work from the MEB.]]

  A serial console is not required to use NuttX.  However, all of the
  Nuttx example code in the apps/examples assumes that you have a
  serial console.  The Ethernet Starter Kit(even with the MEB) does not
  have any RS-232 connector needed to drive the serial console.

  Raw UART signals are available at the MEB's PICtail connector, however,
  and can be connected to an external MAX2232 board to get a serial console.
  The defconfig files are set up to use UART2.  So the proper connections
  would be:

  PICtail
  PIN      FUNCTION
  -------- -----------
      1    3.3V
     16    U2RX
     18    U2TX
     28    GND

  UART1 is also brought out on the PICtail and would be connected as:

  PICtail
  PIN      FUNCTION
  -------- -----------
      1    3.3V
     15    U1RX
     17    U1TX
     28    GND

  Here is a summary of the tortuous routes taken by the PIC32MX UART pins:

  --- ---------------------------------- -------------------------- -------------------------
  PIN CONFIGURATIONS                     SIGNAL NAME                ON-BOARD CONNECTIONS
      (Family Data Sheet Table 1-1)     (Starter Kit User Guide)
  --- ---------------------------------- -------------------------- -------------------------

   39 AC1TX/RF13/SCK4/U2RTS/U5TX         SCM3D/BCLK2/RF13           J2 pin 106 (UART2)
   40 AC1RX/RF12/SS4/U2CTS/U5RX          SCM3C/RF12                 J2 pin 108 (UART2)
   49 PMA9/CN17/RF4/SDA5/SDI4/U2RX       PMPA9/SCM3A/CN17/RF4       J2 pin 109 (PMP address)
                                                                    J2 pin 110 (UART2)
   50 PMA8/CN18/RF5/SCL5/SDO4/U2TX       PMPA8/SCM3B/CN18/RF5       J2 pin 111 (PMP address)
                                                                    J2 pin 112 (UART2)
   52 RF2/SDA3/SDI3/U1RX                 SCM1A/RF2                  J2 pin  88 (UART1)
   53 RF8/SCL3/SDO3/U1TX                 SCM1B/RF8                  J2 pin  90 (UART1)

  J2 is the connector at the bottom of the Ethernet start kit that
  mates the Ethernet Starter kit to the MEB.  The MEB then makes the
  following signals available on the PICtail (J5):

  MEB Connector:

  -------------------------- ------- ----------------------------------
  Signal                     J3
  -------------------------- -------
  U1RX                       pin 88
  U1TX                       pin 90
  ~U1RTS                     pin 92
  ~U1CTS                     pin 94
  U2RX                       pin 110
  U2TX                       pin 112
  ~U2RTS                     pin 106
  ~U2CTS                     pin 108
  -------------------------- -------

  PICtail:

  The pins are labeled differently in Table 2-1 and in the schematic.  This is
  confusing.  I will trust Table 2-1.

  --- --- ------- --- --- -----------------
      Table 2-1       Schematic
  J3  J5           J3  J5
  PIN PIN  NAME    PIN PIN Description
  --- --- ------- ---- --- ------------
                         1  3.3V
   88  15  U1RX     88  15  SDI1A
  110  16  U2RX    110  16  SDI3A
   90  17  U1TX         17  RA10
                    90      SD01A
  112  18  U2TX    113  18  SDO3A
   92  19  U1RTS        19  C2OUT/AN9
                    92      SCK1A
  106  20  U2RTS   106  20  SCK3A
   94  21  U1CTS        21  SDO1A
                    94      SS1/RD14
  108  22  U2CTS   108  22  SS3A/RF12
       26  3.3V
       28  GND

Serial Console: Starter Kit I/O Expansion Board
===============================================

  U1:
  Ethernet Starter Kit                          Expansion I/O board
  --------------------------------------------- -------------------------
  PIN Description                         J2       J1  J10/J11
  --- ---------------------------------- ------------- ------------------
  47  AETXD0/CN20/RD14/SS3/U1CTS/U4RX    Not available N/A
  48  AETXD1/CN21/RD15/SCK3/U1RTS/U4TX   Not available N/A
  52  RF2/SDA3/SDI3/U1RX                 J2 pin 88     J11 pin 41
  53  RF8/SCL3/SDO3/U1TX                 J2 pin 90     J11 pin 43

  U2:
  Ethernet Starter Kit                          Expansion I/O board
  --------------------------------------------- -------------------------
  PIN Description                         J2       J1  J10/J11
  --- ---------------------------------- ------------- ------------------
  39  AC1TX/RF13/SCK4/U2RTS/U5TX         J2 pin 106    J11 pin 42
  40  AC1RX/RF12/SS4/U2CTS/U5RX          J2 pin 108    J11 pin 44
  50  PMA8/CN18/RF5/SCL5/SDO4/U2TX       J2 pin 111    J10 pin 52
                                         J2 pin 112    J11 pin 48
  49  PMA9/CN17/RF4/SDA5/SDI4/U2RX       J2 pin 109    J10 pin 51
                                         J2 pin 110    J11 pin 46

  U3:
  Ethernet Starter Kit                          Expansion I/O board
  --------------------------------------------- -------------------------
  PIN Description                         J2       J1  J10/J11
  --- ---------------------------------- ------------- ------------------
  10  PMA5/CN8/ECOL/RG6/SCK2/U3RTS/U6TX  J2 pin 45     J10 pin 23
                                         J2 pin 117    J10 pin 55
  11  PMA4/CN9/ECRS/RG7/SDA4/SDI2/U3RX   J2 pin 47     J10 pin 24
                                         J2 pin 119    J10 pin 56
  12  PMA3/AECRSDV/AERXDV/CN10/ECRSDV/   Not available N/A
      ERXDV/RG8/SCL4/SDO2/U3TX
  14  PMA2/AEREFCLK/AERXCLK/CN11/
      EREFCLK/ERXCLK/RG9/SS2/U3CTS/      Not available N/A
      U6RX

  U4:
  Ethernet Starter Kit                          Expansion I/O board
  --------------------------------------------- -------------------------
  PIN Description                         J2       J1  J10/J11
  --- ---------------------------------- ------------- ------------------
  47  AETXD0/CN20/RD14/SS3/U1CTS/U4RX    Not available N/A
  48  AETXD1/CN21/RD15/SCK3/U1RTS/U4TX   Not available N/A

  U5:
  Ethernet Starter Kit                          Expansion I/O board
  --------------------------------------------- -------------------------
  PIN Description                         J2       J1  J10/J11
  --- ---------------------------------- ------------- ------------------
  39  AC1TX/RF13/SCK4/U2RTS/U5TX         J2 pin 106    J11 pin 42
  40  AC1RX/RF12/SS4/U2CTS/U5RX          J2 pin 108    J11 pin 44

  U6:
  PIN Description
  --- ----------------------------------
  10  PMA5/CN8/ECOL/RG6/SCK2/U3RTS/U6TX  J2 pin 45     J10 pin 23
                                         J2 pin 117    J10 pin 55
  14  PMA2/AEREFCLK/AERXCLK/CN11/        Not available N/A
      EREFCLK/ERXCLK/RG9/SS2/U3CTS/
      U6RX

LEDs
====

  The PIC32MX Ethernet Starter kit has 3 user LEDs labeled LED1-3 on the
  board graphics (but referred to as LED4-6 in the schematic):

  PIN  User's Guide   Board Stencil   Notes
  ---  -------------  --------------  -------------------------
  RD0  "User LED D4"  "LED1 (RD0")    High illuminates (RED)
  RD2  "User LED D5"  "LED3 (RD2)"    High illuminates (YELLOW)
  RD1  "User LED D6"  "LED2 (RD1)"    High illuminates (GREEN)

  We will use the labels on the board to identify LEDs.  If CONFIG_ARCH_LEDS
  is defined, then NuttX will control these LEDs as follows:

                            ON                  OFF
  ------------------------- ---- ---- ---- ---- ---- ----
                            LED1 LED2 LED3 LED1 LED2 LED3
  ------------------------- ---- ---- ---- ---- ---- ----
  LED_STARTED            0  OFF  OFF  OFF  ---  ---  ---
  LED_HEAPALLOCATE       1  ON   OFF  N/C  ---  ---  ---
  LED_IRQSENABLED        2  OFF  ON   N/C  ---  ---  ---
  LED_STACKCREATED       3  ON   ON   N/C  ---  ---  ---
  LED_INIRQ              4  N/C  N/C  ON   N/C  N/C  OFF
  LED_SIGNAL             4  N/C  N/C  ON   N/C  N/C  OFF
  LED_ASSERTION          4  N/C  N/C  ON   N/C  N/C  OFF
  LED_PANIC              5  ON   N/C  N/C  OFF  N/C  N/C

  There are 5 additional LEDs available on the MEB.  These are not
  used by NuttX.

    RD1          LED1
    RD2          LED2
    RD3          LED3
    RC1          LED4
    RC2          LED5

PIC32MX Configuration Options
=============================

  General Architecture Settings:

    CONFIG_ARCH - Identifies the arch/ subdirectory.  This should
     be set to:

       CONFIG_ARCH=mips

    CONFIG_ARCH_family - For use in C code:

       CONFIG_ARCH_MIPS=y

    CONFIG_ARCH_architecture - For use in C code:

       CONFIG_ARCH_MIPS32=y

    CONFIG_ARCH_CHIP - Identifies the arch/*/chip subdirectory

       CONFIG_ARCH_CHIP=pic32mx

    CONFIG_ARCH_CHIP_name - For use in C code to identify the exact
       chip:

       CONFIG_ARCH_CHIP_PIC32MX795F512L=y

    CONFIG_ARCH_BOARD - Identifies the configs subdirectory and
       hence, the board that supports the particular chip or SoC.

       CONFIG_ARCH_BOARD=pic32mx-starterkit

    CONFIG_ARCH_BOARD_name - For use in C code

       CONFIG_ARCH_BOARD_PIC32MX_STARTERKIT=y

    CONFIG_ARCH_LOOPSPERMSEC - Must be calibrated for correct operation
       of delay loops

    CONFIG_ENDIAN_BIG - define if big endian (default is little
       endian)

    CONFIG_RAM_SIZE - Describes the installed DRAM (CPU SRAM in this case):

       CONFIG_RAM_SIZE=(32*1024) (32Kb)

       There is an additional 32Kb of SRAM in AHB SRAM banks 0 and 1.

    CONFIG_RAM_START - The start address of installed DRAM

       CONFIG_RAM_START=0xa0000000

    CONFIG_ARCH_LEDS - Use LEDs to show state. Unique to boards that
       have LEDs

    CONFIG_ARCH_INTERRUPTSTACK - This architecture supports an interrupt
       stack. If defined, this symbol is the size of the interrupt
       stack in bytes.  If not defined, the user task stacks will be
       used during interrupt handling.

    CONFIG_ARCH_STACKDUMP - Do stack dumps after assertions

    CONFIG_ARCH_LEDS -  Use LEDs to show state. Unique to board architecture.

    CONFIG_ARCH_CALIBRATION - Enables some build in instrumentation that
       cause a 100 second delay during boot-up.  This 100 second delay
       serves no purpose other than it allows you to calibratre
       CONFIG_ARCH_LOOPSPERMSEC.  You simply use a stop watch to measure
       the 100 second delay then adjust CONFIG_ARCH_LOOPSPERMSEC until
       the delay actually is 100 seconds.

    PIC32MX Configuration

      CONFIG_PIC32MX_MVEC - Select muli- vs. single-vectored interrupts

    Individual subsystems can be enabled:

       CONFIG_PIC32MX_WDT            - Watchdog timer
       CONFIG_PIC32MX_T2             - Timer 2 (Timer 1 is the system time and always enabled)
       CONFIG_PIC32MX_T3             - Timer 3
       CONFIG_PIC32MX_T4             - Timer 4
       CONFIG_PIC32MX_T5             - Timer 5
       CONFIG_PIC32MX_IC1            - Input Capture 1
       CONFIG_PIC32MX_IC2            - Input Capture 2
       CONFIG_PIC32MX_IC3            - Input Capture 3
       CONFIG_PIC32MX_IC4            - Input Capture 4
       CONFIG_PIC32MX_IC5            - Input Capture 5
       CONFIG_PIC32MX_OC1            - Output Compare 1
       CONFIG_PIC32MX_OC2            - Output Compare 2
       CONFIG_PIC32MX_OC3            - Output Compare 3
       CONFIG_PIC32MX_OC4            - Output Compare 4
       CONFIG_PIC32MX_OC5            - Output Compare 5
       CONFIG_PIC32MX_I2C1           - I2C 1
       CONFIG_PIC32MX_I2C2           - I2C 2
       CONFIG_PIC32MX_I2C3           - I2C 3
       CONFIG_PIC32MX_I2C4           - I2C 4
       CONFIG_PIC32MX_I2C5           - I2C 5
       CONFIG_PIC32MX_SPI1           - SPI 1
       CONFIG_PIC32MX_SPI2           - SPI 2
       CONFIG_PIC32MX_SPI3           - SPI 3
       CONFIG_PIC32MX_SPI4           - SPI 4
       CONFIG_PIC32MX_UART1          - UART 1
       CONFIG_PIC32MX_UART2          - UART 2
       CONFIG_PIC32MX_UART3          - UART 3
       CONFIG_PIC32MX_UART4          - UART 4
       CONFIG_PIC32MX_UART5          - UART 5
       CONFIG_PIC32MX_UART6          - UART 6
       CONFIG_PIC32MX_ADC            - ADC 1
       CONFIG_PIC32MX_PMP            - Parallel Master Port
       CONFIG_PIC32MX_CM1            - Comparator 1
       CONFIG_PIC32MX_CM2            - Comparator 2
       CONFIG_PIC32MX_RTCC           - Real-Time Clock and Calendar
       CONFIG_PIC32MX_DMA            - DMA
       CONFIG_PIC32MX_FLASH          - FLASH
       CONFIG_PIC32MX_USBDEV         - USB device
       CONFIG_PIC32MX_USBHOST        - USB host
       CONFIG_PIC32MX_CAN1           - Controller area network 1
       CONFIG_PIC32MX_CAN2           - Controller area network 2
       CONFIG_PIC32MX_ETHERNET       - Ethernet

    PIC32MX Configuration Settings
    DEVCFG0:
      CONFIG_PIC32MX_DEBUGGER - Background Debugger Enable. Default 3 (disabled). The
        value 2 enables.
      CONFIG_PIC32MX_ICESEL - In-Circuit Emulator/Debugger Communication Channel Select
        Default 1 (PG2)
      CONFIG_PIC32MX_PROGFLASHWP  - Program FLASH write protect.  Default 0xff (disabled)
      CONFIG_PIC32MX_BOOTFLASHWP - Default 1 (disabled)
      CONFIG_PIC32MX_CODEWP - Default 1 (disabled)
    DEVCFG1: (All settings determined by selections in board.h)
    DEVCFG2: (All settings determined by selections in board.h)
    DEVCFG3:
      CONFIG_PIC32MX_USBIDO - USB USBID Selection.  Default 1 if USB enabled
        (USBID pin is controlled by the USB module), but 0 (GPIO) otherwise.
      CONFIG_PIC32MX_VBUSIO - USB VBUSON Selection (Default 1 if USB enabled
        (VBUSON pin is controlled by the USB module, but 0 (GPIO) otherwise.
      CONFIG_PIC32MX_WDENABLE - Enabled watchdog on power up.  Default 0 (watchdog
        can be enabled later by software).

    The priority of interrupts may be specified.  The value ranage of
    priority is 4-31. The default (16) will be used if these any of these
    are undefined.

       CONFIG_PIC32MX_CTPRIO         - Core Timer Interrupt
       CONFIG_PIC32MX_CS0PRIO        - Core Software Interrupt 0
       CONFIG_PIC32MX_CS1PRIO        - Core Software Interrupt 1
       CONFIG_PIC32MX_INT0PRIO       - External Interrupt 0
       CONFIG_PIC32MX_INT1PRIO       - External Interrupt 1
       CONFIG_PIC32MX_INT2PRIO       - External Interrupt 2
       CONFIG_PIC32MX_INT3PRIO       - External Interrupt 3
       CONFIG_PIC32MX_INT4PRIO       - External Interrupt 4
       CONFIG_PIC32MX_FSCMPRIO       - Fail-Safe Clock Monitor
       CONFIG_PIC32MX_T1PRIO         - Timer 1 (System timer) priority
       CONFIG_PIC32MX_T2PRIO         - Timer 2 priority
       CONFIG_PIC32MX_T3PRIO         - Timer 3 priority
       CONFIG_PIC32MX_T4PRIO         - Timer 4 priority
       CONFIG_PIC32MX_T5PRIO         - Timer 5 priority
       CONFIG_PIC32MX_IC1PRIO        - Input Capture 1
       CONFIG_PIC32MX_IC2PRIO        - Input Capture 2
       CONFIG_PIC32MX_IC3PRIO        - Input Capture 3
       CONFIG_PIC32MX_IC4PRIO        - Input Capture 4
       CONFIG_PIC32MX_IC5PRIO        - Input Capture 5
       CONFIG_PIC32MX_OC1PRIO        - Output Compare 1
       CONFIG_PIC32MX_OC2PRIO        - Output Compare 2
       CONFIG_PIC32MX_OC3PRIO        - Output Compare 3
       CONFIG_PIC32MX_OC4PRIO        - Output Compare 4
       CONFIG_PIC32MX_OC5PRIO        - Output Compare 5
       CONFIG_PIC32MX_I2C1PRIO       - I2C 1
       CONFIG_PIC32MX_I2C2PRIO       - I2C 2
       CONFIG_PIC32MX_I2C3PRIO       - I2C 3
       CONFIG_PIC32MX_I2C4PRIO       - I2C 4
       CONFIG_PIC32MX_I2C5PRIO       - I2C 5
       CONFIG_PIC32MX_SPI2PRIO       - SPI 2
       CONFIG_PIC32MX_UART1PRIO      - UART 1
       CONFIG_PIC32MX_UART2PRIO      - UART 2
       CONFIG_PIC32MX_CN             - Input Change Interrupt
       CONFIG_PIC32MX_ADCPRIO        - ADC1 Convert Done
       CONFIG_PIC32MX_PMPPRIO        - Parallel Master Port
       CONFIG_PIC32MX_CM1PRIO        - Comparator 1
       CONFIG_PIC32MX_CM2PRIO        - Comparator 2
       CONFIG_PIC32MX_FSCMPRIO       - Fail-Safe Clock Monitor
       CONFIG_PIC32MX_RTCCPRIO       - Real-Time Clock and Calendar
       CONFIG_PIC32MX_DMA0PRIO       - DMA Channel 0
       CONFIG_PIC32MX_DMA1PRIO       - DMA Channel 1
       CONFIG_PIC32MX_DMA2PRIO       - DMA Channel 2
       CONFIG_PIC32MX_DMA3PRIO       - DMA Channel 3
       CONFIG_PIC32MX_DMA4PRIO       - DMA Channel 4
       CONFIG_PIC32MX_DMA5PRIO       - DMA Channel 5
       CONFIG_PIC32MX_DMA6PRIO       - DMA Channel 6
       CONFIG_PIC32MX_DMA7PRIO       - DMA Channel 7
       CONFIG_PIC32MX_FCEPRIO        - Flash Control Event
       CONFIG_PIC32MX_USBPRIO        - USB

  PIC32MXx specific device driver settings.  NOTE:  For the Ethernet
  starter kit, there is no RS-232 connector (even with the MEB).  See
  discussion above ("") for information about how you can configure
  an external MAX2232 board to get a serial console.

    CONFIG_UARTn_SERIAL_CONSOLE - selects the UARTn for the
       console and ttys0 (default is the UART0).
    CONFIG_UARTn_RXBUFSIZE - Characters are buffered as received.
       This specific the size of the receive buffer
    CONFIG_UARTn_TXBUFSIZE - Characters are buffered before
       being sent.  This specific the size of the transmit buffer
    CONFIG_UARTn_BAUD - The configure BAUD of the UART.  Must be
    CONFIG_UARTn_BITS - The number of bits.  Must be either 7 or 8.
    CONFIG_UARTn_PARTIY - 0=no parity, 1=odd parity, 2=even parity
    CONFIG_UARTn_2STOP - Two stop bits

PIC32MX specific PHY/Ethernet device driver settings

    CONFIG_ETH0_PHY_KS8721 - Selects the Micrel KS8721 PHY
    CONFIG_ETH0_PHY_DP83848C - Selects the National Semiconductor DP83848C PHY
    CONFIG_ETH0_PHY_LAN8720 - Selects the SMSC LAN8720 PHY
    CONFIG_PHY_AUTONEG - Enable auto-negotion
    CONFIG_PHY_SPEED100 - Select 100Mbit vs. 10Mbit speed.
    CONFIG_PHY_FDUPLEX - Select full (vs. half) duplex
    CONFIG_NET_NTXDESC - Configured number of Tx descriptors. Default: 2
    CONFIG_NET_NRXDESC - Configured number of Rx descriptors. Default: 4
    CONFIG_NET_WOL - Enable Wake-up on Lan (not fully implemented).
    CONFIG_NET_DUMPPACKET - Dump all received and transmitted packets.
      Also needs CONFIG_DEBUG_FEATURES.
    CONFIG_NET_REGDEBUG - Enabled low level register debug.  Also needs
      CONFIG_DEBUG_FEATURES.
    CONFIG_NET_HASH - Enable receipt of near-perfect match frames.
    CONFIG_PIC32MX_MULTICAST - Enable receipt of multicast (and unicast) frames.
      Automatically set if CONFIG_NET_IGMP is selected.

  Related DEVCFG3 Configuration Settings:
    CONFIG_PIC32MX_FETHIO: Ethernet I/O Pin Selection bit:
      1 = Default Ethernet I/O Pins
      0 = Alternate Ethernet I/O Pins
    CONFIG_PIC32MX_FMIIEN: Ethernet MII Enable bit
      1 = MII enabled
      0 = RMII enabled

  PIC32MXx USB Device Configuration

  PIC32MXx USB Host Configuration (the PIC32MX does not support USB Host)

Configurations
==============

Each PIC32MX configuration is maintained in a sub-directory and can be
selected as follow:

    cd tools
    ./configure.sh pic32mx-starterkit/<subdir>
    cd -

Where <subdir> is one of the following:

  nsh:

    This is the NuttShell (NSH) using the NSH startup logic at
    apps/examples/nsh.

    NOTES:

    1. This configuration uses the mconf-based configuration tool.  To
       change this configurations using that tool, you should:

       a. Build and install the kconfig-mconf tool.  See nuttx/README.txt
          see additional README.txt files in the NuttX tools repository.

       b. Execute 'make menuconfig' in nuttx/ in order to start the
          reconfiguration process.

    2. Serial Output

       The OS test produces all of its test output on the serial console.
       This configuration has UART1 enabled as a serial console.  I have
       been unable to get this UART work on the MEB.  But on the Expansion
       I/O board, this maps to RX = J11 pin 41 and TX = J11 pin 43

    3. SB Configurations

       Several USB device configurations can be enabled and included
       as NSH built-in built in functions.

       To use USB device, connect the starter kit to the host using a cable
       with a Type-B micro-plug to the starter kit’s micro-A/B port J5, located
       on the bottom side of the starter kit. The other end of the cable
       must have a Type-A plug. Connect it to a USB host. Jumper JP2 should be
       removed.

       All USB device configurations require the following basic setup in
       your NuttX configuration file to enable USB device support:

         CONFIG_USBDEV=y         : Enable basic USB device support
         CONFIG_PIC32MX_USBDEV=y : Enable PIC32 USB device support

       system/cdcacm -  The system/cdcacm program can be included by
       adding the following to the configuration file:

         CONFIG_CDCACM=y         : Enable the CDCACM device
         CONFIG_EXAMPLES_CDCACM=y

    3. Networking Configurations

       Several Networking configurations can be enabled and included
       as NSH built-in built in functions.  The following additional
       configuration settings are required:

         CONFIG_NET=y              : Enable networking support
         CONFIG_PIC32MX_ETHERNET=y : Enable the PIC32 Ethernet driver
         CONFIG_NSH_TELNET=y       : Enable the Telnet NSH console (optional)

       NOTES:

       a. This logic will assume that a network is connected.  During its
          initialization, it will try to negotiate the link speed.  If you have
          no network connected when you reset the board, there will be a long
          delay (maybe 30 seconds?) before anything happens.  That is the timeout
          before the networking finally gives up and decides that no network is
          available.

       b. This example can support an FTP client.  In order to build in FTP client
          support simply add the following to the Nuttx configuration file:

         CONFIG_NETUTILS_FTPC=y
         CONFIG_EXAMPLES_FTPC=y

       c. This example can support an FTP server.  In order to build in FTP server
          support simply add the following to the Nuttx configuration file:

         CONFIG_DISABLE_POLL=n
         CONFIG_NETUTILS_FTPD=y
         CONFIG_EXAMPLES_FTPD=y

  nsh2:

    This is an alternative NSH configuration.  Without the Expansion I/O board,
    there is no way to connect a serial console.  This NSH alternative supports
    only a Telnet console.  The nsh2 differs from the nsh configuration in the
    following ways:

    NOTES:

    1. Networking is enabled:

       CONFIG_NET=y                : Enable networking support
       CONFIG_PIC32MX_ETHERNET=y   : Enable the PIC32 Ethernet driver
       CONFIG_NSH_CONSOLE=n        : Disable NSH serial console
       CONFIG_NSH_TELNET=y         : Enable the Telnet NSH console

       See apps/nshlib/README.txt for other NSH networking-related configuration
       settings.

    2. UART1 is disabled

      CONFIG_PIC32MX_UART1=n        : UART1 is disabled (as well as other UARTs)
      CONFIG_UART1_SERIAL_CONSOLE=n : There is no serial console

    3. The RAM log is enabled"

      CONFIG_RAMLOG=y             : Enable the RAM-based logging feature.
      CONFIG_RAMLOG_CONSOLE=n     : (there is no default console device)
      CONFIG_RAMLOG_SYSLOG=y      : This enables the RAM-based logger as the
                                    system logger.

      Logging is currently set up to use 16Kb of memory:

      CONFIG_RAMLOG_BUFSIZE=16384

    There are a few other configuration differences as necessary to support
    this different device configuration. Just the do the 'diff' if you are
    curious.

    NOTES:
      See the notes for the nsh configuration.  Most also apply to the nsh2
      configuration.

  Using a RAM disk and the USB MSC device with nsh and nsh2
  ---------------------------------------------------------
  Here is an experimental change to either examples/nsh or examples/nsh2
  that will create a RAM disk and attempt to export that RAM disk as a
  USB mass storage device.

  1. Changes to nuttx/.config

    a) Enable support for the PIC32 USB device

      -CONFIG_PIC32MX_USBDEV=n
      +CONFIG_PIC32MX_USBDEV=y

    b) Enable NuttX USB device support

      -CONFIG_USBDEV=n
      +CONFIG_USBDEV=y

    c) Enable the USB MSC class driver

      -CONFIG_USBMSC=n
      +CONFIG_USBMSC=y

    d) Use a RAM disk (instead of an SD card) as the USB MSC logical unit:

      -CONFIG_SYSTEM_USBMSC_DEVPATH1="/dev/mmcsd0"
      +CONFIG_SYSTEM_USBMSC_DEVPATH1="/dev/ram0"

    e) Enable building of the system/usbmsc:

      +CONFIG_SYSTEM_USBMSC=y

  3. When NSH first comes up, you must manually create the RAM disk
     before exporting it:

    a) Create a 64Kb RAM disk at /dev/ram0:

      nsh> mkrd -s 512 128

    b) Put a FAT file system on the RAM disk:

      nsh> mkfatfs /dev/ram0

    b) Now the 'msconn' command will connect to the host and
       export /dev/ram0 as the USB logical unit:

      nsh> msconn

    NOTE:  This modification should be considered experimental.  IN the
    little testing I have done with it, it appears functional.  But the
    logic has not been stressed and there could still be lurking issues.
    (There is a bug associated with this configuration listed in the
    top-level TODO list).
