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README ^^^^^^ README for NuttX port to the Olimex LPC1766-STK development board Contents ^^^^^^^^ Olimex LPC1766-STK development board Development Environment GNU Toolchain Options IDEs NuttX buildroot Toolchain LEDs Using OpenOCD and GDB with an FT2232 JTAG emulator Olimex LPC1766-STK Configuration Options Configurations Olimex LPC1766-STK development board ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ GPIO Usage: ----------- GPIO PIN SIGNAL NAME -------------------------------- ---- -------------- P0[0]/RD1/TXD3/SDA1 46 RD1 P0[1]/TD1/RXD3/SCL1 47 TD1 P0[2]/TXD0/AD0[7] 98 TXD0 P0[3]/RXD0/AD0[6] 99 RXD0 P0[4]/I2SRX_CLK/RD2/CAP2[0] 81 LED2/ACC IRQ P0[5]/I2SRX_WS/TD2/CAP2[1] 80 CENTER P0[6]/I2SRX_SDA/SSEL1/MAT2[0] 79 SSEL1 P0[7]/I2STX_CLK/SCK1/MAT2[1] 78 SCK1 P0[8]/I2STX_WS/MISO1/MAT2[2] 77 MISO1 P0[9]/I2STX_SDA/MOSI1/MAT2[3] 76 MOSI1 P0[10]/TXD2/SDA2/MAT3[0] 48 SDA2 P0[11]/RXD2/SCL2/MAT3[1] 49 SCL2 P0[15]/TXD1/SCK0/SCK 62 TXD1 P0[16]/RXD1/SSEL0/SSEL 63 RXD1 P0[17]/CTS1/MISO0/MISO 61 CTS1 P0[18]/DCD1/MOSI0/MOSI 60 DCD1 P0[19]/DSR1/SDA1 59 DSR1 P0[20]/DTR1/SCL1 58 DTR1 P0[21]/RI1/RD1 57 MMC PWR P0[22]/RTS1/TD1 56 RTS1 P0[23]/AD0[0]/I2SRX_CLK/CAP3[0] 9 BUT1 P0[24]/AD0[1]/I2SRX_WS/CAP3[1] 8 TEMP P0[25]/AD0[2]/I2SRX_SDA/TXD3 7 MIC IN P0[26]/AD0[3]/AOUT/RXD3 6 AOUT P0[27]/SDA0/USB_SDA 25 USB_SDA P0[28]/SCL0/USB_SCL 24 USB_SCL P0[29]/USB_D+ 29 USB_D+ P0[30]/USB_D- 30 USB_D- P1[0]/ENET_TXD0 95 E_TXD0 P1[1]/ENET_TXD1 94 E_TXD1 P1[4]/ENET_TX_EN 93 E_TX_EN P1[8]/ENET_CRS 92 E_CRS P1[9]/ENET_RXD0 91 E_RXD0 P1[10]/ENET_RXD1 90 E_RXD1 P1[14]/ENET_RX_ER 89 E_RX_ER P1[15]/ENET_REF_CLK 88 E_REF_CLK P1[16]/ENET_MDC 87 E_MDC P1[17]/ENET_MDIO 86 E_MDIO P1[18]/USB_UP_LED/PWM1[1]/CAP1[0] 32 USB_UP_LED P1[19]/MC0A/#USB_PPWR/CAP1[1] 33 #USB_PPWR P1[20]/MCFB0/PWM1[2]/SCK0 34 SCK0 P1[21]/MCABORT/PWM1[3]/SSEL0 35 SSEL0 P1[22]/MC0B/USB_PWRD/MAT1[0] 36 USBH_PWRD P1[23]/MCFB1/PWM1[4]/MISO0 37 MISO0 P1[24]/MCFB2/PWM1[5]/MOSI0 38 MOSI0 P1[25]/MC1A/MAT1[1] 39 LED1 P1[26]/MC1B/PWM1[6]/CAP0[0] 40 CS_UEXT P1[27]/CLKOUT/#USB_OVRCR/CAP0[1] 43 #USB_OVRCR P1[28]/MC2A/PCAP1[0]/MAT0[0] 44 P1.28 P1[29]/MC2B/PCAP1[1]/MAT0[1] 45 P1.29 P1[30]/VBUS/AD0[4] 21 VBUS P1[31]/SCK1/AD0[5] 20 AIN5 P2[0]/PWM1[1]/TXD1 75 UP P2[1]/PWM1[2]/RXD1 74 DOWN P2[2]/PWM1[3]/CTS1/TRACEDATA[3] 73 TRACE_D3 P2[3]/PWM1[4]/DCD1/TRACEDATA[2] 70 TRACE_D2 P2[4]/PWM1[5]/DSR1/TRACEDATA[1] 69 TRACE_D1 P2[5]/PWM1[6]/DTR1/TRACEDATA[0] 68 TRACE_D0 P2[6]/PCAP1[0]/RI1/TRACECLK 67 TRACE_CLK P2[7]/RD2/RTS1 66 LEFT P2[8]/TD2/TXD2 65 RIGHT P2[9]/USB_CONNECT/RXD2 64 USBD_CONNECT P2[10]/#EINT0/NMI 53 ISP_E4 P2[11]/#EINT1/I2STX_CLK 52 #EINT1 P2[12]/#EINT2/I2STX_WS 51 WAKE-UP P2[13]/#EINT3/I2STX_SDA 50 BUT2 P3[25]/MAT0[0]/PWM1[2] 27 LCD_RST P3[26]/STCLK/MAT0[1]/PWM1[3] 26 LCD_BL Serial Console -------------- The LPC1766-STK board has two serial connectors. One, RS232_0, connects to the LPC1766 UART0. This is the DB-9 connector next to the power connector. The other RS232_1, connect to the LPC1766 UART1. This is he DB-9 connector next to the Ethernet connector. Simple UART1 is the more flexible UART and since the needs for a serial console are minimal, the more minimal UART0/RS232_0 is used for the NuttX system console. Of course, this can be changed by editting the NuttX configuration file as discussed below. The serial console is configured as follows (57600 8N1): BAUD: 57600 Number of Bits: 8 Parity: None Stop bits: 1 You will need to connect a monitor program (Hyperterminal, Tera Term, minicom, whatever) to UART0/RS232_0 and configure the serial port as shown above. NOTE: The ostest example works fine at 115200, but the other configurations have problems at that rate (probably because they use the interrupt driven serial driver). Other LPC17xx boards with the same clocking will run at 115200. Development Environment ^^^^^^^^^^^^^^^^^^^^^^^ Either Linux or Cygwin on Windows can be used for the development environment. The source has been built only using the GNU toolchain (see below). Other toolchains will likely cause problems. Testing was performed using the Cygwin environment. GNU Toolchain Options ^^^^^^^^^^^^^^^^^^^^^ The NuttX make system has been modified to support the following different toolchain options. 1. The CodeSourcery GNU toolchain, 2. The devkitARM GNU toolchain, 3. The NuttX buildroot Toolchain (see below). All testing has been conducted using the NuttX buildroot toolchain. However, the make system is setup to default to use the devkitARM toolchain. To use the CodeSourcery or devkitARM toolchain, you simply need add one of the following configuration options to your .config (or defconfig) file: CONFIG_LPC17_CODESOURCERYW=y : CodeSourcery under Windows CONFIG_LPC17_CODESOURCERYL=y : CodeSourcery under Linux CONFIG_LPC17_DEVKITARM=y : devkitARM under Windows CONFIG_LPC17_BUILDROOT=y : NuttX buildroot under Linux or Cygwin (default) If you are not using CONFIG_LPC17_BUILDROOT, then you may also have to modify the PATH in the setenv.h file if your make cannot find the tools. NOTE: the CodeSourcery (for Windows)and devkitARM are Windows native toolchains. The CodeSourcey (for Linux) and NuttX buildroot toolchains are Cygwin and/or Linux native toolchains. 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 not 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. 3. Dependencies are not made when using Windows versions of the GCC. This is because the dependencies are generated using Windows pathes which do not work with the Cygwin make. Support has been added for making dependencies with the windows-native toolchains. That support can be enabled by modifying your Make.defs file as follows: - MKDEP = $(TOPDIR)/tools/mknulldeps.sh + MKDEP = $(TOPDIR)/tools/mkdeps.sh --winpaths "$(TOPDIR)" If you have problems with the dependency build (for example, if you are not building on C:), then you may need to modify tools/mkdeps.sh NOTE 1: The CodeSourcery toolchain (2009q1) does not work with default optimization level of -Os (See Make.defs). It will work with -O0, -O1, or -O2, but not with -Os. NOTE 2: The devkitARM toolchain includes a version of MSYS make. Make sure that the paths to Cygwin's /bin and /usr/bin directories appear BEFORE the devkitARM path or will get the wrong version of make. IDEs ^^^^ NuttX is built using command-line make. It can be used with an IDE, but some effort will be required to create the project (There is a simple RIDE project in the RIDE subdirectory). Makefile Build -------------- Under Eclipse, it is pretty easy to set up an "empty makefile project" and simply use the NuttX makefile to build the system. That is almost for free under Linux. Under Windows, you will need to set up the "Cygwin GCC" empty makefile project in order to work with Windows (Google for "Eclipse Cygwin" - there is a lot of help on the internet). Native Build ------------ Here are a few tips before you start that effort: 1) Select the toolchain that you will be using in your .config file 2) Start the NuttX build at least one time from the Cygwin command line before trying to create your project. This is necessary to create certain auto-generated files and directories that will be needed. 3) Set up include pathes: You will need include/, arch/arm/src/lpc17xx, arch/arm/src/common, arch/arm/src/cortexm3, and sched/. 4) All assembly files need to have the definition option -D __ASSEMBLY__ on the command line. Startup files will probably cause you some headaches. The NuttX startup file is arch/arm/src/lpc17x/lpc17_vectors.S. NuttX buildroot Toolchain ^^^^^^^^^^^^^^^^^^^^^^^^^ A GNU GCC-based toolchain is assumed. The files */setenv.sh should be modified to point to the correct path to the Cortex-M3 GCC toolchain (if different from the default in your PATH variable). If you have no Cortex-M3 toolchain, one can be downloaded from the NuttX SourceForge download site (https://sourceforge.net/project/showfiles.php?group_id=189573). This GNU toolchain builds and executes in the Linux or Cygwin environment. 1. You must have already configured Nuttx in <some-dir>/nuttx. cd tools ./configure.sh olimex-lpc1766stk/<sub-dir> 2. Download the latest buildroot package into <some-dir> 3. unpack the buildroot tarball. The resulting directory may have versioning information on it like buildroot-x.y.z. If so, rename <some-dir>/buildroot-x.y.z to <some-dir>/buildroot. 4. cd <some-dir>/buildroot 5. cp configs/cortexm3-defconfig-4.3.3 .config 6. make oldconfig 7. make 8. Edit setenv.h, if necessary, so that the PATH variable includes the path to the newly built binaries. See the file configs/README.txt in the buildroot source tree. That has more detailed PLUS some special instructions that you will need to follow if you are building a Cortex-M3 toolchain for Cygwin under Windows. NOTE: This is an OABI toolchain. LEDs ^^^^ If CONFIG_ARCH_LEDS is defined, then support for the LPC1766-STK LEDs will be included in the build. See: - configs/olimex-lpc1766stk/include/board.h - Defines LED constants, types and prototypes the LED interface functions. - configs/olimex-lpc1766stk/src/lpc1766stk_internal.h - GPIO settings for the LEDs. - configs/olimex-lpc1766stk/src/up_leds.c - LED control logic. The LPC1766-STK has two LEDs. If CONFIG_ARCH_LEDS is defined, these LEDs will be controlled as follows for NuttX debug functionality (where NC means "No Change"). Basically, LED1: - OFF means that the OS is still initializing. Initialization is very fast so if you see this at all, it probably means that the system is hanging up somewhere in the initialization phases. - ON means that the OS completed initialization. LED2: - ON/OFF toggles means that various events are happening. - GLowing: LED2 is turned on and off on every interrupt so even timer interrupts should cause LED2 to glow faintly in the normal case. - Flashing. If the LED2 is flashing at about 0.5Hz, that means that a crash has occurred. If CONFIG_ARCH_STACKDUMP=y, you will get some diagnostic information on the console to help debug what happened. NOTE: LED2 is controlled by a jumper labeled: ACC_IRQ/LED2. That jump must be in the LED2 position in order to support LED2. LED1 LED2 Meaning ----- -------- -------------------------------------------------------------------- OFF OFF Still initializing and there is no interrupt activity. Initialization is very fast so if you see this, it probably means that the system is hung up somewhere in the initialization phases. OFF Glowing Still initializing (see above) but taking interrupts. OFF ON This would mean that (1) initialization did not complete but the software is hung, perhaps in an infinite loop, somewhere inside of an interrupt handler. OFF Flashing Ooops! We crashed before finishing initialization. ON OFF The system has completed initialization, but is apparently not taking any interrupts. ON Glowing This is the normal healthy state: The OS successfully initialized and is taking interrupts. ON ON This would mean that (1) the OS complete initialization, but (2) the software is hung, perhaps in an infinite loop, somewhere inside of a signal or interrupt handler. ON Flashing Ooops! We crashed sometime after initialization. Using OpenOCD and GDB with an FT2232 JTAG emulator ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Downloading OpenOCD You can get information about OpenOCD here: http://openocd.berlios.de/web/ and you can download it from here. http://sourceforge.net/projects/openocd/files/. To get the latest OpenOCD with more mature lpc17xx, you have to download from the GIT archive. git clone git://openocd.git.sourceforge.net/gitroot/openocd/openocd At present, there is only the older, frozen 0.4.0 version. These, of course, may have changed since I wrote this. Building OpenOCD under Cygwin: You can build OpenOCD for Windows using the Cygwin tools. Below are a few notes that worked as of November 7, 2010. Things may have changed by the time you read this, but perhaps the following will be helpful to you: 1. Install Cygwin (http://www.cygwin.com/). My recommendation is to install everything. There are many tools you will need and it is best just to waste a little disk space and have everthing you need. Everything will require a couple of gigbytes of disk space. 2. Create a directory /home/OpenOCD. 3. Get the FT2232 drivr from http://www.ftdichip.com/Drivers/D2XX.htm and extract it into /home/OpenOCD/ftd2xx $ pwd /home/OpenOCD $ ls CDM20802 WHQL Certified.zip $ mkdir ftd2xx $ cd ftd2xx $ unzip ..CDM20802\ WHQL\ Certified.zip Archive: CDM20802 WHQL Certified.zip ... 3. Get the latest OpenOCD source $ pwd /home/OpenOCD $ git clone git://openocd.git.sourceforge.net/gitroot/openocd/openocd You will then have the source code in /home/OpenOCD/openocd 4. Build OpenOCD for the FT22322 interface $ pwd /home/OpenOCD/openocd $ ./bootstrap Jim is a tiny version of the Tcl scripting language. It is needed by more recent versions of OpenOCD. Build libjim.a using the following instructions: $ git submodule init $ git submodule update $ cd jimtcl $ ./configure --with-jim-ext=nvp $ make $ make install Configure OpenOCD: $ ./configure --enable-maintainer-mode --disable-werror --disable-shared \ --enable-ft2232_ftd2xx --with-ftd2xx-win32-zipdir=/home/OpenOCD/ftd2xx \ LDFLAGS="-L/home/OpenOCD/openocd/jimtcl" Then build OpenOCD and its HTML documentation: $ make $ make html The result of the first make will be the "openocd.exe" will be created in the folder /home/openocd/src. The following command will install OpenOCD to a standard location (/usr/local/bin) using using this command: $ make install Helper Scripts. I have been using the Olimex ARM-USB-OCD JTAG debugger with the LPC1766-STK (http://www.olimex.com). OpenOCD requires a configuration file. I keep the one I used last here: configs/olimex-lpc1766stk/tools/olimex.cfg However, the "correct" configuration script to use with OpenOCD may change as the features of OpenOCD evolve. So you should at least compare that olimex.cfg file with configuration files in /usr/local/share/openocd/scripts/target (or /home/OpenOCD/openocd/tcl/target). As of this writing, there is no script for the lpc1766, but the lpc1768 configurtion can be used after changing the flash size to 256Kb. That is, change: flash bank $_FLASHNAME lpc2000 0x0 0x80000 0 0 $_TARGETNAME ... To: flash bank $_FLASHNAME lpc2000 0x0 0x40000 0 0 $_TARGETNAME ... There is also a script on the tools/ directory that I use to start the OpenOCD daemon on my system called oocd.sh. That script will probably require some modifications to work in another environment: - Possibly the value of OPENOCD_PATH and TARGET_PATH - It assumes that the correct script to use is the one at configs/olimex-lpc1766stk/tools/olimex.cfg Starting OpenOCD Then you should be able to start the OpenOCD daemon like: configs/olimex-lpc1766stk/tools/oocd.sh $PWD If you use the setenv.sh file, that the path to oocd.sh will be added to your PATH environment variabl. So, in that case, the command simplifies to just: oocd.sh $PWD Where it is assumed that you are executing oocd.sh from the top-level directory where NuttX is installed. $PWD will be the path to the top-level NuttX directory. Connecting GDB Once the OpenOCD daemon has been started, you can connect to it via GDB using the following GDB command: arm-elf-gdb (gdb) target remote localhost:3333 And you can load the NuttX ELF file: (gdb) symbol-file nuttx (gdb) load nuttx OpenOCD will support several special 'monitor' commands. These GDB commands will send comments to the OpenOCD monitor. Here are a couple that you will need to use: (gdb) monitor reset (gdb) monitor halt The MCU must be halted prior to loading code. Reset will restart the processor after loading code. The 'monitor' command can be abbreviated as just 'mon'. Olimex LPC1766-STK Configuration Options ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ CONFIG_ARCH - Identifies the arch/ subdirectory. This should be set to: CONFIG_ARCH=arm CONFIG_ARCH_family - For use in C code: CONFIG_ARCH_ARM=y CONFIG_ARCH_architecture - For use in C code: CONFIG_ARCH_CORTEXM3=y CONFIG_ARCH_CHIP - Identifies the arch/*/chip subdirectory CONFIG_ARCH_CHIP=lpc17xx CONFIG_ARCH_CHIP_name - For use in C code to identify the exact chip: CONFIG_ARCH_CHIP_LPC1766=y CONFIG_ARCH_BOARD - Identifies the configs subdirectory and hence, the board that supports the particular chip or SoC. CONFIG_ARCH_BOARD=olimex-lpc1766stk (for the Olimex LPC1766-STK) CONFIG_ARCH_BOARD_name - For use in C code CONFIG_ARCH_BOARD_LPC1766STK=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_DRAM_SIZE - Describes the installed DRAM (CPU SRAM in this case): CONFIG_DRAM_SIZE=(32*1024) (32Kb) There is an additional 32Kb of SRAM in AHB SRAM banks 0 and 1. CONFIG_DRAM_START - The start address of installed DRAM CONFIG_DRAM_START=0x10000000 CONFIG_DRAM_END - Last address+1 of installed RAM CONFIG_DRAM_END=(CONFIG_DRAM_START+CONFIG_DRAM_SIZE) CONFIG_ARCH_IRQPRIO - The LPC17xx supports interrupt prioritization CONFIG_ARCH_IRQPRIO=y 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. Individual subsystems can be enabled: CONFIG_LPC17_MAINOSC=y CONFIG_LPC17_PLL0=y CONFIG_LPC17_PLL1=n CONFIG_LPC17_ETHERNET=n CONFIG_LPC17_USBHOST=n CONFIG_LPC17_USBOTG=n CONFIG_LPC17_USBDEV=n CONFIG_LPC17_UART0=y CONFIG_LPC17_UART1=n CONFIG_LPC17_UART2=n CONFIG_LPC17_UART3=n CONFIG_LPC17_CAN1=n CONFIG_LPC17_CAN2=n CONFIG_LPC17_SPI=n CONFIG_LPC17_SSP0=n CONFIG_LPC17_SSP1=n CONFIG_LPC17_I2C0=n CONFIG_LPC17_I2C1=n CONFIG_LPC17_I2S=n CONFIG_LPC17_TMR0=n CONFIG_LPC17_TMR1=n CONFIG_LPC17_TMR2=n CONFIG_LPC17_TMR3=n CONFIG_LPC17_RIT=n CONFIG_LPC17_PWM=n CONFIG_LPC17_MCPWM=n CONFIG_LPC17_QEI=n CONFIG_LPC17_RTC=n CONFIG_LPC17_WDT=n CONFIG_LPC17_ADC=n CONFIG_LPC17_DAC=n CONFIG_LPC17_GPDMA=n CONFIG_LPC17_FLASH=n LPC17xx specific device driver settings 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 LPC17xx specific PHY/Ethernet device driver settings. These setting also require CONFIG_NET and CONFIG_LPC17_ETHERNET. CONFIG_PHY_KS8721 - Selects Micrel KS8721 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_EMACRAM_SIZE - Size of EMAC RAM. Default: 16Kb CONFIG_NET_NTXDESC - Configured number of Tx descriptors. Default: 18 CONFIG_NET_NRXDESC - Configured number of Rx descriptors. Default: 18 CONFIG_NET_PRIORITY - Ethernet interrupt priority. The is default is the higest priority. CONFIG_NET_WOL - Enable Wake-up on Lan (not fully implemented). CONFIG_NET_REGDEBUG - Enabled low level register debug. Also needs CONFIG_DEBUG. CONFIG_NET_DUMPPACKET - Dump all received and transmitted packets. Also needs CONFIG_DEBUG. CONFIG_NET_HASH - Enable receipt of near-perfect match frames. CONFIG_NET_MULTICAST - Enable receipt of multicast (and unicast) frames. Automatically set if CONFIG_NET_IGMP is selected. LPC17xx USB Configuration CONFIG_LPC17_USBDEV_FRAME_INTERRUPT Handle USB Start-Of-Frame events. Enable reading SOF from interrupt handler vs. simply reading on demand. Probably a bad idea... Unless there is some issue with sampling the SOF from hardware asynchronously. CONFIG_LPC17_USBDEV_EPFAST_INTERRUPT Enable high priority interrupts. I have no idea why you might want to do that CONFIG_LPC17_USBDEV_NDMADESCRIPTORS Number of DMA descriptors to allocate in SRAM. CONFIG_LPC17_USBDEV_DMA Enable lpc17xx-specific DMA support Configurations ^^^^^^^^^^^^^^ Each Olimex LPC1766-STK configuration is maintained in a sudirectory and can be selected as follow: cd tools ./configure.sh olimex-lpc1766stk/<subdir> cd - . ./setenv.sh Where <subdir> is one of the following: nsh: Configures the NuttShell (nsh) located at examples/nsh. The Configuration enables both the serial and telnet NSH interfaces. Support for the board's SPI-based MicroSD card is included (but not passing tests as of this writing). ostest: This configuration directory, performs a simple OS test using examples/ostest. thttpd: This builds the THTTPD web server example using the THTTPD and the examples/thttpd application. usbserial: This configuration directory exercises the USB serial class driver at examples/usbserial. See examples/README.txt for more information. usbstorage: This configuration directory exercises the USB mass storage class driver at examples/usbstorage. See examples/README.txt for more information.