SAMD20: Fixes the problem introduced with the SAML21 integration

configs/samd20-xplained/README.txt

@@ -1,5 +1,5 @@
 README
-^^^^^^
+======
 
 This README discusses issues unique to NuttX configurations for the
 Atmel SAMD20 Xplained Pro development board.  This board features the
@@ -14,9 +14,9 @@ The SAMD20 Xplained Pro Starter Kit may be bundled with three modules:
             logic).
 
 Contents
-^^^^^^^^
+========
 
-  - STATUS
+  - STATUS/ISSUES
   - Modules
   - Development Environment
   - GNU Toolchain Options
@@ -28,11 +28,12 @@ Contents
   - SAMD20 Xplained Pro-specific Configuration Options
   - Configurations
 
-    STATUS/ISSUES:
+STATUS/ISSUES
+=============
 
-    1. The FLASH waitstates is set to 2 (see include/board.h).  According to
+    1. The FLASH wait states is set to 2 (see include/board.h).  According to
        the data sheet, it should work at 1 but I sometimes see crashes when
-       the waitstates are set to one (about half of the time) (2014-2-18).
+       the wait states are set to one (about half of the time) (2014-2-18).
 
     2. Garbage appears on the display sometimes after a reset (maybe 20% of
        the time) or after a power cycle (less after a power cycle).  I don't
@@ -62,13 +63,9 @@ Contents
     4. OLED1 module is untested.  These instructions were just lifted from
        the SAM4L Xplained Pro README.txt file.
 
-    5. As of 20154-05-24, this SAMD20 configurations are broken.  This
-       seems to have occurred as a consequence of the SAML21 integration
-       between NuttX-7.9 and NuttX-7.10.  Hence, I expect that the problem
-       is trivial but nevertheless real.
-
 Modules
-^^^^^^^
+=======
+
   The SAMD20 Xplained Pro Starter Kit is bundled with four modules:
 
   I/O1
@@ -270,7 +267,7 @@ Modules
   There is no built-in support for the PROTO1 module.
 
 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
@@ -278,7 +275,7 @@ Development Environment
   environment.
 
 GNU Toolchain Options
-^^^^^^^^^^^^^^^^^^^^^
+=====================
 
 
   The NuttX make system can be configured to support the various different
@@ -334,7 +331,7 @@ GNU Toolchain Options
        MKDEP                = $(TOPDIR)/tools/mknulldeps.sh
 
 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.
@@ -366,7 +363,7 @@ IDEs
   startup object needed by an IDE.
 
 NuttX EABI "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-M0 GCC toolchain (if
@@ -403,7 +400,8 @@ NuttX EABI "buildroot" Toolchain
   building a Cortex-M0 toolchain for Cygwin under Windows.
 
 LEDs
-^^^^
+====
+
   There is one yellow LED available on the SAM D20 Xplained Pro board that
   can be turned on and off. The LED can be activated by driving the connected
   PA14 I/O line to GND.
@@ -427,7 +425,7 @@ LEDs
   2Hz, then a fatal error has been detected and the system has halted.
 
 Serial Consoles
-^^^^^^^^^^^^^^^
+===============
 
   SERCOM4
   ------
@@ -462,28 +460,32 @@ Serial Consoles
     PA25 SERCOM3 / USART RXD
 
 Atmel Studio 6.1
-^^^^^^^^^^^^^^^^
+================
 
   Loading Code into FLASH:
   -----------------------
+
   Tools menus:  Tools -> Device Programming.
 
   Debugging the NuttX Object File
   -------------------------------
+
   1) Rename object file from nutt to nuttx.elf.  That is an extension that
      will be recognized by the file menu.
 
   2) File menu: File -> Open -> Open object file for debugging
+
      - Select nuttx.elf object file
      - Select AT91SAMD20J18
      - Select files for symbols as desired
      - Select debugger
 
   3) Debug menu: Debug -> Start debugging and break
+
      - This will reload the nuttx.elf file into FLASH
 
 SAMD20 Xplained Pro-specific Configuration Options
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+==================================================
 
     CONFIG_ARCH - Identifies the arch/ subdirectory.  This should
        be set to:
@@ -600,7 +602,7 @@ SAMD20 Xplained Pro-specific Configuration Options
     CONFIG_USARTn_2STOP - Two stop bits
 
 Configurations
-^^^^^^^^^^^^^^
+==============
 
   Each SAMD20 Xplained Pro configuration is maintained in a sub-directory and
   can be selected as follow:

configs/saml21-xplained/README.txt

@@ -16,6 +16,7 @@ Contents
   - LEDs and Buttons
   - Serial Consoles
   - Atmel Studio 6.1
+  - JTAG
   - SAML21 Xplained Pro-specific Configuration Options
   - Configurations
 
@@ -491,6 +492,14 @@ Atmel Studio 6.1
   3) Debug menu: Debug -> Start debugging and break
      - This will reload the nuttx.elf file into FLASH
 
+JTAG
+====
+
+  I did all of the debug of the SAML21 Xplained using a Segger J-Link
+  connected to the micro JTAG connector on board the SAML21 Xplained.
+  I used an Olimex ARM-JTAG 20-10 Adapter to connect the J-Link to
+  the SAML21 Xplained.
+
 SAML21 Xplained Pro-specific Configuration Options
 ==================================================