From 3b6e63199a7d9a9a5ed62d55847fce0fb5b5e02c Mon Sep 17 00:00:00 2001
From: Gregory Nutt <gnutt@nuttx.org>
Date: Wed, 9 Oct 2013 07:35:00 -0600
Subject: [PATCH] Add option to enable Aduino Due specific logic, like pull-up
 on UART0 RXD.  Suggested by gdi@embedders.org

---
 ChangeLog                           |  5 +++++
 configs/arduino-due/Kconfig         |  8 ++++++++
 configs/arduino-due/README.txt      | 12 ++++++++++++
 configs/arduino-due/include/board.h | 26 ++++++++++++++++++++++++++
 4 files changed, 51 insertions(+)

diff --git a/ChangeLog b/ChangeLog
index 1796b3be24..a714d687f5 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -5726,4 +5726,9 @@
 	  incorporated into the build system (but still untested (2013-10-8).
 	* configs/sama5d3x-ek/nx:  Add an examples/nx configuratino that
 	  will be used for the SAMA5 LCD bring-up (2013-10-8).
+	* configs/arduino-due/Kconfig and include/board.h:  Add configuration
+	  to select revision 3 of the Arduino Due which has some small
+	  but important differences.  Suggested by gdi@embedders.org.
 
+D
+	  differences 
diff --git a/configs/arduino-due/Kconfig b/configs/arduino-due/Kconfig
index 5330ae2a4c..7fdfd6f361 100644
--- a/configs/arduino-due/Kconfig
+++ b/configs/arduino-due/Kconfig
@@ -5,6 +5,14 @@
 
 if ARCH_BOARD_ARDUINO_DUE
 
+config ADRUINO_DUE_REV3
+	bool "Rev 3"
+	default n
+	---help---
+		This port was performed on the Aduino Due Rev 2 board.  Differences
+		with the Arduino Due Rev 3 board have been reported.  This selection
+		will enable work arounds specifically for the Rev 3 board.
+
 config ARDUINO_ITHEAD_TFT
 	bool "ITEAD 2.4 inch TFT w/Touch"
 	default n
diff --git a/configs/arduino-due/README.txt b/configs/arduino-due/README.txt
index 1fbde5ea35..923db50542 100644
--- a/configs/arduino-due/README.txt
+++ b/configs/arduino-due/README.txt
@@ -13,6 +13,7 @@ Contents
 ^^^^^^^^
 
   - PIO Pin Usage
+  - Rev 2 vs. Rev 3
   - ITEAD 2.4" TFT with Touch
   - Development Environment
   - GNU Toolchain Options
@@ -105,6 +106,17 @@ PIO Pin Usage
   PD31  N/A5        N/A          PE31  N/A          N/A         PF31  N/A         N/A
   ----- ---------- ---- -------- ----- ------------ ---- ------ ----- ----------- ---- ---------
 
+Rev 2 vs. Rev 3
+^^^^^^^^^^^^^^^
+
+  This port was performed on the Arduino Due Rev 2 board.  NuttX users
+  have reported issues with the serial port on his Aduino Due Rev 3 board.
+  That problem was resolved as by configuring the UART0 RXD with a pull-up
+  (see include/board.h).  That fix as well as any others that we may find
+  will be enabled by selecting
+
+    CONFIG_ADRUINO_DUE_REV3=y
+
 ITEAD 2.4" TFT with Touch
 ^^^^^^^^^^^^^^^^^^^^^^^^^
 
diff --git a/configs/arduino-due/include/board.h b/configs/arduino-due/include/board.h
index 43d3fe0167..b9059131e3 100644
--- a/configs/arduino-due/include/board.h
+++ b/configs/arduino-due/include/board.h
@@ -195,6 +195,32 @@
 /* Button definitions ***************************************************************/
 /*   There are no buttons on the Arduino Due board. */
 
+/* GPIO pin configurations **********************************************************/
+
+#ifdef CONFIG_ADRUINO_DUE_REV3
+/* This port was performed on the Arduino Due Rev 2 board.  A NuttX user reported
+ * issues with the serial port on his Aduino Due Rev 3 board.  That problem was
+ * resolved as follows:
+ *
+ *  "... The issue was in my hardware. I found the difference between Arduino
+ *   Due shematics (revision R2) and actual PCB layout of my Arduino (revision
+ *   R3). On a schematics which I download from arduino.cc was shown that 2nd
+ *   pin of IC10 is connected to the ground, but on my Arduino the 2nd pin
+ *   of IC10 was connected to its 1st pin instead of ground and in my case
+ *   IC10 works in open-drain mode, but RX0 pin on SAM3x doesn't have pull-up
+ *   and thus TX signal from AtMega16U2 can't reach the SAM3x input pin, on
+ *   this pin always '0'.
+ *
+ *  "My solution is to enable internal pull-up in SAM3x. ...
+ *   Now shell console on UART0 (via USB programming connector) of Arduino Due
+ *   Due works as expected."
+ */
+
+#  undef  GPIO_UART0_RXD
+#  define GPIO_UART0_RXD  (GPIO_PERIPHA | GPIO_CFG_DEFAULT | GPIO_PORT_PIOA | \
+                           GPIO_PIN8 | GPIO_CFG_PULLUP)
+#endif
+
 /************************************************************************************
  * Public Data
  ************************************************************************************/