README
======
This README file discusses the port of NuttX to the Atmel SAM V71 Xplained
Ultra Evaluation Kit (SAMV71-XULT). This board features the ATSAMV71Q21 Cortex-M7
microcontroller.
Contents
========
- Board Features
- Serial Console
- LEDs and Buttons
- Debugging
- Configurations
Board Features
==============
- ATSAMV71Q21 microcontroller: Cortex-M7, 300MHz, 2MiB FLASH, 384KiB SRAM,
I/D-caches
- One mechanical reset button
- One power switch button
- Two mechanical user pushbuttons
- Two yellow user LEDs
- Supercap backup
- 12.0 MHz crystal
- 32.768 kHz crystal
- 2 MB SDRAM
- 2 MB QSPI Flash
- IEEE 802.3az 10Base-T/100Base-TX Ethernet RMII PHY
- AT24MAC402 256KByte EEPROM with EUI-48 address
- WM8904 stereo audio codec
- ATA6561 CAN Transceiver
- SD Card connector with SDIO support
- Camera interface connector
- MediaLB connector
- Two Xplained Pro extension headers
- One Xplained Pro LCD header
- Coresight 20 connector for 4-bit ETM
- Arduino due compatible shield connectors
- External debugger connector
- USB interface, device and host mode
- Embedded Debugger with Data Gateway Interface and Virtual COM port (CDC)
- External power input (5-14V) or USB powered
See the Atmel webite for further information about this board:
- http://www.atmel.com/tools/atsamv71-xult.aspx
Serial Console
==============
The SAMV71-XULT has no on-board RS-232 drivers so it will be necessary to
use either the VCOM or an external RS-232 driver. Here are some options.
- Arduino Serial Shield: One option is to use an Arduino-compatible
serial shield. This will use the RXD and TXD signals available at pins
0 an 1, respectively, of the Arduino "Digital Low" connector. On the
SAMV71-XULT board, this corresponds to UART3:
------ ------ ------- ------- --------
Pin on SAMV71 Arduino Arduino SAMV71
J503 PIO Name Pin Function
------ ------ ------- ------- --------
1 PD28 RX0 0 URXD3
2 PD30 TX0 1 UTXD3
------ ------ ------- ------- --------
- SAMV7-XULT EXTn connectors. USART pins are also available the EXTn
connectors. The following are labelled in the User Guide for USART
functionality:
---- -------- ------ --------
EXT1 EXTI1 SAMV71 SAMV71
Pin Name PIO Function
---- -------- ------ --------
13 USART_RX PB00 RXD0
14 USART_TX PB01 TXD0
---- -------- ------ --------
EXT2 EXTI2 SAMV71 SAMV71
Pin Name PIO Function
---- -------- ------ --------
13 USART_RX PA21 RXD1
14 USART_TX PB04 TXD1
- VCOM. The Virtual Com Port gateway is available on USART1:
------ --------
SAMV71 SAMV71
PIO Function
------ --------
PB04 TXD1
PA21 RXD1
------ --------
Any of these options can be selected as the serial console by:
1. Enabling the UART/USART peripheral in the
"System Type -> Peripheral Selection" menu, then
2. Configuring the peripheral in the "Drivers -> Serial Configuration"
menu.
LEDs and Buttons
================
LEDs
----
There are two yellow LED available on the SAM V71 Xplained Ultra board that
can be turned on and off. The LEDs can be activated by driving the
connected I/O line to GND.
------ ----------- ---------------------
SAMV71 Function Shared functionality
PIO
------ ----------- ---------------------
PA23 Yellow LED0 EDBG GPIO
PC09 Yellow LED1 LCD, and Shield
------ ----------- ---------------------
These LEDs are not used by the board port unless CONFIG_ARCH_LEDS is
defined. In that case, the usage by the board port is defined in
include/board.h and src/sam_autoleds.c. The LEDs are used to encode
OS-related events as follows:
------------------- ----------------------- -------- --------
SYMBOL Meaning LED state
LED0 LED1
------------------- ----------------------- -------- --------
LED_STARTED NuttX has been started OFF OFF
LED_HEAPALLOCATE Heap has been allocated OFF OFF
LED_IRQSENABLED Interrupts enabled OFF OFF
LED_STACKCREATED Idle stack created ON OFF
LED_INIRQ In an interrupt No change
LED_SIGNAL In a signal handler No change
LED_ASSERTION An assertion failed No change
LED_PANIC The system has crashed N/C Blinking
LED_IDLE MCU is is sleep mode Not used
------------------- ----------------------- -------- --------
Thus if LED0 is statically on, NuttX has successfully booted and is,
apparently, running normally. If LED1 is flashing at approximately
2Hz, then a fatal error has been detected and the system has halted.
NOTE: That LED0 is not used after completion of booting and may
be used by other board-specific logic.
Buttons
-------
SAM V71 Xplained Ultra contains three mechanical buttons. One button is the
RESET button connected to the SAM V71 reset line and the others are generic
user configurable buttons. When a button is pressed it will drive the I/O
line to GND.
------ ----------- ---------------------
SAMV71 Function Shared functionality
PIO
------ ----------- ---------------------
RESET RESET Trace, Shield, and EDBG
PA09 SW0 EDBG GPIO and Camera
PB12 SW1 EDBG SWD and Chip Erase
------ ----------- ---------------------
NOTES:
- There are no pull-up resistors connected to the generic user buttons so
it is necessary to enable the internal pull-up in the SAM V71 to use the
button.
- PB12 is set up as a system flash ERASE pin when the firmware boots. To
use the SW1, PB12 has to be configured as a normal regular I/O pin in
the MATRIX module. For more information see the SAM V71 datasheet.
Debugging
=========
The on-board EDBG appears to work only with Atmel Studio. You can however,
simply connect a SAM-ICE or J-Link to the JTAG/SWD connector on the board
and that works great. The only tricky thing is getting the correct
orientation of the JTAG connection.
I have been using Atmel Studio to write code to flash then I use the Segger
J-Link GDB server to debug. I have been using the 'Device Programming' I
available under the Atmel Studio 'Tool' menu. I have to disconnect the
SAM-ICE while programming with the EDBG. I am sure that you could come up
with a GDB server-only solution if you wanted.
I run GDB like this from the directory containing the NuttX ELF file:
arm-none-eabi-gdb
(gdb) target remote localhost:2331
(gdb) mon reset
(gdb) file nuttx
(gdb) ... start debugging ...
Configurations
==============
Information Common to All Configurations
----------------------------------------
Each SAMV71-XULT configuration is maintained in a sub-directory and
can be selected as follow:
cd tools
./configure.sh samv71-xult/<subdir>
cd -
. ./setenv.sh
Before sourcing the setenv.sh file above, you should examine it and perform
edits as necessary so that TOOLCHAIN_BIN is the correct path to the directory
than holds your toolchain binaries.
And then build NuttX by simply typing the following. At the conclusion of
the make, the nuttx binary will reside in an ELF file called, simply, nuttx.
make oldconfig
make
The <subdir> that is provided above as an argument to the tools/configure.sh
must be is one of the following.
NOTES:
1. These configurations use the mconf-based configuration tool. To
change any of these configurations using that tool, you should:
a. Build and install the kconfig-mconf tool. See nuttx/README.txt
and misc/tools/
b. Execute 'make menuconfig' in nuttx/ in order to start the
reconfiguration process.
2. Unless stated otherwise, all configurations generate console
output on USART3 (i.e., for the Arduino serial shield).
3. All of these configurations are set up to build under Windows using the
"GNU Tools for ARM Embedded Processors" that is maintained by ARM
(unless stated otherwise in the description of the configuration).
https://launchpad.net/gcc-arm-embedded
As of this writing (2015-03-11), full support is difficult to find
for the Cortex-M&, but is supported by at least this realeasse of
the ARM GNU tools:
https://launchpadlibrarian.net/192228215/release.txt
That toolchain selection can easily be reconfigured using
'make menuconfig'. Here are the relevant current settings:
Build Setup:
CONFIG_HOST_WINDOWS=y : Window environment
CONFIG_WINDOWS_CYGWIN=y : Cywin under Windows
System Type -> Toolchain:
CONFIG_ARMV7M_TOOLCHAIN_GNU_EABIW=y : GNU ARM EABI toolchain
Configuration sub-directories
-----------------------------
nsh:
Configures the NuttShell (nsh) located at examples/nsh.
NOTES:
1. The serial console is configured by default for use with and Arduino
serial shield (UART3). You will need to reconfigure if you will
to use a different U[S]ART.
2. Default stack sizes are large and should really be tuned to reduce
the RAM footprint:
CONFIG_ARCH_INTERRUPTSTACK=2048
CONFIG_IDLETHREAD_STACKSIZE=1024
CONFIG_USERMAIN_STACKSIZE=2048
CONFIG_PTHREAD_STACK_DEFAULT=2048
... and others ...
3. NSH built-in applications are supported.
Binary Formats:
CONFIG_BUILTIN=y : Enable support for built-in programs
Application Configuration:
CONFIG_NSH_BUILTIN_APPS=y : Enable starting apps from NSH command line
4. Performance-related Configuration settings:
CONFIG_ARMV7M_ICACHE=y : Instruction cache is enabled
CONFIG_ARMV7M_DCACHE=y : Data cache is enabled
# CONFIG_ARCH_FPU is not set : Can be enabled, not verified
# CONFIG_ARMV7M_ITCM is not set : Support not yet in place
# CONFIG_ARMV7M_DTCM is not set : Support not yet in place
