README
^^^^^^

This README discusses issues unique to NuttX configurations for the
Atmel SAM4S Xplained development board. This board features the
ATSAM4S32C MCU with 1MB FLASH and 128KB.

The SAM4S Xplained features:

- 120 MHz Cortex-M4 with MPU
- 12MHz crystal (no 32.768KHz crystal)
- Segger J-Link JTAG emulator on-board for program and debug
- MICRO USB A/B connector for USB connectivity
- IS66WV51216DBLL ISSI SRAM 8Mb 512K x 16 55ns PSRAM 2.5v-3.6v
- Four Atmel QTouch buttons
- External voltage input
- Two LEDs, one controllable from software
- Xplained expansion headers
- Footprint for external serial Flash (not fitted)

Contents
^^^^^^^^

- PIO Muliplexing
- Buttons and LEDs
- Serial Consoles
- SAM4S Xplained-specific Configuration Options
- Configurations

PIO Muliplexing
^^^^^^^^^^^^^^^

PA0 SMC_A17 PB0 J2.3 default PC0 SMC_D0
PA1 SMC_A18 PB1 J2.4 PC1 SMC_D1
PA2 J3.7 default PB2 J1.3 & J4.3 PC2 SMC_D2
PA3 J1.1 & J4.1 PB3 J1.4 & J4.4 PC3 SMC_D3
PA4 J1.2 & J4.2 PB4 JTAG PC4 SMC_D4
PA5 User_button BP2 PB5 JTAG PC5 SMC_D5
PA6 J3.7 optional PB6 JTAG PC6 SMC_D6
PA7 CLK_32K PB7 JTAG PC7 SMC_D7
PA8 CLK_32K PB8 CLK_12M PC8 SMC_NWE
PA9 RX_UART0 PB9 CLK_12M PC9 Power on detect
PA10 TX_UART0 PB10 USB_DDM PC10 User LED D9
PA11 J3.2 default PB11 USB_DDP PC11 SMC_NRD
PA12 MISO PB12 ERASE PC12 J2.2
PA13 MOSI PB13 J2.3 optional PC13 J2.7
PA14 SPCK PB14 N/A PC14 SMC_NCS0
PA15 J3.5 PC15 SMC_NSC1
PA16 J3.6 PC16 N/A
PA17 J2.5 PC17 User LED D10
PA18 J3.4 & SMC_A14 PC18 SMC_A0
PA19 J3.4 optional & SMC_A15 PC19 SMC_A1
PA20 J3.1 & SMC_A16 PC20 SMC_A2
PA21 J2.6 PC21 SMC_A3
PA22 J2.1 PC22 SMC_A4
PA23 J3.3 PC23 SMC_A5
PA24 TSLIDR_SL_SN PC24 SMC_A6
PA25 TSLIDR_SL_SNSK PC25 SMC_A7
PA26 TSLIDR_SM_SNS PC26 SMC_A8
PA27 TSLIDR_SM_SNSK PC27 SMC_A9
PA28 TSLIDR_SR_SNS PC28 SMC_A10
PA29 TSLIDR_SR_SNSK PC29 SMC_A11
PA30 J4.5 PC30 SMC_A12
PA31 J1.5 PC31 SMC_A13

Buttons and LEDs
^^^^^^^^^^^^^^^^

Buttons
-------
The SAM4S Xplained has two mechanical buttons. One button is the RESET button
connected to the SAM4S reset line and the other is a generic user configurable
button labeled BP2 and connected to GPIO PA5. When a button is pressed it
will drive the I/O line to GND.

LEDs
----
There is one LED on board the SAM4S Xplained board Pro that can be
controlled by software in the SAM4S:

LED GPIO
---------------- -----
LED0 Yellow LED PC23

It can be illuminated by driving the GPIO output to ground (low).

If CONFIG_ARCH_LEDs is defined, then NuttX will control the LED on
board the SAM4S Xplained Pro, otherwise it can controlled by the user
with functions defined into boards file src/sam_userleds.c.

The user LED is 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_leds.c. The LEDs are used to encode OS-
related events as follows:

SYMBOL Meaning LED state
LED0
------------------- ----------------------- -----------
LED_STARTED NuttX has been started OFF
LED_HEAPALLOCATE Heap has been allocated OFF
LED_IRQSENABLED Interrupts enabled OFF
LED_STACKCREATED Idle stack created ON
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 OFF
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 LED0 is flashing at approximately
2Hz, then a fatal error has been detected and the system has halted.

Serial Consoles
^^^^^^^^^^^^^^^

UART1
-----
If you have a TTL to RS-232 convertor then this is the most convenient
serial console to use. UART1 is the default in all of these
configurations.

UART1 RXD PB2 J1 pin 3 J4 pin 3
UART1 TXD PB3 J1 pin 4 J4 pin 4
GND J1 pin 9 J4 pin 9
Vdd J1 pin 10 J4 pin 10

USART1
------
USART1 is another option:

USART1 RXD PA21 J2 pin 6
USART1 TXD PA22 J2 pin 1
GND J2 pin 9
Vdd J2 pin 10

Virtual COM Port
----------------
Yet another option is to use UART0 and the virtual COM port. This
option may be more convenient for long term development, but was
painful to use during board bring-up.

The SAM4S Xplained contains an Embedded Debugger (EDBG) that can be
used to program and debug the ATSAM4S16C using Serial Wire Debug (SWD).
The Embedded debugger also include a Virtual Com port interface over
USART1. Virtual COM port connections:

AT91SAM4S16 ATSAM3U4CAU
-------------- --------------
PA9 RX_UART0 PA9_4S PA12
PA10 TX_UART0 RX_3U PA11

SAM4S Xplained-specific 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_CORTEXM4=y

CONFIG_ARCH_CHIP - Identifies the arch/*/chip subdirectory

CONFIG_ARCH_CHIP="sam34"

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

CONFIG_ARCH_CHIP_SAM34
CONFIG_ARCH_CHIP_SAM4S
CONFIG_ARCH_CHIP_ATSAM4D32C

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

CONFIG_ARCH_BOARD=sam4s-xplained-pro (for the SAM4S Xplained Pro development board)

CONFIG_ARCH_BOARD_name - For use in C code

CONFIG_ARCH_BOARD_SAM4S_XPLAINED_PRO=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 (SRAM in this case):

CONFIG_RAM_SIZE=0x00008000 (32Kb)

CONFIG_RAM_START - The start address of installed DRAM

CONFIG_RAM_START=0x20000000

CONFIG_ARCH_IRQPRIO - The SAM4S 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.

Individual subsystems can be enabled:

CONFIG_SAM34_RTC - Real Time Clock
CONFIG_SAM34_RTT - Real Time Timer
CONFIG_SAM34_WDT - Watchdog Timer
CONFIG_SAM34_UART0 - UART 0
CONFIG_SAM34_UART1 - UART 1
CONFIG_SAM34_SMC - Static Memory Controller
CONFIG_SAM34_USART0 - USART 0
CONFIG_SAM34_USART1 - USART 1
CONFIG_SAM34_HSMCI - High Speed Multimedia Card Interface
CONFIG_SAM34_TWI0 - Two-Wire Interface 0
CONFIG_SAM34_TWI1 - Two-Wire Interface 1
CONFIG_SAM34_SPI0 - Serial Peripheral Interface
CONFIG_SAM34_SSC - Synchronous Serial Controller
CONFIG_SAM34_TC0 - Timer Counter 0
CONFIG_SAM34_TC1 - Timer Counter 1
CONFIG_SAM34_TC2 - Timer Counter 2
CONFIG_SAM34_TC3 - Timer Counter 3
CONFIG_SAM34_TC4 - Timer Counter 4
CONFIG_SAM34_TC5 - Timer Counter 5
CONFIG_SAM34_ADC12B - 12-bit Analog To Digital Converter
CONFIG_SAM34_DACC - Digital To Analog Converter
CONFIG_SAM34_PWM - Pulse Width Modulation
CONFIG_SAM34_CRCCU - CRC Calculation Unit
CONFIG_SAM34_ACC - Analog Comparator
CONFIG_SAM34_UDP - USB Device Port

Some subsystems can be configured to operate in different ways. The drivers
need to know how to configure the subsystem.

CONFIG_GPIOA_IRQ
CONFIG_GPIOB_IRQ
CONFIG_GPIOC_IRQ
CONFIG_USART0_SERIALDRIVER
CONFIG_USART1_SERIALDRIVER
CONFIG_USART2_SERIALDRIVER
CONFIG_USART3_SERIALDRIVER

ST91SAM4S specific device driver settings

CONFIG_U[S]ARTn_SERIAL_CONSOLE - selects the USARTn (n=0,1,2,3) or UART
m (m=4,5) for the console and ttys0 (default is the USART1).
CONFIG_U[S]ARTn_RXBUFSIZE - Characters are buffered as received.
This specific the size of the receive buffer
CONFIG_U[S]ARTn_TXBUFSIZE - Characters are buffered before
being sent. This specific the size of the transmit buffer
CONFIG_U[S]ARTn_BAUD - The configure BAUD of the UART. Must be
CONFIG_U[S]ARTn_BITS - The number of bits. Must be either 7 or 8.
CONFIG_U[S]ARTn_PARTIY - 0=no parity, 1=odd parity, 2=even parity
CONFIG_U[S]ARTn_2STOP - Two stop bits

Configurations
^^^^^^^^^^^^^^

Each SAM4S Xplained configuration is maintained in a sub-directory and
can be selected as follow:

tools/configure.shsam4s-xplained-pro/

Before building, make sure the PATH environment variable includes 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

The 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
see additional README.txt files in the NuttX tools repository.

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

2. Unless stated otherwise, all configurations generate console
output on UART1 which is available on J1 or J4 (see the
section "Serial Consoles" above). USART1 or the virtual COM
port on UART0 are options. The virtual COM port could
be used, for example, by reconfiguring to use UART0 like:

System Type -> AT91SAM3/4 Peripheral Support
CONFIG_SAM_UART0=y
CONFIG_SAM_UART1=n

Device Drivers -> Serial Driver Support -> Serial Console
CONFIG_UART0_SERIAL_CONSOLE=y

Device Drivers -> Serial Driver Support -> UART0 Configuration
CONFIG_UART0_2STOP=0
CONFIG_UART0_BAUD=115200
CONFIG_UART0_BITS=8
CONFIG_UART0_PARITY=0
CONFIG_UART0_RXBUFSIZE=256
CONFIG_UART0_TXBUFSIZE=256

3. Unless otherwise stated, the configurations are setup for
Linux (or any other POSIX environment like Cygwin under Windows):

Build Setup:
CONFIG_HOST_LINUX=y : Linux or other POSIX environment

4. These configurations use the older, OABI, buildroot toolchain. But
that is easily reconfigured:

System Type -> Toolchain:
CONFIG_ARMV7M_TOOLCHAIN_BUILDROOT=y : Buildroot toolchain
CONFIG_ARMV7M_OABI_TOOLCHAIN=y : Older, OABI toolchain

If you want to use the Atmel GCC toolchain, here are the steps to
do so:

Build Setup:
CONFIG_HOST_WINDOWS=y : Windows
CONFIG_HOST_CYGWIN=y : Using Cygwin or other POSIX environment

System Type -> Toolchain:
CONFIG_ARMV7M_TOOLCHAIN_GNU_EABIW=y : General GCC EABI toolchain under windows

This re-configuration should be done before making NuttX or else the
subsequent 'make' will fail. If you have already attempted building
NuttX then you will have to 1) 'make distclean' to remove the old
configuration, 2) 'tools/configure.sh sam3u-ek/ksnh' to start
with a fresh configuration, and 3) perform the configuration changes
above.

Also, make sure that your PATH variable has the new path to your
Atmel tools. Try 'which arm-none-eabi-gcc' to make sure that you
are selecting the right tool.

See also the "NOTE about Windows native toolchains" in the section call
"GNU Toolchain Options" above.

Configuration sub-directories
-----------------------------

nsh:
This configuration directory will built the NuttShell. See NOTES above.

NOTES:
1. The configuration configuration can be modified to include support
for the on-board SRAM (1MB).

System Type -> External Memory Configuration
CONFIG_SAM34_EXTSRAM0=y : Select SRAM on CS0
CONFIG_SAM34_EXTSRAM0SIZE=1048576 : Size=1MB

Now what are you going to do with the SRAM. There are two choices:

a) To enable the NuttX RAM test that may be used to verify the
external SRAM:

System Type -> External Memory Configuration
CONFIG_SAM34_EXTSRAM0HEAP=n : Don't add to heap

Application Configuration -> System NSH Add-Ons
CONFIG_SYSTEM_RAMTEST=y : Enable the RAM test built-in

In this configuration, the SDRAM is not added to heap and so is
not excessible to the applications. So the RAM test can be
freely executed against the SRAM memory beginning at address
0x6000:0000 (CS0).

nsh> ramtest -h
Usage: [-w|h|b]

Where:
starting address of the test.
number of memory locations (in bytes).
-w Sets the width of a memory location to 32-bits.
-h Sets the width of a memory location to 16-bits (default).
-b Sets the width of a memory location to 8-bits.

To test the entire external SRAM:

nsh> ramtest 60000000 1048576
RAMTest: Marching ones: 60000000 1048576
RAMTest: Marching zeroes: 60000000 1048576
RAMTest: Pattern test: 60000000 1048576 55555555 aaaaaaaa
RAMTest: Pattern test: 60000000 1048576 66666666 99999999
RAMTest: Pattern test: 60000000 1048576 33333333 cccccccc
RAMTest: Address-in-address test: 60000000 1048576

b) To add this RAM to the NuttX heap, you would need to change the
configuration as follows:

System Type -> External Memory Configuration
CONFIG_SAM34_EXTSRAM0HEAP=y : Add external RAM to heap

Memory Management
-CONFIG_MM_REGIONS=1 : Only the internal SRAM
+CONFIG_MM_REGIONS=2 : Also include external SRAM