README ^^^^^^
This README discusses issues unique to NuttX configurations for the Atmel SAM4S Xplained development board. This board features the ATSAM4S16C 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
- Four LEDs, two 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 are four LEDs on board the SAM4X Xplained board, two of these can be controlled by software in the SAM4S:
LED GPIO
---------------- -----
D9 Yellow LED PC10
D10 Yellow LED PC17
Both can be illuminated by driving the GPIO output to ground (low).
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_leds.c. The LEDs are used to encode OS-related events as follows:
SYMBOL Meaning LED state
D9 D10
------------------- ----------------------- -------- --------
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 OFF Blinking
LED_IDLE MCU is is sleep mode Not used
Thus if D9 is statically on, NuttX has successfully booted and is, apparently, running normmally. If D10 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 converter 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_ATSAM4S16C
CONFIG_ARCH_BOARD - Identifies the boards/ subdirectory and hence, the board that supports the particular chip or SoC.
CONFIG_ARCH_BOARD=sam4s-xplained (for the SAM4S Xplained development board)
CONFIG_ARCH_BOARD_name - For use in C code
CONFIG_ARCH_BOARD_SAM4S_XPLAINED=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_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_SAM34_GPIOA_IRQ
CONFIG_SAM34_GPIOB_IRQ
CONFIG_SAM34_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:<subdir>
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 <subdir> that is provided above as an argument to the tools/configure.sh must be is one of the following.
NOTES:
- 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.
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
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
These configurations use the older, OABI, buildroot toolchain. But that is easily reconfigured:
System Type -> Toolchain: CONFIG_ARM_TOOLCHAIN_BUILDROOT=y : Buildroot toolchain CONFIG_ARM_TOOLCHAIN_BUILDROOT_OABI=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_ARM_TOOLCHAIN_GNU_EABI=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_TESTING_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: <noname> [-w|h|b] <hex-address> <decimal-size>
Where:
<hex-address> starting address of the test.
<decimal-size> 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