README
======
This README discusses issues unique to NuttX configurations for the
Atmel SAML21 Xplained Pro development board. This board features the
ATSAML21J18A MCU.
Contents
========
- STATUS/ISSUES
- Modules
- Development Environment
- GNU Toolchain Options
- IDEs
- NuttX EABI "buildroot" Toolchain
- LEDs and Buttons
- Serial Consoles
- Atmel Studio 6.1
- JTAG
- SAML21 Xplained Pro-specific Configuration Options
- Configurations
STATUS/ISSUES
=============
- Since this port is a leverage of the SAMD20 Xplained port, some of the
STATUS/ISSUES in the SAMD20 Xplained README.txt may apply here as well.
- 2015-5-26: The basic port is running at 48MHz (using 32.768 XTAL input
and the digital frequency locked loop). The basic NuttShell (NSH)
configuration is working well with the serial console provided by
SERCOM4 as 115200 8N1.
- 2015-6-14: Added a DMAC driver. There is no way to verify it at present
and, hence, depends upon CONFIG_EXPERIMENTAL=y
Modules
=======
There are several I/O modules available that will work with the SAML21
Xplained Pro Starter Kit:
1) I/O1 - An MMC/SD card slot, PWM LED control, ADC light sensor, USART
loopback, TWI AT30TSE758 Temperature sensor.
2) OLED1 - An OLED plus 3 additional switches and 3 additional LEDs
3) PROTO1 - A prototyping board with logic on board (other than power-
related logic).
4) And others. See http://www.atmel.com/products/microcontrollers/avr/xplained.aspx
Some of these are discussed further below.
I/O1
----
The primary function of this module is to provide SD card support, but
the full list of modules features include:
- microSD card connector (SPI interface)
- PWM (LED control)
- ADC (light sensor)
- USART loopback
- TWI AT30TSE758 Temperature sensor with EEPROM
SPI is available on two of the SAML21 Xplained connectors, EXT1 and EXT2.
They mate with the I/O1 connector as indicated in this table.
I/O1 CONNECTOR
----------------- ---------------------- ---------------------- ------------------------------------
I/O1 EXT1 EXT2 Other use of either pin
----------------- ---------------------- ---------------------- ------------------------------------
1 ID 1 1 Communication line to ID chip on
extension board.
----------------- ---------------------- ---------------------- ------------------------------------
2 GND 2 GND 2 GND
----------------- ---------------------- ---------------------- ------------------------------------
3 LIGHT_SENSOR 3 PB05 AIN[13] 3 PA10 AIN[18]
----------------- ---------------------- ---------------------- ------------------------------------
4 LP_OUT 4 PA03 AIN[1] 4 PA11 AIN[19]
----------------- ---------------------- ---------------------- ------------------------------------
5 GPIO1 5 PB06 GPIO 5 PA20 GPIO
----------------- ---------------------- ---------------------- ------------------------------------
6 GPIO2 6 PB07 GPIO 6 PA21 GPIO
----------------- ---------------------- ---------------------- ------------------------------------
7 LED 7 PA12 TCC2/WO[0] 7 PB12 TC4/WO[0]
----------------- ---------------------- ---------------------- ------------------------------------
8 LP_IN 8 PA13 TCC2/WO[1] 8 PB13 TC4/WO[1]
----------------- ---------------------- ---------------------- ------------------------------------
9 TEMP_ALERT 9 PB04 EXTINT[4] 9 PB14 EXTINT[14]
----------------- ---------------------- ---------------------- ------------------------------------
10 microSD_DETECT 10 PA02 GPIO 10 PB15 GPIO
----------------- ---------------------- ---------------------- ------------------------------------
11 TWI SDA 11 PA08 SERCOM2 PAD[0] 11 PA08 SERCOM2 PAD[0] EXT1, EXT2, EXT3 and EDBG
I²C SDA I²C SDA
----------------- ---------------------- ---------------------- ------------------------------------
12 TWI SCL 12 PA09 SERCOM2 PAD[1] 12 PA09 SERCOM2 PAD[1] EXT2, EXT3 and EDBG
I²C SCL I²C SCL
----------------- ---------------------- ---------------------- ------------------------------------
13 USART RX 13 PB09 SERCOM4 PAD[1] 13 PA19 SERCOM1 PAD[3] The SERCOM4 module is shared between
USART RX USART RX EXT1, 2 and 3 USART's, but uses
different pins
----------------- ---------------------- ---------------------- ------------------------------------
14 USART TX 14 PB08 SERCOM4 PAD[0] 14 PA18 SERCOM1 PAD[2] The SERCOM4 module is shared between
USART TX USART TX EXT1, 2 and 3 USART's, but uses
different pins
----------------- ---------------------- ---------------------- ------------------------------------
15 microSD_SS 15 PA05 SERCOM0 PAD[1] 15 PA17 GPIO
SPI SS
----------------- ---------------------- ---------------------- ------------------------------------
16 SPI_MOSI 16 PA06 SERCOM0 PAD[2] 16 PB22 SERCOM5 PAD[2]
SPI MOSI SPI MOSI
----------------- ---------------------- ---------------------- ------------------------------------
17 SPI_MISO 17 PA04 SERCOM0 PAD[0] 17 PB16 SERCOM5 PAD[0]
SPI MISO SPI MISO
----------------- ---------------------- ---------------------- ------------------------------------
18 SPI_SCK 18 PA07 SERCOM0 PAD[3] 18 PB23 SERCOM5 PAD[3]
SPI SCK SPI SCK
----------------- ---------------------- ---------------------- ------------------------------------
19 GND 19 GND GND
----------------- ---------------------- ---------------------- ------------------------------------
20 VCC 20 VCC VCC
----------------- ---------------------- ---------------------- ------------------------------------
The mapping between the I/O1 pins and the SD connector are shown in the
following table.
SD Card Connection
------------------
I/O1 SD PIN Description
---- ---- --- -------------------------------------------------
D2 1 Data line 2 (not used)
15 D3 2 Data line 3. Active low chip select, pulled high
16 CMD 3 Command line, connected to SPI_MOSI.
20 VDD 4
18 CLK 5 Clock line, connected to SPI_SCK.
2/19 GND 6
17 D0 7 Data line 0, connected to SPI_MISO.
D1 8 Data line 1 (not used)
10 SW_A 9 Card detect
2/19 SW_B 10 GND
Card Detect
-----------
When a microSD card is put into the connector SW_A and SW_B are short-
circuited. SW_A is connected to the microSD_DETECT signal. To use this
as a card indicator remember to enable internal pullup in the target
device.
GPIOs
-----
So all that is required to connect the SD is configure the SPI
--- ------------------ ---------------------- -------------------------------------
PIN EXT1 EXT2 Description
--- ------------------ ---------------------- -------------------------------------
15 PA05 SERCOM0 PAD[1] 15 PA17 GPIO Active low chip select OUTPUT, pulled
SPI SS high on board.
--- ------------------ ---------------------- -------------------------------------
10 PA02 GPIO 10 PB15 GPIO Active low card detect INPUT, must
use internal pull-up.
--- ------------------ ---------------------- -------------------------------------
Configuration Options:
----------------------
CONFIG_SAML21_XPLAINED_IOMODULE=y : Informs the system that the
I/O1 module is installed
CONFIG_SAML21_XPLAINED_IOMODULE_EXT1=y : The module is installed in EXT1
CONFIG_SAML21_XPLAINED_IOMODULE_EXT2=y : The mdoule is installed in EXT2
See the set-up in the discussion of the nsh configuration below for other
required configuration options.
NOTE: As of this writing, only the SD card slot is supported in the I/O1
module.
OLED1
-----
This module provides an OLED plus 3 additional switches and 3 additional
LEDs.
OLED1 CONNECTOR
----------------- ---------------------- ---------------------- ------------------------------------
OLED1 EXT1 EXT2 Other use of either pin
----------------- ---------------------- ---------------------- ------------------------------------
1 ID 1 1 Communication line to ID chip on
extension board.
----------------- ---------------------- ---------------------- ------------------------------------
2 GND 2 GND 2 GND
----------------- ---------------------- ---------------------- ------------------------------------
3 BUTTON2 3 PB05 AIN[13] 3 PA10 AIN[18]
----------------- ---------------------- ---------------------- ------------------------------------
4 BUTTON3 4 PA03 AIN[1] 4 PA11 AIN[19]
----------------- ---------------------- ---------------------- ------------------------------------
5 DATA_CMD_SEL 5 PB06 GPIO 5 PA20 GPIO
----------------- ---------------------- ---------------------- ------------------------------------
6 LED3 6 PB07 GPIO 6 PA21 GPIO
----------------- ---------------------- ---------------------- ------------------------------------
7 LED1 7 PA12 TCC2/WO[0] 7 PB12 TC4/WO[0]
----------------- ---------------------- ---------------------- ------------------------------------
8 LED2 8 PA13 TCC2/WO[1] 8 PB13 TC4/WO[1]
----------------- ---------------------- ---------------------- ------------------------------------
9 BUTTON1 9 PB04 EXTINT[4] 9 PB14 EXTINT[14]
----------------- ---------------------- ---------------------- ------------------------------------
10 DISPLAY_RESET 10 PA02 GPIO 10 PB15 GPIO
----------------- ---------------------- ---------------------- ------------------------------------
11 N/C 11 PA08 SERCOM2 PAD[0] 11 PA08 SERCOM2 PAD[0] EXT1, EXT2, EXT3 and EDBG
I²C SDA I²C SDA
----------------- ---------------------- ---------------------- ------------------------------------
12 N/C 12 PA09 SERCOM2 PAD[1] 12 PA09 SERCOM2 PAD[1] EXT2, EXT3 and EDBG
I²C SCL I²C SCL
----------------- ---------------------- ---------------------- ------------------------------------
13 N/C 13 PB09 SERCOM4 PAD[1] 13 PA19 SERCOM1 PAD[3] The SERCOM4 module is shared between
USART RX USART RX EXT1, 2 and 3 USART's, but uses
different pins
----------------- ---------------------- ---------------------- ------------------------------------
14 N/C 14 PB08 SERCOM4 PAD[0] 14 PA18 SERCOM1 PAD[2] The SERCOM4 module is shared between
USART TX USART TX EXT1, 2 and 3 USART's, but uses
different pins
----------------- ---------------------- ---------------------- ------------------------------------
15 DISPLAY_SS 15 PA05 SERCOM0 PAD[1] 15 PA17 GPIO
SPI SS
----------------- ---------------------- ---------------------- ------------------------------------
16 SPI_MOSI 16 PA06 SERCOM0 PAD[2] 16 PB22 SERCOM5 PAD[2]
SPI MOSI SPI MOSI
----------------- ---------------------- ---------------------- ------------------------------------
17 N/C 17 PA04 SERCOM0 PAD[0] 17 PB16 SERCOM5 PAD[0]
SPI MISO SPI MISO
----------------- ---------------------- ---------------------- ------------------------------------
18 SPI_SCK 18 PA07 SERCOM0 PAD[3] 18 PB23 SERCOM5 PAD[3]
SPI SCK SPI SCK
----------------- ---------------------- ---------------------- ------------------------------------
19 GND 19 GND GND
----------------- ---------------------- ---------------------- ------------------------------------
20 VCC 20 VCC VCC
----------------- ---------------------- ---------------------- ------------------------------------
Configuration Options:
----------------------
CONFIG_SAML21_XPLAINED_OLED1MODULE=y : Informs the system that the
I/O1 module is installed
CONFIG_SAML21_XPLAINED_OLED1MODULE_EXT1=y : The module is installed in EXT1
CONFIG_SAML21_XPLAINED_OLED1MODULE_EXT2=y : The mdoule is installed in EXT2
See the set-up in the discussion of the nsh configuration below for other
required configuration options.
PROTO1
------
A prototyping board with logic on board (other than power-related logic).
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
toolchains will likely cause problems. Testing was performed using the Cygwin
environment.
GNU Toolchain Options
=====================
The NuttX make system can be configured to support the various different
toolchain options. All testing has been conducted using the NuttX buildroot
toolchain. To use alternative toolchain, you simply need to add change of
the following configuration options to your .config (or defconfig) file:
CONFIG_ARM_TOOLCHAIN_BUILDROOT=y : NuttX buildroot under Linux or Cygwin (default)
CONFIG_ARM_TOOLCHAIN_GNU_EABI=y : Generic GCC ARM EABI toolchain for Linux
CONFIG_ARM_TOOLCHAIN_GNU_EABI=y : Generic GCC ARM EABI toolchain for Windows
NOTE about Windows native toolchains
------------------------------------
There are basically three kinds of GCC toolchains that can be used:
1. A Linux native toolchain in a Linux environment,
2. The buildroot Cygwin tool chain built in the Cygwin environment,
3. A Windows native toolchain.
There are several limitations to using a Windows based toolchain (#3) in a
Cygwin environment. The three biggest are:
1. The Windows toolchain cannot follow Cygwin paths. Path conversions are
performed automatically in the Cygwin makefiles using the 'cygpath'
utility but you might easily find some new path problems. If so, check
out 'cygpath -w'
2. Windows toolchains cannot follow Cygwin symbolic links. Many symbolic
links are used in NuttX (e.g., include/arch). The make system works
around these problems for the Windows tools by copying directories
instead of linking them. But this can also cause some confusion for
you: For example, you may edit a file in a "linked" directory and find
that your changes had no effect. That is because you are building the
copy of the file in the "fake" symbolic directory. If you use a
Windows toolchain, you should get in the habit of making like this:
make clean_context all
An alias in your .bashrc file might make that less painful.
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.
Makefile Build
--------------
Under Eclipse, it is pretty easy to set up an "empty makefile project" and
simply use the NuttX makefile to build the system. That is almost for free
under Linux. Under Windows, you will need to set up the "Cygwin GCC" empty
makefile project in order to work with Windows (Google for "Eclipse Cygwin" -
there is a lot of help on the internet).
Native Build
------------
Here are a few tips before you start that effort:
1) Select the toolchain that you will be using in your .config file
2) Start the NuttX build at least one time from the Cygwin command line
before trying to create your project. This is necessary to create
certain auto-generated files and directories that will be needed.
3) Set up include paths: You will need include/, arch/arm/src/sam34,
arch/arm/src/common, arch/arm/src/armv7-m, and sched/.
4) All assembly files need to have the definition option -D __ASSEMBLY__
on the command line.
Startup files will probably cause you some headaches. The NuttX startup file
is arch/arm/src/sam34/sam_vectors.S. You may need to build NuttX
one time from the Cygwin command line in order to obtain the pre-built
startup object needed by an IDE.
NuttX EABI "buildroot" Toolchain
================================
A GNU GCC-based toolchain is assumed. The PATH environment variable should
be modified to point to the correct path to the Cortex-M0 GCC toolchain (if
different from the default in your PATH variable).
If you have no Cortex-M0 toolchain, one can be downloaded from the NuttX
Bitbucket download site (https://bitbucket.org/nuttx/buildroot/downloads/).
This GNU toolchain builds and executes in the Linux or Cygwin environment.
1. You must have already configured NuttX in <some-dir>/nuttx.
tools/configure.sh saml21-xplained:<sub-dir>
2. Download the latest buildroot package into <some-dir>
3. unpack the buildroot tarball. The resulting directory may
have versioning information on it like buildroot-x.y.z. If so,
rename <some-dir>/buildroot-x.y.z to <some-dir>/buildroot.
4. cd <some-dir>/buildroot
5. cp boards/cortexm0-eabi-defconfig-4.6.3 .config
6. make oldconfig
7. make
8. Make sure that the PATH variable includes the path to the newly built
binaries.
See the file boards/README.txt in the buildroot source tree. That has more
details PLUS some special instructions that you will need to follow if you are
building a Cortex-M0 toolchain for Cygwin under Windows.
LEDs and Buttons
================
LED
---
There is one yellow LED available on the SAML21 Xplained Pro board that
can be turned on and off. The LED can be activated by driving the connected
PB10 I/O line to GND.
When CONFIG_ARCH_LEDS is defined in the NuttX configuration, NuttX will
control the LED as follows:
SYMBOL Meaning 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 N/C
LED_SIGNAL In a signal handler N/C
LED_ASSERTION An assertion failed N/C
LED_PANIC The system has crashed FLASH
Thus is LED is statically on, NuttX has successfully booted and is,
apparently, running normally. If LED is flashing at approximately
2Hz, then a fatal error has been detected and the system has halted.
Button
------
SAM L21 Xplained Pro contains one mechanical button on PA02 that can be
controlled by software. When a button is pressed it will drive the I/O
line to GND. Note: There is no pull-up resistor connected to the generic
user button. Remember to enable the internal pull-up in the SAM L21 to
use the button.
QTouch Button
-------------
To be provided
Serial Consoles
===============
SERCOM0
-------
SERCOM0 is dedicated for use with SPI at the EXT1 connector
SERCOM1
-------
SERCOM1 is available as a USART on EXT2 and EXT3
PIN EXT1 EXT2 EXT3 GPIO Function
---- ---- ---- ---- ------------------
13 --- PA19 PA19 SERCOM1 / USART RX
14 --- PA18 PA18 SERCOM1 / USART TX
19 GND GND GND N/A
20 VCC VCC VCC N/A
SERCOM2
-------
SERCOM0 is dedicated for use with I2C at the EXT1, EXT2, and EXT3
connectors.
SERCOM3
-------
SERCOM3 is not available on any EXT connector but is dedicated for
use with Virtual COM (see below).
SERCOM4
-------
SERCOM1 is available as a USART on EXT1
PIN EXT1 EXT2 EXT3 GPIO Function
---- ---- ---- ---- ------------------
13 PB09 --- --- SERCOM4 / USART RX
14 PB08 --- --- SERCOM4 / USART TX
19 GND GND GND N/A
20 VCC VCC VCC N/A
SERCOM5
-------
SERCOM5 is dedicated for use with SPI at the EXT2 and EXT3 connectors
Configuration
-------------
There are options available in the NuttX configuration to select which
connector SERCOM4 is on: SAML21_XPLAINED_USART4_EXTn, where n=1, 2, or 3.
If you have a TTL to RS-232 converter then this is the most convenient
serial console to use (because you don't lose the console device each time
you lose the USB connection). It is the default in all of these
configurations. An option is to use the virtual COM port.
Virtual COM Port
----------------
The SAML21 Xplained Pro contains an Embedded Debugger (EDBG) that can be
used to program and debug the ATSAML21J18A using Serial Wire Debug (SWD).
The Embedded debugger also include a Virtual COM port interface over
SERCOM3. Virtual COM port connections:
PA22 SERCOM3 / USART TXD
PA23 SERCOM3 / USART RXD
Atmel Studio 6.1
================
NOTE: These instructions are old. The SAML21 requires Atmel Studio 6.2.
They may still prove useful to you, however.
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 AT91SAML21J18
- 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
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
==================================================
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_CORTEXM0=y
CONFIG_ARCH_CHIP - Identifies the arch/*/chip subdirectory
CONFIG_ARCH_CHIP="samd2l2"
CONFIG_ARCH_CHIP_name - For use in C code to identify the exact
chip:
CONFIG_ARCH_CHIP_SAML2X
CONFIG_ARCH_CHIP_SAML21
CONFIG_ARCH_CHIP_ATSAML21J18
CONFIG_ARCH_BOARD - Identifies the boards/ subdirectory and
hence, the board that supports the particular chip or SoC.
CONFIG_ARCH_BOARD="saml21-xplained" (for the SAML21 Xplained Pro development board)
CONFIG_ARCH_BOARD_name - For use in C code
CONFIG_ARCH_BOARD_SAML21_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=0x00010000 (64KB)
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_SAMD2L2_AC - Analog Comparator
CONFIG_SAMD2L2_ADC - Analog-to-Digital Converter
CONFIG_SAMD2L2_DAC - Digital-to-Analog Converter
CONFIG_SAMD2L2_DMAC - Analog Comparator
CONFIG_SAMD2L2_EVSYS - Event System
CONFIG_SAMD2L2_NVMCTRL - Non-Volatile Memory Controller
CONFIG_SAMD2L2_PTC - Peripheral Touch Controller
CONFIG_SAMD2L2_RTC - Real Time Counter
CONFIG_SAMD2L2_SERCOM0 - Serial Communication Interface 0
CONFIG_SAMD2L2_SERCOM1 - Serial Communication Interface 1
CONFIG_SAMD2L2_SERCOM2 - Serial Communication Interface 2
CONFIG_SAMD2L2_SERCOM3 - Serial Communication Interface 3
CONFIG_SAMD2L2_SERCOM4 - Serial Communication Interface 4
CONFIG_SAMD2L2_SERCOM5 - Serial Communication Interface 5
CONFIG_SAMD2L2_TCC0 - Timer/Counter 0 for Control
CONFIG_SAMD2L2_TCC1 - Timer/Counter 1 for Control
CONFIG_SAMD2L2_TCC2 - Timer/Counter 2 for Control
CONFIG_SAMD2L2_TC3 - Timer/Counter 3
CONFIG_SAMD2L2_TC4 - Timer/Counter 4
CONFIG_SAMD2L2_TC5 - Timer/Counter 5
CONFIG_SAMD2L2_TC6 - Timer/Counter 6
CONFIG_SAMD2L2_TC7 - Timer/Counter 6
CONFIG_SAMD2L2_USB - USB device or host
CONFIG_SAMD2L2_WDT - Watchdog Timer
Some subsystems can be configured to operate in different ways. The drivers
need to know how to configure the subsystem.
CONFIG_SAMD2L2_SERCOM0_ISI2C, CONFIG_SAMD2L2_SERCOM0_ISSPI, or CONFIG_SAMD2L2_SERCOM0_ISUSART
CONFIG_SAMD2L2_SERCOM1_ISI2C, CONFIG_SAMD2L2_SERCOM1_ISSPI, or CONFIG_SAMD2L2_SERCOM1_ISUSART
CONFIG_SAMD2L2_SERCOM2_ISI2C, CONFIG_SAMD2L2_SERCOM2_ISSPI, or CONFIG_SAMD2L2_SERCOM2_ISUSART
CONFIG_SAMD2L2_SERCOM3_ISI2C, CONFIG_SAMD2L2_SERCOM3_ISSPI, or CONFIG_SAMD2L2_SERCOM3_ISUSART
CONFIG_SAMD2L2_SERCOM4_ISI2C, CONFIG_SAMD2L2_SERCOM4_ISSPI, or CONFIG_SAMD2L2_SERCOM4_ISUSART
CONFIG_SAMD2L2_SERCOM5_ISI2C, CONFIG_SAMD2L2_SERCOM5_ISSPI, or CONFIG_SAMD2L2_SERCOM5_ISUSART
SAML21 specific device driver settings
CONFIG_USARTn_SERIAL_CONSOLE - selects the USARTn (n=0,1,2,..5) for the
console and ttys0 (default is the USART4).
CONFIG_USARTn_RXBUFSIZE - Characters are buffered as received.
This specific the size of the receive buffer
CONFIG_USARTn_TXBUFSIZE - Characters are buffered before
being sent. This specific the size of the transmit buffer
CONFIG_USARTn_BAUD - The configure BAUD of the USART. Must be
CONFIG_USARTn_BITS - The number of bits. Must be either 7 or 8.
CONFIG_USARTn_PARTIY - 0=no parity, 1=odd parity, 2=even parity
CONFIG_USARTn_2STOP - Two stop bits
Configurations
==============
Each SAML21 Xplained Pro configuration is maintained in a sub-directory and
can be selected as follow:
tools/configure.sh saml21-xplained:<subdir>
Before building, make sure that the PATH environmental 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.
NOTE: 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.
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 of on SERCOM4 which is available on EXT1 (see the section
"Serial Consoles" above). The SERCOM1 on EXT2 or EXT3 or the
virtual COM port on SERCOME could be used, instead, by
reconfiguring to use SERCOM1 or SERCOM3 instead of SERCOM4:
System Type -> SAMD/L Peripheral Support
CONFIG_SAMD2L2_SERCOM1=y : Enable one or both
CONFIG_SAMD2L2_SERCOM3=y
CONFIG_SAMD2L2_SERCOM4=n
Device Drivers -> Serial Driver Support -> Serial Console
CONFIG_USART1_SERIAL_CONSOLE=y : Select only one for the console
CONFIG_USART3_SERIAL_CONSOLE=y : Select only one for the console
CONFIG_USART4_SERIAL_CONSOLE=n
Device Drivers -> Serial Driver Support -> SERCOMn Configuration
where n=1 or 3:
CONFIG_USARTn_2STOP=0
CONFIG_USARTn_BAUD=115200
CONFIG_USARTn_BITS=8
CONFIG_USARTn_PARITY=0
CONFIG_USARTn_RXBUFSIZE=256
CONFIG_USARTn_TXBUFSIZE=256
3. Unless otherwise stated, the configurations are setup for
Cygwin under Windows:
Build Setup:
CONFIG_HOST_WINDOWS=y : Windows Host
CONFIG_WINDOWS_CYGWIN=y : Cygwin environment on windows
4. These configurations use the ARM EABI toolchain. But
that is easily reconfigured:
System Type -> Toolchain:
CONFIG_ARM_TOOLCHAIN_GNU_EABI=y
Any 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
called "GNU Toolchain Options" above.
Configuration sub-directories
-----------------------------
nsh:
This configuration directory will built the NuttShell. See NOTES above
and below:
NOTES:
1. This configuration is set up to build on Windows using the Cygwin
environment using the ARM EABI toolchain. This can be easily
changed as described above under "Configurations."
2. By default, this configuration provides a serial console on SERCOM4
at 115200 8N1 via EXT1:
PIN EXT1 GPIO Function
---- ---- ------------------
13 PB09 SERCOM4 / USART RX
14 PB08 SERCOM4 / USART TX
19 GND N/A
20 VCC N/A
If you would prefer to use the EDBG serial COM port or would prefer
to use SERCOM4 on EXT1 or EXT2, you will need to reconfigure the
SERCOM as described under "Configurations". See also the section
entitled "Serial Consoles" above.
3. NOTE: If you get a compilation error like:
libxx_new.cxx:74:40: error: 'operator new' takes type 'size_t'
('unsigned int') as first parameter [-fper
Sometimes NuttX and your toolchain will disagree on the underlying
type of size_t; sometimes it is an 'unsigned int' and sometimes it is
an 'unsigned long int'. If this error occurs, then you may need to
toggle the value of CONFIG_ARCH_SIZET_LONG.
4. WARNING: This info comes from the SAMD20 Xplained README. I have
not tried the I/O1 module on the SAML21!
If the I/O1 module is connected to the SAML21 Xplained Pro, then
support for the SD card slot can be enabled by making the following
changes to the configuration. These changes assume that the I/O1
modules is connected in EXT1. Most of the modifications necessary
to work with the I/O1 in a different connector are obvious.. except
for the selection of SERCOM SPI support:
EXT1: SPI is provided through SERCOM0
EXT2: SPI is provided through SERCOM1
EXT3: SPI is provided through SERCOM5
File Systems:
CONFIG_FS_FAT=y : Enable the FAT file system
CONFIG_FAT_LCNAMES=y : Enable upper/lower case 8.3 file names (Optional, see below)
CONFIG_FAT_LFN=y : Enable long file named (Optional, see below)
CONFIG_FAT_MAXFNAME=32 : Maximum supported file name length
There are issues related to patents that Microsoft holds on FAT long
file name technologies. See the top level NOTICE file for further
details.
System Type -> Peripherals:
CONFIG_SAMD2L2_SERCOM0=y : Use SERCOM0 if the I/O is in EXT1
CONFIG_SAMD2L2_SERCOM0_ISSPI=y : Configure SERCOM0 as an SPI master
Device Drivers
CONFIG_SPI=y : Enable SPI support
CONFIG_SPI_EXCHANGE=y : The exchange() method is supported
CONFIG_MMCSD=y : Enable MMC/SD support
CONFIG_MMCSD_NSLOTS=1 : Only one MMC/SD card slot
CONFIG_MMCSD_MULTIBLOCK_LIMIT=0 : Should not need to disable multi-block transfers
CONFIG_MMCSD_MMCSUPPORT=n : May interfere with some SD cards
CONFIG_MMCSD_HAVE_CARDDETECT=y : I/O1 module as a card detect GPIO
CONFIG_MMCSD_SPI=y : Use the SPI interface to the MMC/SD card
CONFIG_MMCSD_SPICLOCK=20000000 : This is a guess for the optimal MMC/SD frequency
CONFIG_MMCSD_SPIMODE=0 : Mode 0 is required
Board Selection -> Common Board Options
CONFIG_NSH_MMCSDSLOTNO=0 : Only one MMC/SD slot, slot 0
CONFIG_NSH_MMCSDSPIPORTNO=0 : Use port=0 -> SERCOM0 if the I/O1 is in EXT1
Board Selection -> SAML21 Xplained Pro Modules
CONFIG_SAML21_XPLAINED_IOMODULE=y : I/O1 module is connected
CONFIG_SAML21_XPLAINED_IOMODULE_EXT2=y : I/O1 modules is in EXT2
Application Configuration -> NSH Library
CONFIG_NSH_ARCHINIT=y : Board has architecture-specific initialization
NOTE: If you enable the I/O1 this configuration with SERCOM4 as the
console and with the I/O1 module in EXT1, you *must* remove USART
jumper. Otherwise, you have lookback on SERCOM4 and NSH will *not*
behave very well (since its outgoing prompts also appear as incoming
commands).
STATUS: As of 2013-6-18, this configuration appears completely
functional. Testing, however, has been very light. Example:
NuttShell (NSH) NuttX-6.34
nsh> mount -t vfat /dev/mmcsd0 /mnt/stuff
nsh> ls /mnt/stuff
/mnt/stuff:
nsh> echo "This is a test" >/mnt/stuff/atest.txt
nsh> ls /mnt/stuff
/mnt/stuff:
atest.txt
nsh> cat /mnt/stuff/atest.txt
This is a test
nsh>
5. WARNING: This info comes from the SAMD20 Xplained README. I have
not tried the OLED1 module on the SAML21!
5. If the OLED1 module is connected to the SAML21 Xplained Pro, then
support for the OLED display can be enabled by making the following
changes to the configuration. These changes assume that the I/O1
modules is connected in EXT1. Most of the modifications necessary
to work with the I/O1 in a different connector are obvious.. except
for the selection of SERCOM SPI support:
EXT1: SPI is provided through SERCOM0
EXT2: SPI is provided through SERCOM1
EXT3: SPI is provided through SERCOM5
System Type -> Peripherals:
CONFIG_SAMD2L2_SERCOM1=y : Use SERCOM1 if the I/O is in EXT2
CONFIG_SAMD2L2_SERCOM1_ISSPI=y : Configure SERCOM1 as an SPI master
Device Drivers -> SPI
CONFIG_SPI=y : Enable SPI support
CONFIG_SPI_EXCHANGE=y : The exchange() method is supported
CONFIG_SPI_CMDDATA=y : CMD/DATA support is required
Device Drivers -> LCDs
CONFIG_LCD=y : Enable LCD support
CONFIG_LCD_MAXCONTRAST=255 : Maximum contrast value
CONFIG_LCD_LANDSCAPE=y : Landscape orientation (see below*)
CONFIG_LCD_UG2832HSWEG04=y : Enable support for the OLED
CONFIG_LCD_SSD1306_SPIMODE=0 : SPI Mode 0
CONFIG_LCD_SSD1306_SPIMODE=3500000 : Pick an SPI frequency
Board Selection -> SAML21 Xplained Pro Modules
CONFIG_SAML21_XPLAINED_OLED1MODULE=y : OLED1 module is connected
CONFIG_SAML21_XPLAINED_OLED1MODULE_EXT2=y : OLED1 modules is in EXT2
The NX graphics subsystem also needs to be configured:
CONFIG_NX=y : Enable graphics support
CONFIG_NX_LCDDRIVER=y : Using an LCD driver
CONFIG_NX_NPLANES=1 : With a single color plane
CONFIG_NX_WRITEONLY=n : You can read from the LCD (see below*)
CONFIG_NX_DISABLE_2BPP=y : Disable all resolutions except 1BPP
CONFIG_NX_DISABLE_4BPP=y
CONFIG_NX_DISABLE_8BPP=y
CONFIG_NX_DISABLE_16BPP=y
CONFIG_NX_DISABLE_24BPP=y
CONFIG_NX_DISABLE_32BPP=y
CONFIG_NX_PACKEDMSFIRST=y : LSB packed first (shouldn't matter)
CONFIG_NXSTART_EXTERNINIT=y : We have board_graphics_setup()
CONFIG_NXTK_BORDERWIDTH=2 : Use a small border
CONFIG_NXTK_DEFAULT_BORDERCOLORS=y : Default border colors
CONFIG_NXFONTS_CHARBITS=7 : 7-bit fonts
CONFIG_NXFONT_SANS17X23B=y : Pick a font (any that will fit)
* The hardware is write only, but the driver maintains a frame buffer
to support read and read-write-modiry operations on the LCD.
Reading from the frame buffer is, however, untested.
Then, in order to use the OLED, you will need to build some kind of
graphics application or use one of the NuttX graphics examples.
Here, for example, is the setup for the graphic "Hello, World!"
example:
CONFIG_EXAMPLES_NXHELLO=y : Enables the example
CONFIG_EXAMPLES_NXHELLO_DEFAULT_COLORS=y : Use default colors (see below *)
CONFIG_EXAMPLES_NXHELLO_DEFAULT_FONT=y : Use the default font
CONFIG_EXAMPLES_NXHELLO_BPP=1 : One bit per pixel
CONFIG_EXAMPLES_NXHELLO_EXTERNINIT=y : Special initialization is required.
* The OLED is monochrome so the only "colors" are black and white.
The default "colors" will give you while text on a black background.
You can override the faults it you want black text on a while background.
