| .. _arduino_due: |
| |
| Board Configuration: arduino_due |
| ################################ |
| |
| Overview |
| ******** |
| |
| The arduino_due board configuration is used by Zephyr applications |
| that run on the Arduino Due board. It provides support for the Atmel |
| SAM3X8E ARM Cortex-M3 CPU and the following devices: |
| |
| * Nested Vectored Interrupt Controller (NVIC) |
| |
| * System Tick System Clock (SYSTICK) |
| |
| * Serial Port over USB (ATMEL_SAM3) |
| |
| More information about the board can be found at the `Arduino Due website`_. |
| The `Atmel SAM3X8E Datasheet`_ has the information and the datasheet about |
| the processor. |
| |
| Supported Features |
| ****************** |
| |
| The arduino_due board configuration supports the following |
| hardware features: |
| |
| +--------------+------------+----------------------+ |
| | Interface | Controller | Driver/Component | |
| +==============+============+======================+ |
| | NVIC | on-chip | nested vectored | |
| | | | interrupt controller | |
| +--------------+------------+----------------------+ |
| | SYSTICK | on-chip | system clock | |
| +--------------+------------+----------------------+ |
| | UART | on-chip | serial port | |
| +--------------+------------+----------------------+ |
| |
| Other hardware features are not currently supported by the Zephyr kernel. |
| See `Arduino Due website`_ and `Atmel SAM3X8E Datasheet`_ for a complete |
| list of Arduino Due board hardware features. |
| |
| Interrupt Controller |
| ==================== |
| |
| There are 15 fixed exceptions including exceptions 12 (debug |
| monitor) and 15 (SYSTICK) that behave more as interrupts |
| than exceptions. In addition, there can be a variable number |
| of IRQs. Exceptions 7-10 and 13 are reserved. They don't need |
| handlers. |
| |
| A Cortex-M3/4-based board uses vectored exceptions. This |
| means each exception calls a handler directly from the |
| vector table. |
| |
| Handlers are provided for exceptions 1-6, 11-12, and 14-15. |
| The table here identifies the handlers used for each exception. |
| |
| +------+------------+----------------+--------------------------+ |
| | Exc# | Name | Remarks | Used by Zephyr Kernel | |
| +======+============+================+==========================+ |
| | 1 | Reset | | system initialization | |
| +------+------------+----------------+--------------------------+ |
| | 2 | NMI | | system fatal error | |
| +------+------------+----------------+--------------------------+ |
| | 3 | Hard fault | | system fatal error | |
| +------+------------+----------------+--------------------------+ |
| | 4 | MemManage | MPU fault | system fatal error | |
| +------+------------+----------------+--------------------------+ |
| | 5 | Bus | | system fatal error | |
| +------+------------+----------------+--------------------------+ |
| | 6 | Usage | undefined | system fatal error | |
| | | fault | instruction, | | |
| | | | or switch | | |
| | | | attempt to ARM | | |
| | | | mode | | |
| +------+------------+----------------+--------------------------+ |
| | 11 | SVC | | context switch and | |
| | | | | software interrupts | |
| +------+------------+----------------+--------------------------+ |
| | 12 | Debug | | system fatal error | |
| | | monitor | | | |
| +------+------------+----------------+--------------------------+ |
| | 14 | PendSV | | context switch | |
| +------+------------+----------------+--------------------------+ |
| | 15 | SYSTICK | | system clock | |
| +------+------------+----------------+--------------------------+ |
| |
| .. note:: |
| After a reset, all exceptions have a priority of 0. Interrupts cannot run |
| at priority 0 for the interrupt locking mechanism and exception handling |
| to function properly. |
| |
| System Clock |
| ============ |
| |
| Arduino Due has two external oscillators/resonators. The slow clock is |
| 32.768 kHz, and the main clock is 12 MHz. The processor can set up PLL to drive |
| the master clock, which can be set as high as 84 MHz. |
| |
| Serial Port |
| =========== |
| |
| The Atmel SAM3X8E processor has a single UART that is used by the SAM-BA |
| bootloader. This UART has only two wires for RX/TX and does not have flow |
| control (CTS/RTS) or FIFO. The RX/TX pins are connected to the ATmega16U2, |
| which provides USB-to-TTL serial function. The Zephyr console output, by |
| default, is utilizing this controller. |
| |
| Flashing Arduino Due for Zephyr |
| =============================== |
| |
| Flashing the Zephyr kernel onto Arduino Due requires the `bossa tool`_. Note |
| that the Arduino specific version is required (branch arduino on GitHub). |
| |
| |
| The sample application hello_world is being used in this tutorial, which can |
| be found in :file:`$ZEPHYR_BASE/samples/nanokernel/apps/hello_world`. |
| |
| # To build the Zephyr kernel, enter: |
| |
| .. code-block:: console |
| |
| $ cd $ZEPHYR_BASE |
| $ make -C samples/nanokernel/apps/hello_world ARCH=arm BOARD=arduino_due |
| |
| # Connect the Arduino Due to your host computer using the programming port. |
| |
| # Press the Erase button for more than 220 ms. |
| |
| # Press the Reset button so the board will boot into the SAM-BA bootloader. |
| |
| # To flash the kernel onto Arduino Due, assuming the bossa tool already |
| exists. Using the command line version of bossa, enter: |
| |
| .. code-block:: console |
| |
| $ bossac -p <tty_device> -e -w -v -b outdir/zephyr.bin |
| |
| Where :code:`<tty_device>` is where the Arduino Due can be found. For |
| example, under Linux, :code:`<tty_device>` should be :code:`/dev/ttyACM0`. |
| |
| # Run your favorite terminal program to listen for output. For example, under |
| Linux, the terminal should be :code:`/dev/ttyACM0`. |
| |
| # Press the Reset button and you should see "Hello World!" in your terminal. |
| |
| |
| References |
| ========== |
| |
| .. _Arduino Due website: https://www.arduino.cc/en/Main/ArduinoBoardDue |
| |
| .. _Atmel SAM3X8E Datasheet: http://www.atmel.com/devices/sam3x8e.aspx |
| |
| .. _bossa tool: https://github.com/shumatech/BOSSA |