Flip&Click SAM3X

This documentation discusses issues unique to NuttX configurations for the Mikroe Flip&Click SAM3X board. This board is an Arduino-Due work-alike with four Mikroe Click bus interfaces. Like the Arduino-Due, this board features the Atmel ATSAM3X8E MCU running at 84 MHz.

Thanks to John Legg for contributing the Flip&Click SAM3X board!

Buttons and LEDs

Buttons

There are no buttons on the Flip&Click SAM3X board.

LEDs

There are four LEDs on the top, blue side of the board. Only one can be controlled by software:

  • LED L - PB27 (PWM13)

There are also four LEDs on the back, white side of the board:

  • LED A - PC6

  • LED B - PC5

  • LED C - PC7

  • LED D - PC8

A high output value illuminates the LEDs.

These LEDs are available to the application and are all available to the application 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

L

A

B

C

D

LED_STARTED

NuttX has been started

OFF

ON

OFF

OFF

OFF

LED_HEAPALLOCATE

Heap has been allocated

OFF

OFF

ON

OFF

OFF

LED_IRQSENABLED

Interrupts enabled

OFF

OFF

OFF

ON

OFF

LED_STACKCREATED

Idle stack created

OFF

OFF

OFF

OFF

ON

LED_INIRQ

In an interrupt

GLO

N/C

N/C

N/C

N/C

LED_SIGNAL

In a signal handler

GLO

N/C

N/C

N/C

N/C

LED_ASSERTION

An assertion failed

GLO

N/C

N/C

N/C

N/C

LED_PANIC

The system has crashed

2Hz

N/C

N/C

N/C

N/C

LED_IDLE

MCU is is sleep mode

N/A

N/A

N/A

N/A

N/A

Thus if LED L is glowing faintly and all other LEDs are off (except LED D which was left on but is no longer controlled by NuttX and so may be in any state), NuttX has successfully booted and is, apparently, running normally and taking interrupts. If any of LEDs A-D are statically set, then NuttX failed to boot and the LED indicates the initialization phase where the failure occurred. If LED L is flashing at approximately 2Hz, then a fatal error has been detected and the system has halted.

Note

After booting, LEDs A-D are no longer used by the system and may be controlled the application.

Serial Consoles

The SAM3X has a UART and 4 USARTS. The Programming port uses a USB-to- serial chip connected to the first of the MCU (RX0 and TX0 on PA8 and PA9, respectively). The output from that port is visible using the Arduino tool.

Note

My experience so far: I get serial output on the virtual COM port via the UART, but I receive no serial input for keyboard data entered in the PC serial terminal. I have not investigated this problem. It may be something as simple as the Rx pin configuration. Instead, I just switched to USART0.

Other convenient U[S]ARTs that may be used as the Serial console include:

  1. An Arduino Serial Shield. The RX and TX pins are available on the Arduino connector D0 and D1 pins, respectively. These are connected to USART0, RXD0 and TXD0 which are PA10 and PA11, respectively.

  2. Mikroe Click Serial Shield. There are four Click bus connectors with serial ports available as follows:

    • Click A: USART0 RXD0 and TXD0 which are, again, PA10 and PA11.

    • Click B: USART1 RXD1 and TXD1 which are PA12 and PA13, respectively.

    • Click C: USART3 RXD3 and TXD3 which are PD5 and PD4, respectively.

    • Click D: USART3 RXD3 and TXD3 which are, again, PD5 and PD4.

Other serial ports are probably available on the Arduino connector. I will leave that as an exercise for the interested reader.

The outputs from these pins is 3.3V. You will need to connect RS232 transceiver to get the signals to RS232 levels (or connect to the USB virtual COM port in the case of UART0).

Any of UART and USART0-3 may be used as a serial console. UART0 would be the preferred default console setting. However, due to the communication problems mentioned above, USART0 is used as the default serial console in all configurations. But that is easily changed by modifying the configuration as described under “Configurations” below.

SPI

SPI0 is available on the Arduino compatible SPI connector (but no SPI is available on pins D10-D13 of the main Arduino Shield connectors where you might expect them). The SPI connector is configured as follows:

Pin

Board Signal

SAM3X

Pin

Board Signal

SAM3X

1

SPI0_MISO

PA25

2

VCC-5V

N/A

3

SPI0_SCK

PA27

4

SPI0_MOSI

PA26

5

MRST

NRSTB

6

GND

N/A

SPI0 is also available on each of the mikroBUS Click connectors (in addition to 5V and GND). The connectivity differs only in the chip select pin:

MikroBUS A

Pin

Board Signal

SAM3X

CS

SPI0_CS0

PA28

SCK

SPI0_SCK

PA27

MISO

SPI0_MISO

PA25

MOSI

SPI0_MOSI

PA26

MikroBUS B:

Pin

Board Signal

SAM3X

CS

PA29

PA29

SCK

SPI0_SCK

PA27

MISO

SPI0_MISO

PA25

MOSI

SPI0_MOSI

PA26

MikroBUS C

Pin

Board Signal

SAM3X

CS

SPI0_CS2

PB21

SCK

SPI0_SCK

PA27

MISO

SPI0_MISO

PA25

MOSI

SPI0_MOSI

PA26

MikroBUS D

Pin

Board Signal

SAM3X

CS

SPI0_CS3

PB23

SCK

SPI0_SCK

PA27

MISO

SPI0_MISO

PA25

MOSI

SPI0_MOSI

PA26

I2C

I2C0 is available on pins D16-D17 of the Arduino Shield connectors where you would expect them. The SPI connector is configured as follows:

Pin

Label

J1

Board Signal

SAM3X

D16

SCL1

8

I2C0_SCL

PA17

D17

SDA1

7

I2C0_SDA

PA18

I2C0 and I2C1 are also available on the mikroBUS Click connectors (in addition to 5V and GND). The connectors A and B share I2C0 with the Arduino shield connector. Connectors C and D both connect to I2C1:

MikroBUS A

Pin

Board Signal

SAM3X

SCL

I2C0_SCL

PA17

SDA

I2C0_SDA

PA1

MikroBUS B

Pin

Board Signal

SAM3X

SCL

I2C0_SCL

PA17

SDA

I2C0_SDA

PA18

MikroBUS C

Pin

Board Signal

SAM3X

SCL

I2C1_SCL

PB13

SDA

I2C1_SDA

PB12

MikroBUS D

Pin

Board Signal

SAM3X

SCL

I2C1_SCL

PB13

SDA

I2C1_SDA

PB12

SSD1306 OLED

Hardware

The HiletGo is a 128x64 OLED that can be driven either via SPI or I2C (SPI is the default and is what is used here). I have mounted the OLED on a proto click board. The OLED is connected as follows:

OLED

ALIAS

DESCRIPTION

PROTO CLICK

GND

Ground

GND

VCC

Power Supply

5V (3-5V)

D0

SCL,CLK,SCK

Clock

SCK

D1

SDA,MOSI

Data

MOSI,SDI

RES

RST,RESET

Reset

RST (GPIO OUTPUT)

DC

AO

Data/Command

INT (GPIO OUTPUT)

CS

Chip Select

CS (GPIO OUTPUT)

Note

This is a write-only display (MOSI only)!

Loading Code

Note

This text was mostly copied from the Arduino Due README.txt. I believe, however, that there have been significant changes to the tool environment such that Bossac may no longer be usable. I don’t know that for certain and perhaps someone with more knowledge of the tools than I could make this work. See STATUS below for the current issues that I see.

Installing the Arduino USB Driver under Windows

  1. Download the Windows version of the Arduino software, not the 1.0.x release but the latest (1.5.x or later) that supports the Arduino Due. When the download finishes, unzip the downloaded file.

    In the current 1.8.x release, the Arduino Due support is not included in the base package but can be added by selecting the “Boards Manager” from the “Tools” menu.

  2. Connect the Flip&Click to your computer with a USB cable via the Programming port.

  3. The Windows driver installation should fail.

  4. Open the Device Manager

  5. Look for the listing named “Ports (COM & LPT)”. You should see an open port named “Arduino Due Prog. Port”. Right click and select “Update driver”.

  6. Select the “Browse my computer for Driver software” option.

  7. Right click on the “Arduino Due Prog. Port” and choose “Update Driver Software”.

  8. Navigate to the folder with the Arduino IDE you downloaded and unzipped earlier. Locate and select the “Drivers” folder in the main Arduino folder (not the “FTDI USB Drivers” sub-directory).

Loading NuttX to the Flip&Click Using Bossa

Arduino uses BOSSA under the hood to load code and you can use BOSSA outside of Arduino.

Where do you get it?

Generic BOSSA installation files are available here: https://github.com/shumatech/BOSSA (formerly at http://sourceforge.net/projects/b-o-s-s-a/?source=dlp)

Pre-built binaries are available: https://github.com/shumatech/BOSSA/releases

The original Arduino DUE used a patched version of BOSSA available as source code here: https://github.com/shumatech/BOSSA/tree/arduino But that has most likely been incorporated into the main github repository.

But, fortunately, since you already installed Arduino, you already have BOSSA installed. In my installation, it is here:

$ C:\Program Files (x86)\Arduino\arduino-1.5.2\hardware\tools\bossac.exe

General Procedure

  1. Erase the FLASH and put the Flip&Click in bootloader mode

  2. Write the file to FLASH

  3. Configure to boot from FLASH

  4. Reset the Flip&Click

Erase FLASH and Put the Flip&Click in Bootloader Mode

This is accomplished by simply configuring the programming port in 1200 baud and sending something on the programming port. Here is some sample output from a Windows CMD.exe shell. NOTE that my Arduino programming port shows up as COM7. It may be different on your system.

To enter boot mode, set the baud to 1200 and send anything to the programming port:

$ C:\Program Files (x86)\Arduino\arduino-1.5.2\hardware\tools>mode com26:1200,n,8,1

Status for device COM7:
------------------------
    Baud:            1200
    Parity:          None
    Data Bits:       8
    Stop Bits:       1
    Timeout:         ON
    XON/XOFF:        OFF
    CTS handshaking: OFF
    DSR handshaking: OFF
    DSR sensitivity: OFF
    DTR circuit:     ON
    RTS circuit:     ON

$ C:\Program Files (x86)\Arduino\arduino-1.5.2\hardware\tools>bossac.exe --port=COM7 --usb-port=false -i
    Device       : ATSAM3X8
    Version      : v1.1 Dec 15 2010 19:25:04
    Address      : 0x80000
    Pages        : 2048
    Page Size    : 256 bytes
    Total Size   : 512KB
    Planes       : 2
    Lock Regions : 32
    Locked       : none
    Security     : false
    Boot Flash   : false

Writing FLASH and Setting FLASH Boot Mode

In a Cygwin BaSH shell:

$ export PATH="/cygdrive/c/Program Files (x86)/Arduino/arduino-1.5.2/hardware/tools":$PATH

  Erasing, writing, and verifying FLASH with bossac:

    $ bossac.exe --port=COM7 --usb-port=false -e -w -v -b nuttx.bin -R
    Erase flash
    Write 86588 bytes to flash
    [==============================] 100% (339/339 pages)
    Verify 86588 bytes of flash
    [==============================] 100% (339/339 pages)
    Verify successful
    Set boot flash true
    CPU reset.

Some things that can go wrong:

$ bossac.exe --port=COM7 --usb-port=false -e -w -v -b nuttx.bin -R
No device found on COM7

This error means that there is code running on the Flip&Click already so the bootloader cannot connect. Press reset and try again

$ bossac.exe --port=COM7 --usb-port=false -e -w -v -b nuttx.bin -R
No device found on COM7

Still No connection because the board does not jump to bootloader after reset. Set the baud to 1200 and send something then try again

$ bossac.exe --port=COM7 --usb-port=false -e -w -v -b nuttx.bin -R
Erase flash
Write 86588 bytes to flash
[==============================] 100% (339/339 pages)
Verify 86588 bytes of flash
[==============================] 100% (339/339 pages)
Verify successful
Set boot flash true
CPU reset.

Other useful bossac operations.

  1. Write code to FLASH don’t change boot mode and don’t reset. This lets you examine the FLASH contents that you just loaded while the bootloader is still active.

    $ bossac.exe --port=COM7 --usb-port=false -e -w -v --boot=0 nuttx.bin
Write 64628 bytes to flash
[==============================] 100% (253/253 pages)
Verify 64628 bytes of flash
[==============================] 100% (253/253 pages)
Verify successful

  2. Verify the FLASH contents (the bootloader must be running)

    $ bossac.exe --port=COM7 --usb-port=false -v nuttx.bin
Verify 64628 bytes of flash
[==============================] 100% (253/253 pages)
Verify successful

  3. Read from FLASH to a file (the bootloader must be running):

    $ bossac.exe --port=COM7 --usb-port=false --read=4096 nuttx.dump
Read 4096 bytes from flash
[==============================] 100% (16/16 pages)

  4. Change to boot from FLASH

    $ bossac.exe --port=COM7 --usb-port=false --boot=1
Set boot flash true

Warning

At present this procedure does not work. I do the following:

  1. Open TeraTerm, select COM7 at 1200 baud, type a few ENTERs, and close teraterm.

  2. Execute the following command which claims to have successfully written to FLASH.

    $ bossac.exe --info --debug --port COM7 --usb-port=0 --erase --write --verify -b nuttx.bin -R

    But the code does not boot. There is no indication of life.

  3. Repeat 1. then

    $ bossac.exe --info --debug --port COM7 --usb-port=0 --verify -b nuttx.bin

    And it says that the content of the FLASH is not good.

Uploading NuttX to the Flip&Click Using JTAG

The JTAG/SWD signals are brought out to a 10-pin header JTAG connector:

PIN

SIGNAL

JTAG STANDARD

NOTES

1

VCC-3.3V

VTref

2

JTAG_TMS

SWDIO/TMS

SAM3X pin 31, Pulled up on board

3

GND

GND

4

JTAG_TCK

SWDCLK/TCK

SAM3X pin 28, Pulled up on board

5

GND

GND

6

JTAG_TDO

SWO/EXta/TRACECTL

SAM3X pin 30, Pulled up on board

7

N/C

Key

8

JTAG_TDI

NC/EXTb/TDI

SAM3X pin 29, Pulled up on board

9

GND

GNDDetect

10

MRST

nReset

Note

The 10-pin JTAG connector is not populated on the Flip&Click SAM3X. This is the part number for the SMD connector recommended by ARM.com: Samtec FTSH-105-01-L-DV-K. For example: https://www.digikey.com/product-detail/en/samtec-inc/FTSH-105-01-L-DV-K/SAM8799-ND/1875039

You should be able to use a 10- to 20-pin adapter to connect a SAM-ICE or J-Link debugger to the Flip&Click SAM3X. I have this Olimex adapter: https://www.olimex.com/Products/ARM/JTAG/ARM-JTAG-20-10/. I have been loading code and debugging with no problems using JTAG.

Flip&Click SAM3X-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_CORTEXM3=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_SAM3X

    • CONFIG_ARCH_CHIP_ATSAM3X8E

  • CONFIG_ARCH_BOARD: Identifies the boards/ subdirectory and hence, the board that supports the particular chip or SoC.

    • CONFIG_ARCH_BOARD=flipnclick-sam3x (for the Flip&Click SAM3X development board)

  • CONFIG_ARCH_BOARD_name: For use in C code

    • CONFIG_ARCH_BOARD_FLIPNCLICK_SAM3X=y

  • CONFIG_ARCH_LOOPSPERMSEC: Must be calibrated for correct operation of delay loops

  • CONFIG_RAM_SIZE: Describes the installed DRAM (SRAM in this case):

    • CONFIG_RAM_SIZE=65536 (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

Individual subsystems can be enabled:

  • CONFIG_SAM34_ADC12B: 12-bit Analog To Digital Converter

  • CONFIG_SAM34_CAN0: CAN Controller 0

  • CONFIG_SAM34_CAN1: CAN Controller 1

  • CONFIG_SAM34_DACC: Digital To Analog Converter

  • CONFIG_SAM34_DMAC0: DMA Controller

  • CONFIG_SAM34_EMAC: Ethernet MAC

  • CONFIG_SAM34_HSMCI: High Speed Multimedia Card Interface

  • CONFIG_SAM34_PWM: Pulse Width Modulation

  • CONFIG_SAM34_RTC: Real Time Clock

  • CONFIG_SAM34_RTT: Real Time Timer

  • CONFIG_SAM34_SDRAMC: SDRAM Controller

  • CONFIG_SAM34_SMC: Static Memory Controller

  • CONFIG_SAM34_SPI0: Serial Peripheral Interface 0

  • CONFIG_SAM34_SPI1: Serial Peripheral Interface 1

  • 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_TC6: Timer Counter 6

  • CONFIG_SAM34_TC7: Timer Counter 7

  • CONFIG_SAM34_TC8: Timer Counter 8

  • CONFIG_SAM34_TRNG: True Random Number Generator

  • CONFIG_SAM34_TWIM/S0: Two-Wire Interface 0 (master/slave)

  • CONFIG_SAM34_TWIM/S1: Two-Wire Interface 1 (master/slave)

  • CONFIG_SAM34_UART0: UART 0

  • CONFIG_SAM34_UOTGHS: USB OTG High Speed

  • CONFIG_SAM34_USART0: USART 0

  • CONFIG_SAM34_USART1: USART 1

  • CONFIG_SAM34_USART2: USART 2

  • CONFIG_SAM34_USART3: USART 3

  • CONFIG_SAM34_WDT: Watchdog Timer

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_SAM34_GPIOD_IRQ

  • CONFIG_SAM34_GPIOE_IRQ

  • CONFIG_SAM34_GPIOF_IRQ

Configurations

Each Flip&Click SAM3X configuration is maintained in a sub-directory and can be selected as follows:

$ tools/configure.sh [OPTIONS] flipnclick-sam3x:<subdir>

Where typical options are -l to configure to build on Linux or -c to configure for Cygwin under Linux. tools/configure.sh -h will show you all of the options.

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 one of the following:

These configurations use the mconf-based configuration tool. To change any of these configurations using that tool, you should:

  1. Build and install the kconfig-mconf tool. See nuttx/README.txt see additional README.txt files in the NuttX tools repository.

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

Unless stated otherwise, all configurations generate console output on USART0 which is available either on the Arduion Shield connector or on mikroBUS A as described above in the section entitled “Serial Consoles”.

Unless otherwise stated, the configurations are setup for Cygwin under Windows:

Build Setup:

  • CONFIG_HOST_WINDOWS=y: Microsoft Windows

  • CONFIG_WINDIWS_CYGWIN=y: Cygwin under Windows

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://developer.arm.com/open-source/gnu-toolchain/gnu-rm

That toolchain selection can easily be reconfigured using make menuconfig. Here are the relevant current settings:

System Type -> Toolchain:

  • CONFIG_ARM_TOOLCHAIN_GNU_EABI=y: GNU ARM EABI toolchain for Windows

nsh

This configuration directory will build the NuttShell.

NSH built-in applications are supported. However, there are no built-in applications built with the default configuration.

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

nxlines

This is an NSH configuration that supports the NX graphics example at apps/examples/nxlines as a built-in application.

This configuration derives from the nsh configuration. All of the notes there apply here as well.

The default configuration assumes there is the custom HiletGo OLED in the mikroBUS B slot (and a Mikroe RS-232 Click card in the mikroBUS A slot). That is easily changed by reconfiguring, however. See the section entitled “HiletGo OLED” for information about this custom click card.

Warning

2018-02-11: No complaints from the software, but nothing appears on the OLED. There is, most likely, an error in my custom HiletGo Click. Damn!