====== OpenOCD & Raspberry Pi ======

{{:bootloader:swd-raspi_programmer_seeeduinoxiao.jpg?400|}}\\

To install the [[http://openocd.org/|open On-Chip Debugger]] on a Raspberry Pi following the manual by [[https://learn.adafruit.com/programming-microcontrollers-using-openocd-on-raspberry-pi/overview|Lady Ada]].

Install:
  $ sudo apt-get install git autoconf libtool make pkg-config libusb-1.0-0 libusb-1.0-0-dev htop
Git clone:
  $ git clone http://openocd.zylin.com/openocd
  $ cd openocd/
Configure & Install:
  $ ./bootstrap 
  $ ./configure --enable-sysfsgpio --enable-bcm2835gpio
  $ make
  $ sudo make install
Check  Interfaces:
  $ cd /usr/local/share/openocd/scripts/interface/
  $ ls
New Folder:
  $ cd ~
  $ mkdir bootloader
  $ cd bootloader
Download the Bootloader:
  $ wget https://github.com/arduino/ArduinoCore-samd/raw/master/bootloaders/zero/samd21_sam_ba.bin
  $ wget https://github.com/Seeed-Studio/ArduinoCore-samd/blob/master/bootloaders/XIAOM0/bootloader-XIAO_m0-v3.7.0-33-g90ff611-dirty.bin
  $ wget "https://github.com/arduino/ArduinoCore-samd/blob/master/bootloaders/mkrzero/samd21_sam_ba_arduino_mkrzero.bin"
Make your Config File:
  $ nano openocd.cfg
Add:
  source [find interface/raspberrypi3-native.cfg]
  transport select swd
  
  set CHIPNAME at91samd21g18
  source [find target/at91samdXX.cfg]
  
  # did not yet manage to make a working setup using srst
  #reset_config srst_only
  reset_config srst_nogate
  
  adapter srst delay 100
  adapter srst pulse_width 100
  
  #bcm2835gpio_swd_nums 25 24
  #bcm2835gpio_trst_num 7
  #bcm2835gpio_srst_num 18
  
  init
  targets
  reset halt
  
  #at91samd chip-erase
  #at91samd restore
  at91samd bootloader 0
  program samd21_sam_ba.bin verify
  #program bootloader-XIAO_m0-v3.7.0-33-g90ff611-dirty.bin verify
  #flash write_image unlock bootloader-XIAO_m0-v3.7.0-33-g90ff611-dirty.bin
  at91samd bootloader 8192
  
  reset
  shutdown
... and run it
  $ sudo openocd -f openocd.cfg
If needed change the Raspberry Pi interface file:
  $ sudo nano /usr/local/share/openocd/scripts/interface/raspberrypi2-native.cfg
  $ sudo nano /usr/local/share/openocd/scripts/interface/raspberrypi3-native.cfg
Change:
  # Each of the SWD lines need a gpio number set: swclk swdio
  # Header pin numbers: 23 22
  bcm2835gpio_swd_nums 25 24

  # If you define trst or srst, use appropriate reset_config
  # Header pin numbers: TRST - 26, SRST - 18
  bcm2835gpio_trst_num 7
  bcm2835gpio_srst_num 18

----
==== Bootloader =====

- [[https://github.com/arduino/ArduinoCore-samd|Arduino]]\\
- [[https://github.com/arduino/ArduinoCore-samd/raw/master/bootloaders/zero/samd21_sam_ba.bin|SAMD21 M0-Mini]]\\
- [[https://github.com/Seeed-Studio/ArduinoCore-samd/blob/master/bootloaders/XIAOM0/bootloader-XIAO_m0-v3.7.0-33-g90ff611-dirty.bin|Seeeduino XIAO]]\\

----
==== Pinout ====

  SWD         Raspberry Pi
  
   Reset       GPIO 18
   SWDIO       GPIO 24
   SWCLK       GPIO 25

**Arduino MKR ZERO**\\
{{:arduino:arduinomkrzero_swdpinout_02.jpg?300|}}\\

**Seeeduino XIAO**\\
{{:seeeduino:serial_wire_debug.jpg?200|}}\\

**SAMD21 M0-Mini**\\
{{:samd21:samd21-m0_mini_swdpins.jpg?200|}}\\

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==== Programming Adapter =====
These Adapter are made with Super Glue and Pogo Pins.\\

**Seeeduino XIAO Adapter**\\
{{:bootloader:seeduinoxiao_swdadapter.jpg?200|}}\\
3.3V is take from the regular pins.\\

**SAMD21 M0-Mini Adapter**\\
{{:bootloader:samd21_m0-mini_swdadapter.jpg?200|}}\\
Power and ground is  connected over the regular pins.\\

----
==== Acknowledge & Links ====

[[http://openocd.org/|open OCD]]\\
[[http://openocd.org/doc-release/pdf/openocd.pdf|OpenOCD user Guide]]\\
[[https://learn.adafruit.com/programming-microcontrollers-using-openocd-on-raspberry-pi/overview|Programming Microcontrollers using OpenOCD on a Raspberry Pi by Lady Ada]]\\
[[https://iosoft.blog/2019/01/28/raspberry-pi-openocd/|Raspberry Pi and OpenOCD by iosoft.blog]]\\


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