Burning Arduino bootloader on MCU SAMD21G

samd21g arduino bootloader swd

A custom crystalless PCB with SAMD21G and PWD pins are required to upload the Arduino bootloader in the bare micro-controller.

Create the bootloader file

Clone ArduinoCore-samd
Go to folder /bootloaders/zero

(Option) Edit Makefile line 66 for crystalless board

 CFLAGS_EXTRA=-D__SAMD21G18A__ -DBOARD_ID_$(BOARD_ID) -D$(SAM_BA_INTERFACES) -DCRYSTALLESS

(Optional) Edit board_definitions_arduino_zero.h line 26 to change product name
```
 #define STRING_PRODUCT "Pine"
```
(Optional) Edit sam_ba_usb.c line 156 to change manufacturer name
```
 #define STRING_MANUFACTURER "Hutscape"
```
Run make
Ensure files bootloaders/zero/samd21_sam_ba.bin and bootloaders/zero/samd21_sam_ba.hex are created

Burn the bootloader

Download and open SEGGER J-Flash Lite
Connect the J-Link SEGGER with PWD pins to the PCB
Choose the created bootloader data file samd21_sam_ba.bin
Click Program Device
Disconnect J-Link SEGGER and connect the PCB to the laptop
Double press the reset button to bring it into the bootloader mode
Query ls -al /dev/cu.usbmodem* to ensure the port is detected

Query arduino-cli board list | grep arduino to ensure the board is detected

  /dev/cu.usbmodem14101           Serial Port (USB) Arduino Zero (Native USB Port) arduino:samd:arduino_zero_native arduino:samd

Flash the blinky LED program with crystalless option

Prototype

A photo of the actual setup.

Burning Arduino bootloader on MCU SAMD21G prototype

Schematic

Wire up the hardware accordingly

Burning Arduino bootloader on MCU SAMD21G schematic

References