[Dude] How to set SAMD21G18 to running at 1,8v?

Hi, i am working with SAMD21G18 and a custom board based on sparkfun design.

Actually i want run at 1,8v instead of 3,3v. Now, the hw works well witn 3,3v but when i use 1,8v don´t work.

I have disabled the fuse BOD33 using Atmel Studio, but the microcontroller don´t work. How i could change the fuses in platformio?

Do i need set any other option to work at 1,8v?

Thanks for your time.

PD: My platformio.ini file is:

;PlatformIO Project Configuration File
; Build options: build flags, source filter
; Upload options: custom upload port, speed and extra flags
; Library options: dependencies, extra library storages
; Advanced options: extra scripting
; Please visit documentation for the other options and examples
; Redirecting...

platform = atmelsam
board = samd21g18a
framework = arduino
build_flags = -D CRYSTALLESS
board_build.variant = SparkFun_SAMD_Mini

; SWD interface
upload_protocol = jlink
debug_tool = jlink

So even when you program the correct fuses via Atmel Studio to enable 1.8V operation, the microcontroller / firmware still doesn’t work? But then how can it be solved with PIO by programming the same fuses o_o?

The JLink upload option doesn’t change the fuses of the SAMD21G18 (or, any other devices, it never toches them for the Atmel SAM platform), see here. It just tells JLink.exe to write the firmware into it.

I suggest you change the fuses once in Atmel Studio and flash a working firmware from there or identify the problem why it won’t run at 1.8V. If PIO is supposed to burn / check the fuses, this is currently not implemented for atmel-sam as far as I can tell. You can create an issue there (Issues · platformio/platform-atmelsam · GitHub) or use advanced scripting to write an extenion script which checks / burns the right fuses using the JLink tool.


I only change the fuse BOD33 using Atmel studio and i upload again the code. If i set VCC to 1.8v or 3.3v , the firm can be uploaded using jlink.

If i set the vcc, the hw works fine and execute the code. A simple code that put one pin in hihg/low and send a message by UART interface. When i set VCC=1.8v, the hw not work.

I have solder the ucontroller and passive components that they are neccessary to run.

In datahseet i found that NVM Wait States should be modified to run at 48mhz and VCC less than 2.7v [NVM characteristics - Table 37-42. Maximum Operating Frequency]. I tried to change clock speed to 28mhz and when i set vcc to 1.8v not work but with 3.3v works well.