Unable to upload code Atmega328PB-MU

Question

I am unable to upload any code to my Atmega328PB-MU microcontroller. However I could upload the bootloader just fine. Here is my custom board to upload the bootloader. As you can see I use a adapter to program the tiny MU versions of the Atmega328PB: enter image description here

I uploaded the bootloader with these settings:

enter image description here

As I said this works and I was able to upload the bootloader. However when I try to upload any code to it it fails with this well known error message: enter image description here

This is my setup for uploading the code. I want to utalize a Arduino UNO to program the chip. I removed the microcontroller from the UNO board and wired the ATMEGA328PB-MU chip to the UNO like this:

• UNO - ATMEGA328PB-MU
• 5V -> 5V
• GND -> GND
• RX -> RX
• TX -> TX
• RESET -> RESET (with 10k pull up resistor)

Below is my setup for uploading some code: enter image description here

Here is the pinout of the Atmega328PB-MU enter image description here

Things I tried:

• switching Tx and Rx
• removing the pullup resistor
• using several other chips
• using a 16mHz Xtal (with different bootloader settings)
• USB-to-Serial-Converter

Sorry for posting another Question regarding this error but everything I found online did not help me and I think I am slowly going insane. What am I doing wrong?

Answer 1

It seems I solved the problem. Using pins 31 and 30 for Rx and Tx seemed to be the problem. Using pins 15 and 16 of the atmega328pb-mu I could finally upload my code

• Greenonline: Please mark your answer as the accepted answer.