Hi! Thanks for the help, I’ve managed to make the UART work on CC430f5137 using USCI_A0. I’ve used the implementation I’ve found in the cpu/msp430fxyz/periph/uartc. This MCU uses USCI, so I only used that kind of code. The USCI registers seemed to be laid out differently than in MSP430Fxxx, so I didn’t defined the registers, since I wanted to make this work, and I didn’t wanted to define another USCI type to make it work with the CC430. The uart works now, but when I send something to the MCU every 2-3rd time it resets, and I can’t figure it out why. Another thing is that the CC430 USCI has shared interrupt routine between rx and tx. There I did a switch for UCA0IV, where I have 0, 2,4 and default cases, where 2 is the RXIFG and 4 is the TX. I looked it up and sample codes are using this too, so this should be good, however only the 0 case catches the interrupts and I don’t know why. Here is my board init: And my uart_stdio.c: Another thing: I want to start developing the radio driver for this board, what kind of protocols/headers I will have to implement / how communications work in RIOT? Thanks! Viktor