I am using two mcus, they are MSPM0G3507 from TI, and STM32G474 from ST and I want the stm32 mcu to command the msp mcu via uart. I am now transmitting a byte from stm32 using interrupt, and if that byte is correct the msp mcu would send a byte back to stm32 mcu using DMA. The problem is the transmission from stm32 to msp is ok, but the transmission from msp to stm32 not working, the uart Rx handler function in the stm32 mcu was not called, the stm32 mcu received nothing (using a oscilloscope I did not see any logic signal). A weird thing happens that when I connect the Tx pin and GND pin of the msp mcu to a Jlink-OB V2 in parallel with stm32 mcu, and only then the transmission from msp to stm32 started working, the byte the stm32 mcu received was correct and I can see the logic signals on the oscilloscope also the byte that my PC received using that Jlink was correct too. When I connect Jlink to msp but not connect that Jlink to my PC the transmision from msp to stm32 works just fine. Does anyone has any idea about this? Please let me know.
For the stm32 mcu: Rx using DMA. Tx using interrupt. for the msp mcu: Rx and Tx using DMA. mu configs here myconfig
I tried the uart example code (uart transmission using DMA) from TI for the transmission from msp to stm32 but it is still not working, it worked only when a Jlink-OB V2 connected in parallel like I said.