Hello TI Forum,
I have an MSP-FET Flash Emulation Tool that I use to program MSP430 micrcontrollers on custom, externally powered boards. Oftentimes I will leave the tool plugged in to my computer, connect the 14-pin idc connector to the custom PCB, and then turn on the external power to the board. However, I've noticed that if the MSP-FET is plugged in to my computer and the unpowered external board, the red led illuminates by itself (no green LED). I've also noticed there is voltage on the RST pin (and some other pins) that cycles up to 1.8V then goes back to 0V, repeating.
Once I externally power my custom pcb, the red led turns off, the green led turns on, and I can program it no issue. But I'm a little concerned with the behavior I'm seeing. I couldn't find any instructions that say "you must plug in the MSP-FET after turning on external power", so I've been assuming it doesn't matter if the FET tool is plugged in before applying external power. But, since I have the pin connections set up for programming an externally powered device, I'm surprised to see the tool injecting power into the target board. Is this expected behavior? Is it possible I have a faulty MSP-FET?
Thanks in advance for any assistance!