HCS12 power supply overheating, unable to connect using COM port from Codewarrior debug

[rpatricio]

Hello,

Out of nowhere I was unable to connect to my HCS12 board using COM ports and Codewarrior debug. After trying to figure out what was wrong I noticed that when plugged the power into the board the LM2940CS chip on the power supply(I think) would over heat extremely  as well as the MC9S12DG128 on the debug module. I was wondering if this may possibly have something to do with the problem. The VCC on the bread board part still outputs ~5V but the LEDs on the board don't turn on when I plug the board in. Using codewarrior I can't connect to the COM port on the debug and the registers just turn to "BEEF".

I am a student in 2nd year engineering tech at BCIT and this has forced me to drop out of a fast paced course half way in because I cannot fix the problem and I can't afford to buy a new board right now. I apologize for not being more descriptive as this is the first course I have used microcontrollers and in a way I am new to the use of them.

[RadekS]

According you description, it seems that you have some short on your board. It is possible that short is caused by some damaging of MCU. Unfortunately hardware debugging isn’t simplest in this case. As first you have to disconnect all possible circuits from MCU. If this helps, you can try connecting circuit by circuit to MCU and test where issue could be. If disconnecting all possible circuits from MCU didn’t help, MCU is probably damaged and you have to replace this part or potentially use board warranty.

LM2940 contains protection circuits therefore I suppose that when you remove short, LDO will work correctly.