megasquirt died, steps to test?

[stoker100]

i added 2 shield wires to MS ground, went to start the car up and it wouldnt start and now i cannot communicate with the unit.

Ive tried the serial loopback test and can communicate up to the microprocessor (when shorting pins 12-13 i can communicate with MS in hyperterminal).

I have then gone to reload the firmware and recieved a message:
download failed: expected responseboot>",
but received this "".

there is 5V to all the correct pins on the micro.

any suggestions? thanks.

[mac1]

I hate when this crap happens, are you still hooked up to the car when reflashing the firmware or using a stim with a 9v battery?

[stoker100]

yep, im not enjoying this time either. Im using a 12V 7AH battery, battery voltage is good. im pretty sure the microprocessor is fried. Im 100% sure the 2 wires I connected to are shields so i have no idea how its fried my processor but now i have to order one and play the waiting game. It especially sucks because I have to drop the car off next week to get my SC pipes made up and i know i wont have it running anytime soon.

I have ordered another micro hopefully it comes in next week but i wont hold my breath, there is also very little parts support down under.

[Spec]

Ouch. Sorry dude. Any chance you can find someone local to either fix the unit or put together another one?

[klze662]

try just unplugging the processor from the socket and then testing the pins on the processor socket. The should reset any values or faults it may have, leaving it plugged in it may just draw enough power from the capacitors to keep errors in memory. also next don't shield it yet a small break in the wire can cause a short. Then last try cleaning the whole board with isopropyl rubbing alcohol and test again.

[Matt Cramer]

To check for a short in the Megasquirt PCB (assuming this is a V3.0 here), power up the Megasquirt on a Stimulator or on the car and check the following points for voltage with a multimeter.

You should find the same voltage as the battery voltage on the following points: S12, S12C, the center legs of Q9 and Q12, the left (non-banded) end of D3, the left leg of U5, and the left (banded) end of D9.

You should have 5 volts at the following points: S5, the two +5V holes in the proto area, the right (non-banded) end of D9, the right leg of U5, the left (banded) end of D19, and pins 1, 20, and 31 of the CPU.

Let me know where you find the correct voltages, and where you find the wrong ones. If you get all correct voltages, I'd first try removing the processor and jumpering pins 12 and 13, and doing a serial loopback test. If it passes that, replace the CPU; if that fails, replace U6.