Dead processor?

[dominicbeesley]

Hello all,

I've just started building my v3.00 with MS-II up and got as far as step 54 - testing the inputs.

I'd already managed to Flash the chip and tested out a few functions by hookin things up to a loom. I'm powering the thing over a 12' loom from a bench power supply running at 12V.

I'd attached an audio signal generator to the ignition input and could get the rev counter in megatune to go up and down at 1/4 the input frequency. The thing is set up for a VR input and this all seemed to work as I'd expect.

Then I decided to change the ignition settings - to those for my Mazda MX-6. Cycled the power and things went strange.
All the dials started to flash in megatune and battery was going high/low about once a second. I checked power and output from the voltage regulator and all was well. Power cycling did nothing

Next I tried re-flashing and this seemed to fix things for a few seconds then the same symptoms started.

Next the unit died completely and couldn't get any life.

I tried reflashing and after several power cycles and time-outs it reflashed, worked briefly then died.

Now I can't even reflash.

I've checked all the power points on the daughter board and these are all at 4.94V and look clean on the scope.
I've tried removing the chip and doing a loop-back test and it seems fine.

Is my processor borked?

Any help would be good - it seems daft to fall at the start like this!

Dom

[Matt Cramer]

I would first check for a short on the PCB - the processor won't work if it's getting the wrong voltages. To check for a short in the Megasquirt PCB, 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.

[dominicbeesley]

Thanks to Matt for his quick help....I tested all the voltages and all was well. Then I tried on a different laptop and now it is working again so maybe there's a problem with Windows 2008 server?!

I'm going to leave it running for a few hours to see if its a heat problem but I think it is ok, it doesn't feel like its getting hot and is not drawing a lot of current.

Cheers

Dom

[toyota 5VZ]

hellow from chile
sorry about mi inglish
please help me
i m make same test after leave 6 monds mi projet stand bye
i test com port seting and now i m testing the voltage same your indication
al is ok but mi power source is a battery car i have 12,8volt

s12 i dont know were is it
s12c =12,06v
Q9 = 12,8V
Q12= 12,8
D3 = 12,8
U5 = 12,06
D9 = 12,06

I hope find the problem

thanks a lot

[DonTZ125]

No apologies needed - you probably speak better English than I speak Spanish!

If you are using a car battery for your 12v, you must use a fuse (fusible) - a short circuit (cortocircuito?) will allow enough current to destroy your board!

Read Matt's post again - you are checking for 12v and 5v. There are components that have 5v on one end, 12v on the other. 'Left' (izquierda) and 'right' (derecha) is when the heat sink is at the top, and the big DB37 connector is on your right.

12v:
S12
S12c
Q9, center leg
Q12, center leg
D3, left (izquierda) leg
U5, left leg
D9, left leg

5v:
S5
+5v holes in the proto area
D9, right (derecha) leg
U5, right leg
D19, left leg
Pins 1, 20, 31 on the CPU