How to break your JimStim

[jsmcortina]

By carelessness I broke the CPU on one of my JimStims today. I was connecting up a 12v supply using a croc clip - with the power on - and inadvertently touched a different pin with the clip. This pin turned out to be the 3.3v power supply rail on the BDM header.

12v is well outside the design specs on the CPU and it broke. Now the CPU gets hot and the voltage regulator gets hotter.

With correct connection the CPU will never get 12v. I've been using my prototype for something like a year now and this is the first problem I've had.

Motto - take care when wiring anything electrical and do it with the power off.

James

[Peter Florance]

By carelessness I broke the CPU on one of my JimStims today. I was connecting up a 12v supply using a croc clip - with the power on - and inadvertently touched a different pin with the clip. This pin turned out to be the 3.3v power supply rail on the BDM header.

12v is well outside the design specs on the CPU and it broke. Now the CPU gets hot and the voltage regulator gets hotter.

With correct connection the CPU will never get 12v. I've been using my prototype for something like a year now and this is the first problem I've had.

Motto - take care when wiring anything electrical and do it with the power off.

James

James,
I just wanted to verify your findings and now I can say you're right.
I also shorted something underneath in a moment of carelessness and have a working, but very hot processor.

I have some spare processors that I purchased to make the SD logger card. I have a BDM cable.
But... I recall there was some issue with V1.0 board's BDM header. Can anyone verify this?

Also does anyone have current firmware image?

thanks!

[jsmcortina]

I'm afraid the firmware isn't available, so you'll need to get a fresh CPU.

James

[Peter Florance]

I'm afraid the firmware isn't available, so you'll need to get a fresh CPU.

James

Thanks, I can order from JBperf

[LT401Vette]

Now the CPU gets hot and the voltage regulator gets hotter.

Bulls eye....

I'll try a new cpu

[Reverant]

This appears to be a common issue on several Motorola microcontrollers. It has happened to me too, with many different microcontrollers (AVRs too be exact) and they get very hot during operation, but if you trace the fault and fix it (usually electrical shorts on prototype boards) then the CPU is still fine: It no longer gets hot and even the affected processor pin remains fully functional. Not so for the Motorolas.

Dimitris