testing a microcontroller

Hi - how do you positively test if a vex microntroller is bad? -thanks

Cortex or Pic? EasyC, RobotC, or something else? Knowing that helps… but here’s a few things to try:

First, check the battery.

No, really… check the battery. Make sure it is fully charged.

Remove all dongles, sensors and PWM cables from the controller.

For the PIC-based VEX controllers, download the latest master code. Not downloading? Try a different programming cable and/or computer. You may as well try this on the Cortex, too.

Now download the “on line” code that is part of EasyC. This should give you the ability to control each motor/servo output from your computer. Plug a motor or servo into output 1. Can you control it with the slider? Try port 2. Etc.

If this isn’t working, take a look at the lights on the “front” of the controller. What do the lights show you?

Now try plugging different sensors in the the digital I/O lines and check to see what the on-line code shows you on the screen.

If the on-line code is working, then your user code should work too. I don’t have a tonne of experience with the new Cortex controllers, but I have NEVER seen an old PIC based VEX controller fail. I’m sure that someone, somewhere, has seen this, but I’ve helped teams at over a dozen events over the past five years, and can say with confidence that the old VEX controllers are tough and reliable.

(Note: Pounding on them with a hammer, swinging them about by cables, or plugging the I/O lines in to 120VAC house current may cause unexpected effects… I’ve only found them to be tough in normal wear and tear with high school students.)