We are having a problem where out robot's NXT brick keeps freezing up mid-telop . We checked our code and there does not seem to be a place where the the brick would have trouble executing the code. We tried to switch bricks and had the same issue.

The code is attached, any help would be appreciated.

Thanks

Are you using a separate power source for your Samantha module? I've heard that sudden power surges due to motor activity can cause a brown-out and reset of the module.

- Xander

the Samantha is powered off the 12 volt battery where the brick is powered of a NXT rechargeable battery. The Samantha lights are still on even after the brick freezes.

Are you certain the NXT brick is freezing? Or is the NXT program still running and you are you just losing joystick control of your robot? What do you do to unfreeze the NXT? Can you still exit the program with the grey button once the problem appears?

We ran into some major issues early in the season where a momentary loss of connection in the 12VDC feed to Samantha caused the wifi connection to drop, which in turn caused a loss of control to the robot. It turned out to be a damaged pin in the battery connector. Jiggling the wires (or driving the robot) caused the power to drop out momentarily from time to time. We have now replaced all the battery connectors with PowerPole and the problem went away.

it is defiantly the brick even when we turn off the robot power the screen remains frozen and we have to take out the batteries or reset to get it working again. We attempted switching bricks to see if it was the brick but the same thing happened on the second brick (not all the time just some times)

I vaguely recall having issues when writing an INT variable to a Servo, but I don't think it was crashing the NXT it was more of an overflow issue causing the servo to go to unexpected positions. Anyhow, you might want to change the line servotarget[arm] = (short) input; Nothing else in your code looks like it should cause a problem. Are you definitely using RobotC V3.05 with the corresponding NXT firmware (9.07)?

You probably also want to change the line input=thing/100*250; to input=(thing*250)/100;, but again that wouldn't cause a major program hang problem.

i'll try the math changes (although for it to work properly i think i have to divide before i multiply) and i'll check the firmwear, although i believe that is also up to date, (we meet Sundays so i can't check till then)

OK we implemented the math changes suggested earlier, and the brick still froze.

Other observations:
-we were preforming multiple tasks
-the battery power was at about 12.9 volts

The most effective thing we have done to fix this was to have a strip of wire hanging from the bottom of our robot touching the ground. FIRST recommends this and it is supposed to ground the extra charge on the robot.

I didn't know that the robot built up charge, and that it caused problems. I have gotten some nasty static shocks cleaning up fields in the winter though.

that fixed our problems as well with the nxt freezing...we just added a wire to the bottom.