Can't Get PiBot to Move

[scottswanson]

I have my Pi-Bot up and running.  Everything seems to work well except I can't get the motor start and make the robot move.  The LEDs work, as well as the ultrasonic sensor.  Here is a picture of bot.  I've rewired the bot (the motor components) 3 times to see if I had made a mistake with that.  That doesn't appear to be the issue.  I also tried new AA batteries and that doesn't seem to have any effect.  Any suggestions for trouble shooting would be greatly appreciated.

[jasea]

Hi there,
What program are you running on your Pi-Bot, and have you made any changes to it?

Regards

John

[jasea]

Hi again,
Just a very silly question, but have you switched on the motor power switch? Is there 4.5 Vlots, battery voltage, across pins 15 & 16 of the motor controller?

Regards

John

[ron]

I am having similar problem. I purchased Pi-Bot for my grandson for Christmas present. We assembled it. We also installed the software. The LED program compiles and runs on Pi-Bot (red led on 13 blinks). Motor program compiles with no errors but when sent to Pi-Bod, we can hear faint sound coming from somewhere on board that appears to be on and off with timing as expected for program, but wheels do not move. We have checked connections repeatedly and are pretty sure they are all correct. As a test, when I touch red and black outputs from AA battery supply directly to either left or right motor inputs, the wheels turn. I also used voltmeter and it measures 3.67 volts across pins 15 and 15 (power and ground to the chip on the breadboard). I verified that switch from AA battery supply is in on position (tried it both ways and wheels do not move in either position). Not sure what else to check. Can someone tell me what voltages to check on other pins, or other tests to diagnose problem?

[jasea]

Hi Ron,
    The LED program runns off the STEM Board power supply, the 9 Volt battery, so is no indication that the motor power supply is good
    I am very suspicious of the voltage that you are mentioning. You should have a three AA cell pack that should produce 4.5 Volts. Can you measure across the motor switch, the nut and bolt connections are fine. In one position the reading will be 0 Volts, this is the on position. In the other position, the off position, you should read your battery pack voltage. If it is still 3.6 V then try some new cells.
    Let me know what you find.

Regards

John 

[ron]

Thanks John. You are correct that my voltage is a little low. I did not have any new AA so I scavenged some out of other devices. I will buy some new ones later today and try again. However I don't think that is likely to be the problem because when I touch power and ground from battery directly to leads to either motor, wheels turn smooth and fast. I will report back after I have had a chance to install new batteries.

[ron]

You were correct. Bought new AA batteries and all works fine. Apparently my old batteries had enough charge to move wheels when connected to motor directly, but not enough to operate properly through the bridge. Thanks so much for the help.
Ron