Wheels + Ping Sensor

After much thought, we decided that we would only use mBeds in our project as opposed to one mBed and one HCS12. Originally, we thought it would be better to use the HCS12 in the car to control the motors since we already learned a lot about PWM in class, but since we need to interface it with the XBees anyway, we decided that it would be best to stick to one platform and learn it well in order to accomplish more with our time. Learning how PWM works in the mBed wasn't too much trouble since a lot of help was provided in the forums.

Moving on, phase two of our project was to add the Ping Sensor to our circuit. The idea is that if there is an object in front of the car, the car will stop even if the user tells it to do otherwise.

The coding wasn't too difficult, but we had a lot of hardware problems. First, we were powering the Ping sensor with an external source and we didn't connect the grounds of the external source and the mBed together. This mistake took us a couple of hours to figure out. Another problem was that for some reason, the USB port of the Mac computer that we were using wouldn't work to power the mBed when we had both the Ping Sensor and the motor working together. Simply changing the connection to a Windows computer solved the problem. We are not sure of why this happened, so maybe Apple can answer that for us.

Next Steps? We will now work on integrating the Xbees with the circuit, so that we have a remote controlled car.