I’ve managed to get the Atmega16 chip talking to my PC over an RS232 serial link. The Atmega has a built in UART, which makes serial comms easy. You just write the data you want to send into a register and the chip does the rest. A MAX232 chip converts from the 5v levels used by the atmega into +10/-10v used in RS232. I can leave my circuit plugged into the serial line and the in-circuit-programming cable and control everything from my PC. I had to work through a few problems with a logic probe to figure out what was going wrong, which made me think that an oscilloscope would be a Fine Idea. So, a quick trip to ebay resulted in a purchase of a basic but very useful oscilloscope, yay!
I’m trying to get Avrforth running at the moment. It runs okay, but whenever I try to store anything to memory, it hangs. I’m going to dig a bit more into this, but it’s not really directly relevant to the UAV project so I’m not going to spend ages on it.
Next task is to get to grips with timers and PWM input. This will let me use my ultrasonic range finder board, which indicates distance by varying the pulse-width. As ever, there is plenty of information out there about this. I also found an old i2c temperature sensor IC which I might try using too.