We are using Baby Orangutan B-328 and trying to connect it with PC using serial cable (RS-232). We have used pins pd0 and pd1.
We are able to receive commands from PC to 3PI but 3PI is not able to send data/commands to PC. We do get some random data sometimes when we send more than 2 bytes using pololu serial transmitter.
Good guess, we are not using any circuit in between.
Initially we tried to interface using Xbee wireless module in which we were able to send data from PC to 3PI but not vise versa. We keep trying by making adjustments in program and finally connect RS-232 directly as an troubleshooting step. We got same results in both cases.
Can you please point me to a reference for in between circuit? Is that also required for Xbee?
You’re really asking for destroying your electronics when you don’t pay attention to voltage levels. You should do a search for something like “RS-232 adapter circuit” to learn more.
How are you programming your Orangutan and 3pi? If you’re using our programmer, there’s a USB-to-serial adapter built in, so you can use that. It’s already at 5V TTL levels, so you don’t need any other adapter, and the PC side will still look like a COM port.
For the Xbee, you should look at the specifications for its I/O lines. They’re probably not RS-232 levels. If they are running at 3.3V, you might need some adapter to 5V signals, too, but a lot of things that run on 3.3V are 5V tolerant. So, you have to check for your particular devices.