This is a step-by-step "tutorial" for connecting a Parallax Propeller Proto Board (#32212) to an iRobot Create's 25 pin Cargo Bay Connector.
This schematic includes a 5v i2c interface and some buttons and an LED. These are not needed for the initial connections to the Create, but odds are at some point you will want to know how to connect an LED and Buttons and an i2c interface for other sensors. Initially, just focus on adding the 9v Regulator and make the connections on Port 2 through Port 6 to the DB25 connector on the Create.
You can use Port 0 and 1 for an external Radio for remote control, or use Port 30 and 31, which are used for Programming the Propeller. In that case, use the PropPlug programmer as your Propeller-to-PC Serial interface. This works well for testing without having to add another serial connection to your PC.
The Cargo Bay 25-pin Connector allows us to send commands to the Create via TTL Serial, and receive responses and sensor data from the Create. Pins are also available to monitor the Creates Docked Status and Power-on State as well as allowing us to Toggle Power On and Off. We also have access to the Creates battery directly for full-time power, even when the Create is powered-off.
Make a DB25 Male connector with wires connected to the following pins:
Connect Create Pin # to Propeller PORT #
NOTE: I am indicating the PIN # on the Create and the PORT # on the Propeller since, depending on your Propeller Chip, the PORT may be on a different Pin.
NOTE: Any 5v input to the Propeller should have a 1k series resistor. Since the Propeller is a 3.3v device, the 1k resistor will limit the current while allowing standard 2.5v TTL level transitions to work. Resistors are not necessary when outputting to a 5v device.
Download CreateSerialTest.spin, compile and upload to your Propeller. Check the Port #'s in the sourcecode to verify they match the Port #'s you used on your Propeller.
Optional Radio Connection:
That's about it. If I left anything out or you can't get it working, send me an e-mail and maybe I'll be able to help.
Create 25-pin Cargo Bay Connector: