In this tutorial we will discuss a simple PC controlled robot. The Robot PC link will be a RS232 serial line. The robot will have only five commands.
- Move forward (RS232 char ‘F’ or ‘f’)
- Move backward (RS232 char ‘B’ or ‘b’)
- Turn Left (RS232 char ‘L’ or ‘l’)
- Turn Right (RS232 char ‘R’ or ‘r’)
- Stop (RS232 char ‘S’ or ‘s’)
To keep things as simple as possible, in this example we will use terminal software RealTerm for sending commands to the robot. Later on a dedicated software can be written on PC end to control the robot.
The Robot’s Hardware
The robot’s hardware will be a simple differential drive using two 200RPM DC Gear motor mounted on a HQ Metal Chassis with a front castor wheel. On the back motors we have mounted plastic wheels. More about differential drive is explained in this tutorial.
The Electronics
The robot is controlled using xBoard v2.0 which has ATmega32 as main CPU and integrated motor drivers. We have connected xBoard v2.0 with PC using a CP2102 USB to UART module.
Connect right motor to MOTOR-A Connector and left motor to MOTOR-B.
Download and Burn the Firmware HEX file
Download the firmware hex file from the link given below and program it to the xBoard v2.0 using a USB AVR Programmer. Make sure the fuse bits are set as follows :-
HIGH Fuse = 0xC9
LOW Fuse =0xFF
CP2102 Module Connection
Connect one side of CP2102 module to USB and other side to xBoard v2.0 as listed below.
| xBoard v2.0 | CP2102 Module |
| RxD | TxD |
| TxD | RxD |
| GND | Gnd |
other pins of CP2102 are unused.
Notes:
- Make sure that CP2102 drivers are installed.
- Jumper JP4 is in Off position (non white side)
- Jumper JP2 and JP3 are in On position (white side)
Finding the COM port number of CP2102 module.
A PC can have several COM ports, each may have some peripheral connected to it like a Modem. Serial Ports on PC are numbered like COM1, COM2 … COMn etc. You first need to figure out in which COM port you have connected the AVR. Only after you have a correct COM port number you can communicate with the AVR using tools such as Hyperterminal. The steps below shows how to get COM port number in case of Virtual COM Ports.
Right Click on “My Computer” icon in Windows Desktop.
Expand the PORT node in Device Manager |
Depending on whether you are using a “USB to Serial Converter” or “CP2102 USB/USART Bridge Module” you have to find the port with following name.
- Prolific USB-to-Serial if you are using Bafo USB to Serial Converter.
- Silicon Labs CP210x if you are using CP2102 chip.
Read more: PC Controlled Robot using ATmega32