Computer Controlled Wireless Robot

The main objective of this project is to design a robot that can be controlled wirelessly from a computer serial port.

It consists of 2 modules

1. Transmitter

The transmitter consists of 8051 module with a serial port and interfaced to a RF Transmitter module. The microcontroller reads the commands sent by the computer from the serial port, interprets for the direction of the robot and sends the command to RF Transmitter and an acknowledgement back to Computer. We have commands such as "Left" - L, "Right" - R, "Forward" - F, "Reverse" - B, "Stop" - S.

For example, if a code "R" is sent from the Computer serial port the microntroller sends "0x01" to RF Transmitter and a string "Right" back to the computer indicating the direction the robot is going to move.

To Interface 8051 with RF Transmitter, we use a Encoder IC HT12E. A0 to A9 on HT12E represents the address and we have it set to 0x00. Data pins D3 to D0 on the encoder is interfaced with P1.0 to P1.3 of 8051. TE pin of encoder is "Transmission Enable" which enables  transmission of data only when it is "Active Low". In our case, the transmission enable is controlled programatically with P1.4 of 8051. The complete circuit is below.



8051 Interfacing with RF Transmitter and Encoder HT12E

2. Receiver

The 8051 interprets the commands received by RF receiver and sends appropriate signals to H- Bridge for the control of the robot.

The receiver consists of

a. RF Receiver
b. Decoder Chip HT12D
c. 8051
d. H-Bridge L293D
e. DC motors.

To Interface 8051 with RF Receiver, we use a DecoderIC HT12D. A0 to A9 is complementary to Address set on Encoder and hence it is 0x00. Data pins D3 t0 D0 are interfaced to pins P1.0 to P1.3 of 8051. Whenever data is received, Pin 17 of the decoder goes high. We use a switching transistor to invert it to "Active Low" to enable us to interface it with "Active Low" INTO Interrupt of 8051. So whenever data is received, INT0 is triggered. The microntroller reads the data from the P1.0 to P1.3 and sends appropriate signals to H-Bridge via P0.0 to P0.3 to control the motors.



8051 Interface with RF Receiver and RF Decoder HT12D