To control Small Robot, a simple and easy concept is explained here. Four buttons are used to control the Small Robot, in all the four directions. To make the Robot control small and simple, ATTINT13 (8 pin micro controller) is used for both transmitter and receiver boards.
A Transmitter board, is designed with a micro-controller (ATTINY13) , which receives four inputs from the small buttons and converts to 4 bit data. Then sends the 4 bit data as serial data. The serial data is sent through a wireless transmitter module.
Similarly, Receiver board, is also designed to receive the serial data, through a wireless receiver module. Then, the micro-controller (ATTINY13) decodes the serial data, to four bit parallel data, used as input to motor driver IC (L293D). Thus, motor driver controls the two motors of the Small Robot, for required movement, in all the directions, depending on the keyboard input(s).
For the Keypad Transmitter board, four keys are used to control the direction of motion of Small Robot. Every two keys have parallel connection with two voltage divider resistances. So, by default, the micro-controller receives, mid voltage of power supply (i.e., 2.5V), as input. Two such inputs are used for four input buttons. Both the inputs are connected to the micro-controller's ADC (Analog-to-Digital Converter) pins.
So, when no button is pressed, the micro-controller reads mid value of ADC from both the pins. When, any input button is pressed, the ADC value is set as, either maximum or minimum, depending on the button press. So, the micro-controller always checks the ADC input voltage and converts the ADC value to four bit digital data. Then, the four bits are sent through a pin as serial in encoded form. (Refer Base Frame for four bit data)
Any RF (Radio Frequency) Transmitter may be used, to transmit the Serial data, from the micro-controller to wireless radio wave. A 433 MHz RF transmitter module is used here for the purpose.
A 7805 is used to convert 9V battery supply to 5VDC power supply for the circuit.
For the Keypad Receiver Board, the serial data is received by the RF receiver module, and sent to the micro-controller (ATTINY13). The micro-controller decodes the received data, and converts to four bit parallel data. Then the four bits are sent to the base frame through the 6 pin connector, which in turn controls the movement of the Small Robot.
The 5VDC power supply for Receiver board is derived from the Main board of Base Frame, through 6 pin connector.
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