Another way to control the Small Robot is, using an IR (infra Red) remote. Here, a handy remote with direction markings is selected for controlling the Small Robot. The IR remote sends a specific pattern of digital signal through its IR LED, based on the button press.
An IR receiver module (TSOP 1738) receives the IR signal from the IR remote and sends to the micro-controller (ATTINY13). Then, the micro-controller decodes the signal and converts it to 4 bit binary code, which is available as D0,D1,D2 & D3 at 6 pin connector. Then, the 4 bit code is received by the motor driver IC (L293D) on the Base Frame, to drive the two B.O. motors accordingly.
(refer Small-Robot Base Frame for motor control codes)
A small 8 pin micro-controller (ATTINY13) is used in Receiver circuit. As the transmitter is IR remote, so there is no need of Transmitter board and micro-controller.
Any IR remote may be used to control the Small Robot. But, the signal generated by the IR remote should be decoded and then it shall be converted to, required 4 bit binary code, to control the Small Robot.
Similarly, any IR receiver with 38KHz carrier frequency may be used, like TSOP1838, TSOP98138, TSOP38328, TSPO38438 etc. The pinouts should match with the circuit.
IR (Infra Red) Transmitter:
The IR remote used in the project is clone to Panasonic Audio remote control, which is easily available at affordable price (The original Panasonic remote is costly and not advisable for our project).
The main advantage with this IR remote is, it has the four direction keys on a handy size. The front two buttons used for volume control are used to rotate the Small Robot in Clockwise and Counter-Clockwise directions.
Most of the IR remotes use 38 KHz carrier frequency. It means, the IR LED of the remote glows on/off for 38000 times per second, which is called as Carrier Frequency. Again, the time of 38 KHz IR LED frequency varies for code generation. Say, to send a digital code '1' , the 38 KHz frequency is available for more time, compared to send code '0', before stopping the Carrier Frequency.
So, a specific pattern of digital code is sent by the IR remote, on each key press. To differentiate or identify the IR code from each IR remote manufacturer, a header code is sent initially and the digital time also varies. (The header code ignored in our case).
IR (Infra Red) Receiver:
In the IR Receiver Board, the IR receiver, TSOP1738, is used, for easy identification of its pin-outs. One of its pin, out of 4 pins, is absent, which makes the pin identification fool proof. (Refer the circuit diagram below for better understanding).
So, the Infra-red signals received by the IR receiver, TSOP1738, filters the Carrier Frequency and sends the digital code to the micro-controller (ATTINY13). An LED is provided to show the status of data reception from the IR receiver.
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.
In case, to use different remote, the IR pattern has to be studied and the Source code is to be modified accordingly (modify the getIRcode() function as required).
The 5VDC power supply for Receiver board is derived from the Main board of Base Frame, through 6 pin connector.
Download file from above link and remove .TXT extension.