Cytron Technical Forum

Project Name: Mini "Mute" Remote Control (Inspired by Adafruit's "TV-b-gone kit")

Author/Designer: Y H

Project Description: A small remote control with one button. When the button is pressed, it mutes the television. Only Sony TVs are supported, but it can be programmable to support other TVs, provided the respective signal profiles are observed.
The remote control can be also modified to send other codes such as "Turn Off" and others.

Photo/Picture/Figure/Diagram/Flowchart: The remote control data is sent in a bit-width system and modulated by a 36~40kHz carrier wave with a 25% duty cycle. An '1' means with a 600microsec 'low' and a 600microsec 'high', while '0' means 600microsec 'low' and 1200microsec 'high'.

The pulsing of the data can be done by simple delay codes while the carrier waves can be generated by just using the PWM module present in the microcontroller.

The mechanism is simple:
1.) PWM is set up. A 2400milisec pulse is asserted and sent to the target as a 'start'.
2.) The RC then send another 6 bits of information. These 6-bits are for commanding the target to do something.
3.) The RC then send another 4 bits of address information. These 4-bits are address of the target. All of these are transferred from the Lowest Significant Bit.
4.) The command is sent 3 times (1->3). Afterwards, microcontroller goes to sleep to conserve battery.

Source: Sony IR (infrared) remote control codes

Sony Remote Control Code Lists

Use IR_send(<remote control code>) and do it three times in the loop so that the TV can receive it completely.

The 'low' signal shuts (disables) the PWM pin so that no modulating waves are present, while the 'high' signal enables the PWM pin so that the waves comes into the target.

Compiler: MikroC 5.6.0 (code within 2K limits)

Source code: Attached.

Schematics & PCB Docs:

Hardware: PIC16F1503, 2N3904 transistor, IR LED, 270ohm resistor, 10ohm resistor, 10k ohm resistor, push button, 2AA battery holder.

References: Microchip AN1064: IR Remote Control Transmitter. Schematic is based on the application note.

Wow, this is a cool project. At least I can find some use for my 1503 chips bought recently. Only thing is I dont have a Sony TV. I will search for similar infos for my Toshiba and Samsung TV.

Thanks Brian,

Allen

ABSF WROTE:Wow, this is a cool project. At least I can find some use for my 1503 chips bought recently. Only thing is I dont have a Sony TV. I will search for similar infos for my Toshiba and Samsung TV.

Thanks Brian,

Allen

Hello,

You can use other IR protocol - just change the PWM frequency and the duty cycle for the modulating part.

Also, change the no. of bits sent and the Starting pulse.

Btw, have you looked at my "4-voice music box"?

Brian Griffin WROTE:You can use other IR protocol - just change the PWM frequency and the duty cycle for the modulating part.
Also, change the no. of bits sent and the Starting pulse.
Btw, have you looked at my "4-voice music box"?

Thanks, I'll do some googling and see what I can find. There is no hurry as I dont watch too much TV lately as there are too many projects going on....

Yes, I did glance through your posting and downloaded the software and midi file. Havent got time to go through all the links. Looks like lots of difficult theories behind to understand how it works and I dont have a dsPIC to try out at the moment. Will try it out when my work load is less after June. I am still stucked with my RPM generator and Marine engine RPM projects.

Allen

ABSF WROTE:

Brian Griffin WROTE:You can use other IR protocol - just change the PWM frequency and the duty cycle for the modulating part.
Also, change the no. of bits sent and the Starting pulse.
Btw, have you looked at my "4-voice music box"?

Thanks, I'll do some googling and see what I can find. There is no hurry as I dont watch too much TV lately as there are too many projects going on....

Yes, I did glance through your posting and downloaded the software and midi file. Havent got time to go through all the links. Looks like lots of difficult theories behind to understand how it works and I dont have a dsPIC to try out at the moment. Will try it out when my work load is less after June. I am still stucked with my RPM generator and Marine engine RPM projects.

Allen

No worries, mate. These are the tips if you need to fit this to your remote control : search the google for IR protocols for respective TV sets. You will get tons of these. Plus, the PWM module inside has already done a lot of work for you. So, set the duty cycle, frequency and the no. of bits involved for your own TV.

For the music box - if you have listened to much 80s songs, you'll understand Frequency/Phase modulation eventually. The artificial 'clang' and the 'bell' sounds are done by these synthesizers during that time. Or, if you heard of Yamaha OPL3...

This is a nice little weekends project