3-Switch Mini IR Remote Control for PIC10F200




Description

This project is a 3 button mini IR remote control which transmits 12-bit SIRC IR signals as used by Sony remote controls.  It has been designed to work with both the 2-channel relay driver board  and 3-channel relay driver board projects also on this website.

The board uses Microchip’s low cost PIC10F200 microcontroller along with a handful of easy to find  components making it very cheap to construct.  Everything you need to know to build this project, including the firmware code is right here on the project page.

Mini IR Remote Control

Circuit Description

The circuit is very simple.  IC1 is a PIC10F200 microcontroller programmed with firmware to generate a 40Khz carrier modulated with SIRC formatted data.   The three switches are each assigned a different command code that the firmware will transmit via the IR LED when the switch button is pressed.  The whole unit is powered from a CR2032 3 volt lithium coin cell.  When no button is pressed the microcontroller goes to sleep where it consumes around 100nA (0.1μA).  If left unused the battery should last for many years.

When a button is pressed the microcontroller wakes and sends a SIRC device/command sequence by driving transistor Q1 which in turn operates LED1, a 950nM Infra Red LED.  The transistor is used to drive around 100mA through LED1 giving a range of 7 or 8 metres. 

The SIRC data is sent in a burst repeated every 45mS while the switch remains pressed.  The signal modulates a 40Khz carrier with a 24% duty cycle.  In the screen shot below you can see the data bursts (top) and the 40Khz carrier (bottom)

This images shows the 2.4mS start burst, followed by a 1.2mS burst, then six 600μS bursts (the command code 0000001 sent LSB first), then another 1.2mS burst followed by four 600μS bursts
(device id 00001 again sent LSB first)

For more information on the SIRC infrared protocol see:

 

For more detail: 3-Switch Mini IR Remote Control  for PIC10F200




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