Explanation: Sony IR Remote Control Library for Great Cow BASIC

This include file will let you easily read and use the infrared signals from a Sony compatible television remote control. In particular, the remote control transmits a pulse modulated signal, the sensor detects this, and the subroutine in this header file decodes the signal, returning two numbers: one representing the device (television, VCR, DVD, tuner, etc.), while the the other returns the key which has been depressed (VOL+, MUTE, channel numbers 0 through 9, etc.).

This has been tested and confirmed with a fixed remote control purchased surplus for $2.00 from All Electronics, as well as an universal remote control, set to Sony mode.

Moreover it has also been tested with a Panasonic IR sensor and a Vishay sensor, both purchased surplus for about fifty cents.

Every combination performed well, and it is probably the; case that most any garden variety 38 kHz IR sensor will work. The only tricky bit is making sure you get the pinout for your sensor correct; search out the datasheet for whichever device you use.

There are only three pins: Ground Vcc Data

It is essential to filter the power applied to the Vcc pin. Do this by connecting a 100 ohm resistor from the +5V power supply to the Vcc pin, and bridge the pin to ground with a 4.7uF electrolytic capacitor.

The Data pin requires a 4.7k pullup resistor.

There is only one constant required of the calling program. It indicates which port line the IR sensor is connected to. For example,


There is one subroutine:

    readIR_Remote(IR_rem_dev, IR_rem_key)

The values returned are, respectively, the device number mentioned earlier and the key that is currently pressed. Both are byte values.

Seventeen local bytes are consumed, and two bytes are used for the output parameters. That’s a grand total of nineteen bytes required when invoking this subroutine.

Header File

    sub readIR_Remote(out IR_rem_dev as byte, out IR_rem_key as byte)
      dim IR_rem_count, IR_rem_i as byte
      dim IR_rem_width(12) as byte            ;pulse width array

        IR_rem_count = 0                      ;wait for start bit
        do while IR_DATA_PIN = 0              ;measure width (active low)
          wait 100 uS                         ;24 X 100 uS = 2.4 mS
      loop while IR_rem_count < 20            ;less than this so wait

      for IR_rem_i = 1 to 12                  ;read/store the 12 pulses
          IR_rem_count = 0
          do while IR_DATA_PIN = 0            ;zero = 6 units = 0.6 mS
            wait 100 uS                       ;one = 12 units = 1.2 mS
        loop while IR_rem_count < 4           ;too small to be legit

        IR_rem_width(IR_rem_i) = IR_rem_count ;else store pulse width
      next IR_rem_i

      IR_rem_key = 0                          ;command built up here
      for IR_rem_i = 1 to 7                   ;1st 7 bits are the key
        IR_rem_key = IR_rem_key / 2           ;shift into place
        if IR_rem_width(IR_rem_i) > 10 then   ;longer than 10 mS
           IR_rem_key = IR_rem_key + 64       ;so call it a one
        end if

      IR_rem_dev = 0                          ;device number built up here
      for IR_rem_i = 8 to 12                  ;next 5 bits are device number
        IR_rem_dev = IR_rem_dev / 2
        if IR_rem_width( IR_rem_i ) > 10 then
           IR_rem_dev = IR_rem_dev + 16
        end if
    end sub