PIC Beginner - Infrared Receiver and IR Protocol

[dhouston]

From your schematic it appears you are using an IR receiver. Which one?

IR receivers usually are active low while the code I supplied for the NEC protocol was for RF where the receiver is active high. Also, my code was meant to work with the RF transmitter code that accompanied it which used slightly different timing than the NEC IR protocol.

The EDN article is wrong about details of the NEC IR protocol. It is explained in this NEC datasheet.

• http://davehouston.org/Nec6121.pdf

You will need to modify my RF code in order to receive/decode IR codes.

'12F629

@ __config _INTRC_OSC_NOCLKOUT & _WDT_OFF & _MCLRE_OFF & _CP_OFF

DEFINE PULSIN_MAX 1140				'>1140 RETURNS 0
DEFINE DEBUG_REG GPIO
DEFINE DEBUG_BIT 2				'GPIO.2
DEFINE DEBUG_MODE 1 				'Inverted
DEFINE DEBUG_BAUD 9600
DEFINE OSCCAL_1K 1

IR      VAR     byte[4]
pulse   VAR     byte
i       VAR     byte	         	
stx     VAR     word            	'start of transmission

        CMCON = 7                   'comparators off
        Debug "IR NEC PROTOCOL"
init:   IR[0]=0:IR[1]=0:IR[2]=0:IR[3]=0:i=0
        PulsIn GPIO.1, 0, stx	
        If (stx<760) Then init  		
        'debug #stx                 
        While GPIO.1=1:Wend			'wait space
        Repeat
          PulsIn GPIO.1, 1, pulse
          If (pulse>100) Then
            IR.0(i)=1				'set bit
          EndIf
          i=i+1 
        Until (i>31)
        For i = 0 To 3
          Debug IHEX2(IR[i] REV 8)
        Next
        GoTo init

        End

I have not tested the above code (I don't have time to build a circuit with an IR receiver.) and you will need to convert it for your PIC and the pins you are using.

Note also that my code does not deal with the NEC shortcut repeat code.