PIC Beginner - Infrared Receiver and IR Protocol

[komoe01]

I'm a beginner for PIC Basic Program. I want to control my PC Program with IR Remote Control. In my place, we can get various IR remote control but a few type of PIC : 16F84A, 16F628A, 16F648A, 16F877A and 18F4550 can available.

I use 16F84A and 4MHz Crystal, RS232 for IR Remote Control.

My first program is IR Remote Receiver with Sony IR Protocol. I choose a DVD Remote Control (Made in China). I tested my receiver to my PC via COM port. It did not work. So I choose universal remote control and assign SONY. Now It's ok.

Secondly, I write my program with RC-5 Protocol. This code is posted by Bruce (http://www.picbasic.co.uk/forum/arch...php/t-308.html) It's also ok for universal remote that assigned for Philips. But it don't work for that DVD Remote Control.

Then I tested simply that DVD Remote Control's IR signal with LED. LED is worked between 900ms and 920 ms. It may be Header of IR train. I searched data of all protocols (http://www.sbprojects.com/knowledge/ir/ir.htm). I thought that DVD remote use NEC protocol. I also found that most of China DVD player's remote control use NEC IR protocol in a manual of DVD Player.

I learn NEC IR Protocol. It's type is different for Sony Protocol. Sony use Pulse Width Modulation [PWM]. But NEC use Pulse Distance Modulation [PDM]. I think that PulsIn is use to measure the pulse width. Is it right? So what is use to measure the distance between pulse. Is it [PulsIn + PAUSEUS]?

For NEC Protocol, I refer dhouston's post (http://www.picbasic.co.uk/forum/show...7859#post77859). My receiver's LED is ok for that DVD remote any key press but in my PC program all signal is Zero.

Any help would be greatly appreciated.

If this receiver is ok, I want to do Universal Infrared Receiver (UIR) with USB (with ref: eg. A universal algorithm for implementing an infrared decoder: www.edn.com/article/CA6653644.html.

Regard

Moe

[dhouston]

A schematic of your IR LED circuitry is necessary so we can see whether you need to measure pulses or spaces. PulsIn measures spaces as well as pulses - you merely need to indicate the polarirty. There are some example circuits here...

• http://davehouston.org/learn.htm

[komoe01]

Thanks for reply

IR LED circuitry is here.( please see attachment ).

I use this circuit and test Sony Protocol. LED is blink for any key and correct key code is accept in PC via RS232.

Here is code for Sony.

'start code for Sony Protocol --------------------------------------------------------------

'PIC 16F84A Sony SIRC Protocol

Include "Modedefs.Bas"
Define OSC 4 ' Set Xtal Frequency

Header var word
Body var word
i var byte
tmp var Byte
irButton var byte
irDevice var byte

irIN var PortA.2 'IR Input
ToCOM var PortB.4 'Serial Data to compute COM port [RS232]

'next time use both Sony and NEC Protocol in a PIC
'Same Key from different remote do different tasks
'eg Key 1 from Sony Remote ----> task1 in PC
' Key 1 from NEC Remote -----> task2 in PC

'SonyLED is blink for Sony and nec LED is blink for NEC Remote
SonyLED var PortB.2 'Green LED for Sony Remote keypress
necLED var PortB.3 'Red LED for NEC Remote keypress (Reserved)

TrisA = %00000100 ' Input RA2 only
TrisB = 0 ' Output All Port B

Start:
LOW SONYLED : LOW NECLED
IRBUTTON=255: IRDEVICE=255

'in Header is Sony 240
Pulsin irin,0,header ' Measure the header length.
if header > 270 or header < 200 then goto Start

'if correct header read body 12 bit
for i =0 to 11
pulsin irin,0,tmp ' Measure the body length.
if tmp >= 90 then
Body.0[i]=1 'in Sony Logic 1 is 120
else
Body.0[i]=0 'in Sony Logic 0 is 60
endif
next

IRBUTTON = Body & %01111111 'Mask 7 bit
IRDEVICE = (Body >>7) & %00011111 'Mask 5 bit

If IRDEVICE=255 then goto start

Serout ToCom ,N9600,[IRBUTTON] 'to PC COM - Port

if IRBUTTON >=0 and IRBUTTON < 255 then
high Sonyled
pause 300
low Sonyled
endif

pause 100
goto start


'end of code for Sony Protocol ------------------------------------------------------

I use this circuit again for NEC or CHINA DVD Remote Control.

' start code for NEC OR that DVD REMOTE -----------------------------
'PIC 16F84A NEC Protocol Protocol

Include "Modedefs.Bas"
Define OSC 4 ' Set Xtal Frequency

DEFINE PULSIN_MAX 968 '>968 RETURNS 0

Header var word
Body var word
i var byte
tmp var Byte
irButton var byte
irDevice var byte

irIN var PortA.2 'IR Input
ToCOM var PortB.4 'Serial Data to compute COM port [RS232]

'nec LED is blink for NEC Remote
necLED var PortB.3 'Red LED for NEC Remote keypress

TrisA = %00000100 ' Input RA2 only
TrisB = 0 ' Output All Port B

Start:
LOW NECLED
IRBUTTON=255: IRDEVICE=255

'in Header is NEC 900
Pulsin irin,0,header ' Measure the header length.
if header < 792 then goto Start

While irIN=0:Wend 'wait pulse

'if correct header read body 32 bit
for i =0 to 31
pulsin irin,0,tmp ' Measure the body length.

If ((tmp<40) Or (tmp>180)) Then start

if tmp >= 75 then
Body.0[i]=1
endif
next

IRBUTTON = Body & %11111111 'Mask 8 bit
IRDEVICE = (Body >>16) & %11111111 'Mask 8 bit

If IRDEVICE=255 then goto start

Serout ToCom ,N9600,[IRBUTTON] 'to PC COM - Port

if IRBUTTON >=0 and IRBUTTON < 255 then
high necLED
pause 300
low necLED
endif

pause 100
goto start

' end of code for NEC OR that DVD REMOTE ----------------------------

LED is blink for Both remote control. But Data in my PC software All keys are same number.

How can I fix it.

Thanks.

Moe

[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.

[dhouston]

Change...

        For i = 0 To 3
          Debug IHEX2(IR[i] REV 8)
        Next

to...

        For i = 0 To 3
          Debug IHEX2 IR[i]
        Next

The bit order is already reversed as the bits are set by...

RF.0(i)=1

[lester]

Moe, you might want to read this article: Controlling the world from your armchair

[lester]

Moe, Infrared remote control decoding maybe considered something of a black art, however, this tutorial will show you that its principals are quite straightforward, and easy to implement on a PIC microcontroler.

Thanks to BASIC’s shallow learning curve, software designs that used to take weeks can now be realised in a just few hours. This article presents software solutions in the PicBASIC Pro language.

You might want to read the article: Controlling the world from your armchair