Remote Control Project

[geocool]

I'm trying to control my sony TV with the IR Transmiter.
I Need to send signal for 2.4ms then pause for 0.6ms and then send 1.2ms for Binary-1 or 0.6ms for Binary-0 with a pause of 0.6ms between them.

http://www.zbasic.net/forum/about676.html
I found this topic where there is OutBurst subroutine that i can use as freqout.I searched in documents for a pause subroutine and i noticed that pause and delay subroutines use seconds.And the question is how can I use μS ? Also will OutBurst work for what I wanna do ?

Thanks In Advance

[dkinzer]

how can I use μS ? Also will OutBurst work for what I wanna do ?

I don't think that you're going to get the precise timing that you need using a pause/delay strategy. A better approach is to use an external oscillator running at the IR carrier frequency (typically 36KHz to 40KHz) and then use OutputCapture() to generate a pulse stream to modulate (i.e. turn on and off) the carrier frequency. Examples of gated IR oscillators can be found in many places on the Internet including this one.

[twesthoff]

Don-
Back in 2008 you helped me generate a 40Hz signal on pin D.7.
If it can make a 40KHz pulse, that might mean an external source may not be necessary for the IR signal.
Here is the code I used then. Can this method be used at 40KHz?
Tom

Code: Select all

Sub Output40HzOn()
       'Turns on 40Hz signal at pin D.7, Divided by 2 for 20Hz in PLD
       'Used to pulse Ctone at 20Hz for incoming call ringing
       Const T2mode As Byte = bx0001_1111
       Register.TCCR2 = 0                                 'Stop Timer2
       Register.TCNT2 = 0
       Register.OCR2 = 180                                 '40Hz=(14745600/1024/20/2)=180
       Register.TCCR2 = T2mode               'Start Timer2
     End Sub

On 8/4/2011 12:14 PM, ZBasic wrote:

geocool wrote: how can I use μS ? Also will OutBurst work for what I wanna do ? I don't think that you're going to get the precise timing that you need using a pause/delay strategy. A better approach is to use an external oscillator running at the IR carrier frequency (typically 36KHz to 40KHz) and then use OutputCapture() to generate a pulse stream to modulate (i.e. turn on and off) the carrier frequency. Examples of gated IR oscillators can be found in many places on the Internet including this one.



- Don Kinzer

[dkinzer]

Can this method be used at 40KHz?

Sure. The code below, adapted from yours, will generate a 38.4KHz signal on the OC2A pin. The physical pin corresponding to OC2A varies across devices. It corresponds to D.7 of mega644/mega1284-based devices and appears on pin 25 on the 24-pin ZX devices.

Code: Select all

Sub Output38KHz()
   If Semaphore(Register.Timer2Busy) Then
     'Turns on 38.4KHz signal at pin D.7
     Const T2modeA As Byte = bx0100_0010  ' toggle OC2A on match
     Const T2modeB As Byte = bx0000_0010  ' div by 8
     Call PutPin(D.7, 0)                  ' make OC2A pin an output
     Register.TCCR2B = 0                  'Stop Timer2
     Register.TCNT2 = 0
     Register.OCR2A = CByte(14745600\8\38400\2-1)
     Register.TCCR2A = T2modeA
     Register.TCCR2B = T2modeB            'Start Timer2
   End If
EndSub

[edit: added use of timerBusy flag]

[dlh]

Nearly all IR receivers have very wide carrier bandwidth (e.g.±5kHz) and are tolerant of ± 10% variation in pulse/space durations so precision is not a necessity. Many IR protocols date back 40+ years when components were themselves less precise, especially for battery powered remote controls.