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Here you go, 'unverified' code.
Code:@ device PIC16f84, HS, NOWDT, PROTECT, PUT ltime var word PIN_B7 var PORTB.7 TRISB = 0 for ltime = 0 to 50 PIN_B7 = 1 pause 50 PIN_B7 = 0 pause 50 next while (1) PORTB = 1 pause_us(59) PORTB = 2 pause_us(59) PORTB = $41 pause_us(59) PORTB = $42 pause_us(59) wend /////////////////////// the end !! ////////////////////////////////////////
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That was very nice of you, Jerson, to take the time to do that. I think I agree with your conversion - while I have no prior knowledge of C, I'm studying Java at the moment and starting to many similarities between them.
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Thank you.I will try.Originally Posted by Jerson
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If you're going to convert this to produce the same timing at 4MHz, you'll
need to use an assembler delay routine.
At 20MHz, like the original C version, delay_cycles(59); gives you a delay of
59 * 200nS instruction cycles. 59 * 200nS = 11.8uS.
PAUSEUS at 4MHz is limited to a minimum delay period of 24uS, and with an
instruction time of 1uS at 4MHz, you're still going to be off by a minimum of
200nS.
12uS is about as close as you can get to the original 11.8uS delay period.
This would give you very close to the same program & timing. The differenceCode:' For 4MHz use XT_OSC @ DEVICE PIC16F84A, XT_OSC,WDT_OFF,PROTECT_OFF,PWRT_ON DEFINE OSC 4 ltime VAR BYTE GOTO Main PAUSE12: ' CALL to here = 2uS ASM GOTO $+1 ; 2uS GOTO $+1 ; 2uS GOTO $+1 ; 2uS GOTO $+1 ; 2uS RETURN ; 2uS (12uS total delay time) ENDASM Main: TRISB = 0 FOR ltime = 0 TO 49 ' 50 loops total PORTB.7 = 1 PAUSE 50 PORTB.7 = 0 PAUSE 50 NEXT ltime WHILE (1) PORTB = 1 CALL PAUSE12 PORTB = 2 CALL PAUSE12 PORTB = $41 CALL PAUSE12 PORTB = $42 CALL PAUSE12 WEND END
is the delay between port updates in the WHILE loop are 12uS VS 11.8uS.
Last edited by Bruce; - 22nd July 2007 at 15:34.
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Thank you.
I want to test this code with Attached Image.
At port.0 and port.1 must have 38khz and at port.6 must have 19khz
Last edited by savnik; - 22nd July 2007 at 16:19.
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You may get the code to work but I dont see how that schematic is going to work if you are trying to build a stereo encoder for an FM transmitter.
Both audio inputs are labelled as {RIGHT} sorry...R IN L IN {end of edit} instead of right and left and the circuit appears to just chop both inputs up at a rate of 38kHz. Presumably the PIC is outputing the two 38kHz signals out of phase otherwise you may as well use the same signal !!!
FM broadcasts were designed to be Mono compatable so have a mono audio signal (L+R) with a difference signal (L-R) carried on a 38kHz subcarrier.
The 19kHz carrier is to operate the pilot indicator in the receiver and switch on the demux to regenerate the original Left and Right signals from Mono + Side.
http://www.irational.org/sic/radio/tech.html#Stereo
gives a block schematic of a stereo encoder which is totally different from what your schematic seems to do.
Last edited by keithdoxey; - 22nd July 2007 at 16:50. Reason: Looked at picture again and saw Mono in not just right!
Keith
www.diyha.co.uk
www.kat5.tv
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For 38kHz on RB0 & RB1, and 19kHz on RB6, you'll need to modify the delay
routines. This should work for ~38kHz & 19kHz. It's off by a few 100Hz, but
a lot closer than the other version.
Code:' For 4MHz use XT_OSC @ DEVICE PIC16F84A, XT_OSC,WDT_OFF,PROTECT_OFF,PWRT_ON ' For 4MHz use DEFINE OSC 4 ltime VAR BYTE TRISB = 0 GOTO Main PAUSE9: ASM GOTO $+1 ; 2uS GOTO $+1 ; 2uS GOTO $+1 ; 2uS NOP ; 1uS RETURN ; 2uS ENDASM PAUSE7: ASM GOTO $+1 ; 2uS GOTO $+1 ; 2uS NOP ; 1uS RETURN ; 2uS ENDASM Main: FOR ltime = 0 TO 49 ' 0 TO 49 = 50 loops total PORTB.7 = 1 PAUSE 50 PORTB.7 = 0 PAUSE 50 NEXT ltime WHILE 1=1 PORTB = 1 CALL PAUSE9 ' CALL = 2uS PORTB = 2 CALL PAUSE9 PORTB = $41 CALL PAUSE9 PORTB = $42 CALL PAUSE7 ' Compensates for GOTO beginning of WHILE loop WEND END
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I have made the pcb and these days i will try if work.
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