Wired remote for Alpine

[fratello]

Still beta-testing ...
I wonder...It's one way to obtain EXACTLY 536.5 us ?!?

[HenrikOlsson]

Depends.... What's you oscillator speed? At 20Mhz an instruction cycles is 200ns so, in theory, doing something like

PauseUs 536
@ NOP
@ NOP

should get you pretty close (536.4us). If the timing is that critical then it's probably not going to work the way I wrote it since there will be "gaps" between the preamble, command, postamble etc. You'd need to build the complete message in a larger array and then send it but that gets a bit complicated due to the variation in length of the commands (they won't line up at even byte boundries).

/Henrik.

[fratello]

Thank You for support !
The oscillator is 4 MHz...

[HenrikOlsson]

Hi,
Well, at 4Mhz each instruction cycle is 1us so the smallest time possible to resolve at that speed is just that - 1us. I don't think I can come up with any way to get higher resolution without increasing the oscillator speed.

/Henrik.

[fratello]

Understand... so, maybe, I need a 20 MHz oscillator speed.
But first - hardware test ! Best regards !

[fratello]

Mr.Henrik wrote the code...me just put together parts...
BUT : even if in Proteus the signal(s) appears to be OK, the HU-JVC don't react at all !
Maybe the "timming" need to be more accurate ?! At this point, I'm hopeless and stuck ... Any help will be appreciated !
Hex and dns attached...

;***************************************************************************
;*
;*    Test variant, using 2N3904 on output - PORTC.0
;*
;***************************************************************************

@ DEVICE PIC16F684, HS_OSC, WDT_OFF, PWRT_OFF, BOD_OFF, MCLR_OFF
DEFINE OSC 20
include "ALLDIGITAL.pbp"

TRISA= 000011                           
PORTA= 000011

PORTC= 000000
                
CMCON0 = 000111              ' Disable analog comparators.     
VRCON  = 000000               ' Disable Comparator Voltage Reference
ANSEL  = 000000               ' Set pin'S to digital
ADCON0 = 000000               ' Set up A/D converter - OFF 

Pause 1000

i VAR BYTE
j VAR BYTE
OutBuffer VAR BYTE[8]
BitsToSend VAR BYTE


Main:
if porta.0 = 0 then gosub VolUp        ' just for test
if porta.1 = 0 then gosub VolDn        ' just for test

Pause 100                 ' do it for 0.1 sec
Goto Main


'-----------------------------------------------------------------------
SendPreamble:        
; 01110111 01110111 01010101 11
    OutBuffer[0] = 010001 ; 101110 REVERSED BECAUSE OF USING TRANSISTOR AT OUTPUT !!!
    OutBuffer[1] = 010001 ; 101110
    OutBuffer[2] = 010101 ; 101010
    OutBuffer[3] = 111100 ; 000011
   
    BitsToSend = 26
    GOSUB SendBits
RETURN
'-----------------------------------------------------------------------
AGC:
TRISC.0 = 1 ; 0
PauseUs 8584
TRISC.0 = 0 ; 1
PauseUs 4292
RETURN
'-----------------------------------------------------------------------
SendPostAmble:
' 01111111 11111111 11111111 11111111 11110111 01110111 01110101 010111
    OutBuffer[0] = 000001 ; 111110
    OutBuffer[1] = 000000 ; 111111
    OutBuffer[2] = 000000 ; 111111
    OutBuffer[3] = 000000 ; 111111
    OutBuffer[4] = 110000 ; 001111

    
    BitsToSend = 36
    
    GOSUB SendBits
RETURN
'-----------------------------------------------------------------------
SendFinalAmble:
' 01111111 11111111 11111111 11111111 11111111 11111111 11111111 111111
    OutBuffer[0] = 000001 ; 111110
    OutBuffer[1] = 000000 ; 111111
    OutBuffer[2] = 000000 ; 111111
    OutBuffer[3] = 000000 ; 111111
    OutBuffer[4] = 000000 ; 111111
    OutBuffer[5] = 000000 ; 111111
    OutBuffer[6] = 000000 ; 111111
    OutBuffer[7] = 000000 ; 111111
    
    BitsToSend = 54
    
    GOSUB SendBits
RETURN
'-----------------------------------------------------------------------
VolUp:
    Gosub AGC
;==============================    
    GOSUB SendPreAmble    ; one
    ' Volume Up
    OutBuffer[0] = 010101 ; 101010
    OutBuffer[1] = 101010 ; 010101  
    OutBuffer[2] = 111110 ; 000001
    
    BitsToSend = 17
    GOSUB SendBits
    GOSUB SendPostAmble
;==============================    
    gosub SendPreamble    ; two
    ' Volume Up    
    OutBuffer[0] = 010101 ; 101010
    OutBuffer[1] = 101010 ; 010101  
    OutBuffer[2] = 111110 ; 000001
    
    BitsToSend = 17
    GOSUB SendBits   
    GOSUB SendPostAmble
;==============================    
    gosub sendPreamble    ; three
    ' Volume Up
    OutBuffer[0] = 010101 ; 101010
    OutBuffer[1] = 101010 ; 010101  
    OutBuffer[2] = 111110 ; 000001
    
    BitsToSend = 17
    GOSUB SendBits
    GOSUB SendFinalAmble    
RETURN            ; end command
'-----------------------------------------------------------------------

VolDn:
    Gosub AGC
;==============================    
    GOSUB SendPreAmble
    ' 01111010 11110101 0101
    ' Volume Down
    OutBuffer[0] = 100001 ; 011110
    OutBuffer[1] = 010000 ; 101111
    OutBuffer[2] = 110101 ; 001010
    
    BitsToSend = 20
    GOSUB SendBits
    GOSUB SendPostAmble
;==============================
    GOSUB SendPreAmble
    ' 01111010 11110101 0101
    ' Volume Down
    OutBuffer[0] = 100001 ; 011110
    OutBuffer[1] = 010000 ; 101111
    OutBuffer[2] = 110101 ; 001010
    
    BitsToSend = 20
    GOSUB SendBits
    GOSUB SendPostAmble
;==============================
    GOSUB SendPreAmble
    ' 01111010 11110101 0101
    ' Volume Down
    OutBuffer[0] = 100001 ; 011110
    OutBuffer[1] = 010000 ; 101111
    OutBuffer[2] = 110101 ; 001010
    
    BitsToSend = 20
    GOSUB SendBits
    GOSUB SendFinalAmble    
RETURN
'-----------------------------------------------------------------------
SendBits:
    BitsToSend = BitsToSend - 1
    For i = 0 to BitsToSend 
        TRISC.0 = OutBuffer.0[i]
        PauseUs 536
        @ nop
        @ nop  ; for 536.5 us
    NEXT
RETURN
'-----------------------------------------------------------------------
END

[HenrikOlsson]

Hi,
Like I said earlier, with this aproach you're going to get variation in the bit to bit timing when going from preamble to data to postamble etc. You should be able to SEE this on the scope. Also verify that you actually GET 536.4us between bits (I think it'll be a bit more due to the FOR-NEXT loop) and adjust the delay to match exactly.

What I'd try, just to see IF timing is all there is to it is to stitch a complete packet together and send it in one go. Just extend the size of the array and load it up with bits, set BitsToSend accordingly and call SendBits.

/Henrik.