Serin2,Serout2,Wait problem

[Tobias]

I have six boards, each with either a 18F2620 or 4431 chip talking back and forth through a wireless TX. Here is an example of code

  serout2 WtX,84, ["P",1,OutgoingPop1.lowbyte,OutgoingPop1.Highbyte,OutgoingPop2.lowbyte,OutgoingPop2.Highbyte,_
                       OutgoingPop3.lowbyte,OutgoingPop3.Highbyte,OutgoingPop4.lowbyte,OutgoingPop4.Highbyte,OF1,OF2,Of3,OF4 ]

and then the receiving side.

'   debugin [wait ("P"),UnitID2,TotalRate1.lowbyte,TotalRate1.Highbyte,TotalRate2.lowbyte,TotalRate2.Highbyte,_
'                       TotalRate3.lowbyte,TotalRate3.Highbyte,TotalRate4.lowbyte,TotalRate4.Highbyte,OFI1,OFI2,OFI3,OFI4]

The problem is, even for when I have just two boards talking back and forth is that both boards get into a scenario of both listening and not talking, opposite my marriage. Both are WAITing.

What is the trick to get around this? I was thinking of maybe sending another bit that when received would let the receiver know its ok to send. That seemed maybe feasible when there are only two boards talking back and forth but would get pretty complicated when six are talking. When I say six are talking, there is a main board and five others. The main board just listens to one board and talks back and forth to the other four boards.

[Tobias]

One thing I need to mention the WAIT character I am sending is different between the one board that is just sending and the other boards sending and receiving besides the main board listening to all. I think I need to change the WAIT character to the same for all then add another byte that is the board ID and do a loop that either exits when the ID is met or a counter meets the max. I will try that tonite with many Miller Lites.

[mackrackit]

Add a time-out to the wait.

[Tobias]

I thought TIMEOUT would only work when the incoming line wasn't active at all. If there is data on the input pin even if its wrong Timeout won't happen if I read the info correctly.

[mackrackit]

Here is something from Bruce that will time-out and active serial port. Works very well for radios.

'****************************************************************
'*  Name    : DEC.BAS                                           *
'*  Author  : B. Reynolds                                       *
'*  Notice  : Copyright (c) 2009 Reynolds Electronics           *
'*          : All Rights Reserved                               *
'*  Date    : 11/15/2009                                        *
'*  Version : 1.0 (Momentary decoder version)                   *
'*  Notes   : 4-BIT DECODER IC FOR RF REMOTE CONTROL            *
'*          : USING THE PIC12F635                               *
'****************************************************************
@ DEVICE PIC12F635,MCLR_OFF,INTRC_OSC_NOCLKOUT,WDT_OFF,BOD_OFF
@ DEVICE PWRT_ON,FCMEN_OFF,IESO_OFF,WUREN_OFF,PROTECT_OFF
    
    DEFINE OSC 4
    DEFINE NO_CLRWDT 1      ' Watchdog timer is disabled, so we don't need to reset it
    DEFINE INTHAND RESET_VT ' Interrrupt on Timer1 overflow to reset outputs in 65.5mS
                            ' if no serial data received in this time period
    SYMBOL  MODE = GPIO.3   ' baud select. 1=4800, 0=2400
    SYMBOL  D_IN = GPIO.5   ' Encoder data input pin
    SYMBOL  TMR1IF = PIR1.0 ' Timer1 overflow interrupt flag (reset in int handler)
    SYMBOL  TMR1IE = PIE1.0 ' Timer1 interrupt enable bit
    
    'Variables for saving state in interrupt handler
    wsave    VAR    BYTE $70 system        ' Saves W
    ssave    VAR    BYTE bank0 system    ' Saves STATUS
    psave    VAR    BYTE bank0 system    ' Saves PCLATH
    fsave    VAR    BYTE bank0 system    ' Saves FSR
    
    ' Working variables
    MATCH     VAR BYTE bank0 system ' Match variable
    DAT_IN1   VAR BYTE  ' 1st Data byte
    DAT_IN2   VAR BYTE  ' 2nd Data byte for verify
    CHK_SUM   VAR BYTE  ' Holds checksum received
    CheckSum  VAR BYTE  ' Checksum of data bytes received
    LOOPS     VAR BYTE  ' Loop var
    BAUD      VAR WORD  ' Holds baud rate
    
    ' Constants
    Synch    CON "~"    ' 01111110 synch byte
    N2400    CON 16780  ' 2400 bps inverted
    N4800    CON 16572  ' 4800 bps inverted
    
     ' hardware init
    GPIO = 0            ' Clear outputs on power-up
    TRISIO = 101000  ' GPIO.5=data input, GPIO.3=baud select input
    WPUDA = 0           ' Disable weak pull-ups
    IOC = 0             ' Interrupt on change disabled
    VRCON = 0           ' Comparator Vref disabled
    CMCON0 = 7          ' Disable comparators
    OSCCON = 100000  ' Internal 4MHz select
    OPTION_REG = 128    ' Pull-ups off
    
    ' Setup Timer1 for resets after ~65.5mS
    T1CON = 000000   ' Internal clock, 1:1 prescale, Timer1 off for now
    TMR1L = 0 
    TMR1H = 0           ' Timer1 low & high bytes cleared
    TMR1IF = 0          ' Clear Timer1 overflow flag before enabling interrupt
    TMR1IE = 1          ' Enable Timer1 overflow interrupt
    INTCON = 000000  ' Global & peripheral ints enabled
    MATCH = 0           ' Clear match count
    GOTO    MAIN        ' Jump over int handler
    
ASM
RESET_VT
    movwf    wsave            ; Save W
    swapf    STATUS, W        ; Swap STATUS to W (swap avoids changing STATUS)
    clrf    STATUS            ; Clear STATUS
    movwf    ssave            ; Save swapped STATUS
    movf    PCLATH, W        ; Move PCLATH to W
    movwf    psave            ; Save PCLATH
    movf    FSR, W            ; Move FSR to W
    movwf    fsave            ; Save FSR
    
    ; Do interrupt stuff here
    bcf     T1CON,TMR1ON    ; Stop Timer1
    clrf    TMR1L           ; Clear low byte
    clrf    TMR1H           ; Clear high byte
    bcf     PIR1,TMR1IF     ; Clear Timer1 interrupt flag bit
    clrf    GPIO            ; Clear outputs on button release (or timeout)
    clrf    MATCH           ; Clear match variable
    
    ; Restore FSR, PCLATH, STATUS and W registers
    movf    fsave, W        ; retrieve FSR value
    movwf    FSR                ; Restore it to FSR
    movf    psave, W        ; Retrieve PCLATH value
    movwf    PCLATH            ; Restore it to PCLATH
    swapf    ssave, W        ; Get swapped STATUS value (swap to avoid changing STATUS)
    movwf    STATUS            ; Restore it to STATUS
    swapf    wsave, F        ; Swap the stored W value
    swapf    wsave, W        ; Restore it to W (swap to avoid changing STATUS)
    bsf     T1CON,TMR1ON    ; Re-enable Timer1 before exiting interrupt handler
    retfie                    ; Return from the interrupt
ENDASM
 
MAIN:    
    ' Set data rate
    IF MODE = 1 THEN
       BAUD = N4800
    ELSE
       BAUD = N2400
    ENDIF
      
    ' Fire up Timer1 before entry to serial input routine
    T1CON.0 = 1
    
    ' at 4MHz Timer1 overflows in 65536 * 1uS (~65.5mS) if no Synch byte
    ' and serial data arrive on time. SERIN2 timeout & label options
    ' are useless with a noisy RF receiver output - as noise continually
    ' resets the timeout period causing it to hang forever.
    
    ' Wait for Synch byte, then get new inbound data & checksum
    SERIN2 D_IN,BAUD,[WAIT(Synch),DAT_IN1,DAT_IN2,CHK_SUM]
    
    T1CON.0 = 0    ' Stop Timer1 once we've received data
    TMR1L = 0      ' Clear low byte
    TMR1H = 0      ' Clear high byte
    
    ' / **** Begin data validation **** /
    
    ' Calculate checksum
    CheckSum = DAT_IN1 + DAT_IN2
    
    ' Test new checksum against one received in CHK_SUM
    IF CheckSum != CHK_SUM THEN MAIN ' Failed checksum, return
    
    ' Test data bytes for match
    IF DAT_IN1 != DAT_IN2 THEN MAIN ' Failed data comparison, return
    
    MATCH = MATCH + 1        ' We have a match so increment match count
    IF MATCH = 2 THEN DECODE ' Everything matched twice, we're good
    GOTO Main                ' Else do it all over
    
    ' Everything looking good - so place new data on outputs
    
DECODE:
    ' Place decoded values on port pins..
    GPIO = (DAT_IN1 & 010111)
    DAT_IN1 = !DAT_IN2  ' Destroy the match
    MATCH = 0 
    GOTO MAIN
        
    END

.
The forum is stripping off "%". But you should get the idea.

[Charles Linquis]

Tobias, is there some reason why you aren't using the HARDWARE serial port? Using interrupts on the receive side solves 90% of all problems.

[ScaleRobotics]

If you want to invert your hserial, you can do that with the PIC18 devices. Look in the datasheet at the baudcon register, and set RXDTP and TXCKP. This would let you do things like connect to a computer's serial port without using a max RS232 interface. A little more info here: http://www.picbasic.co.uk/forum/showthread.php?t=10361

[Tobias]

gracias!!!

[Tobias]

it seems that function isn't available for all 18F's including my 4431. Good info to know though.