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.

[Tobias]

I have the wireless module connected to the hardware serial port pins but I have never used that before. Is there any good reading to learn how?

[Charles Linquis]

It is just as easy as using SERIN/SEROUT

I don't know what speed your chips are running - but.

Use MisterE's PIC Multi-Calc to help you set up the proper DEFINES

Then use something like the following:

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

    CR CON 13
    LF  CON 10

    DataStatus = 0

    INTCON.7 = 1   
    INTCON.6 = 1

        INCLUDE "DT_INTS-18.bas"         ; Base Interrupt System
        INCLUDE "ReEnterPBP-18.bas"     ; Include if using PBP interrupts
  
ASM
INT_LIST  macro    ; IntSource,        Label,  Type, ResetFlag?
               INT_Handler    RX1_INT,    _GetChar,    PBP,  yes           
                endm
    INT_CREATE              
ENDASM

;----------------------------------------------------------------------------

  goto OverISRs:

;------------------------------------------------------------------------------------

GetChar:
          HSEROUT[CR,LF,"At least some data received"]    ;     THIS IS JUST FOR DEBUG!!!  REMOVE IN ACTUAL PGM.
         
                     HSERIN 15,BadData,[wait ("P"),UnitID2,TotalRate1.lowbyte,TotalRate1.Highbyte,TotalRate2.lowbyte,TotalRate2.Highbyte,_
                       TotalRate3.lowbyte,TotalRate3.Highbyte,TotalRate4.lowbyte,TotalRate4.Highbyte,OFI1,OFI2,OFI3,OFI4]
         DataStatus = 1 
        GOTO GoodData
BadData:
          DataStatus.7 = 1
GoodData:

@ INT_ENABLE RX1_INT      
@ INT_RETURN

;-------------------------------------------------
OverISRs:     


MAIN:
      If DataStatus.0  then
         HSEROUT [CR,LF,#UnitID2,#TotalRate1,"  .............................
      endif
      if DataStatus.7 then
         HSEROUT [CR,LF,"Data Error!"]
         DataStatus = 0 
   goto main

I haven't actually tested this but it should work.

[Charles Linquis]

I missed something in my earlier post - between OVERISRs and MAIN you need the line

@ INT_ENABLE RX1_INT


Also, you can use LEDs in place of the HSEROUTs to show you have reached that point in the code (as a debugging aid).

[Tobias]

Charles, thanks I will give that a go when I get back. I am on the road for the next four days.

One other thing I was thinking about today flying from CO to PA...First off here is what I am doing. I am controlling electric motors on a agriculture planter. Each row has an electric motor. For each four rows I have one control box. In the tractor I have a board and touchscreen. The tractor board can be called the master board. It sends the required motor speed to each board for each rows motor. The planter boards then take the speed, do the PID and then report back to the master the row speed.

The thing I was thinking about was right now I have the master sending out data to each board separately. I was wondering if it would be better if it sent out one data packet that had Control Box ID and the four speeds for every control box within one data stream. So for example I have a 16 row planter. There are four control boxes talking back and forth to the master/tractor board. The master sends out four different packets. Each with Control Box ID and the four row speeds. So all four boards are getting data, only one is doing something with it. The other three are waiting for their data. I am wondering if there would be any drawbacks to send out one packet that would be like this

Box1, Speed1, Speed2, Speed3, Speed4,Box2, Speed5, Speed6, Speed7, Speed8,Box3, Speed9, Speed10, Speed11, Speed12,
Box4, Speed13, Speed14, Speed15, Speed16,

Then the tractor only has to take time to send out one data pack and each control box gets speed data every time the tractor sends out data, no waiting for its own data.

Are there any drawbacks to sending longer data streams?

[Charles Linquis]

I think that the "large packet" idea has no drawbacks, and is easier to maintain and code. By the way, I grew up on a farm in southwest Iowa and got my EE degree at Iowa State.

[Tobias]

you will be able to appreciate this then, here is my site

www.grahamelectricplanter.com

I think that the "large packet" idea has no drawbacks, and is easier to maintain and code. By the way, I grew up on a farm in southwest Iowa and got my EE degree at Iowa State.

[BrianT]

I have 6 PICs chattering amongst themselves in a gas mixer. The comms is cable based, not wireless, but there are similarities. I found I had to send a number of preamble characters to get the receivers reliably synchronised. The number of preamble characters and the value of the character need to be chosen with some care in an attempt to get a 'balanced' signal on the line. Sending four $AA or $55 characters then "$" as a 'start of message' works a treat for me.

/code:
Snip from RxPacket:
GetSoM:
serin2 msg, 84, 250, rxpacketdone, [wait ("$")]

GetPktInfo:
for C_A = 0 to 1
serin2 msg, 84, [rxchar[C_A]]
chksum = chksum + rxchar[C_A]
next C_A
pkttype = rxchar[0] : msglen = rxchar[1]

GetPayLoad:
for C_A = 2 to (msglen + 1)
serin2 msg, 84, [rxchar[C_A]]
chksum = chksum + rxchar[C_A]
next C_A

GetEoMandChkSum:
for C_A = 2 to 3
serin2 msg, 84, [rxchar[msglen + C_A]]
next C_A

BadMsgCheck:
if rxchar[msglen + 2] <> "*" then getmessage 'should be EoM.
if rxchar[msglen + 3] <> chksum then getmessage 'try again

Snip from TxPacket:
'Send PreAmble
chksum = 0
for C_A = 1 to precnt
serout2 msg, 84,[preambl]
next C_A

'Send Start of Message
serout2 msg, 84,["$"]

'Send message and accumulate ChkSum
for C_A = 0 to (msglen + 1)
serout2 msg, 84, [txchar[C_A]]
chksum = chksum + txchar[C_A]
next C_A

'Send EoM and ChkSum
txchar[msglen+2] = "*" : txchar[msglen+3] = chksum
serout2 msg, 84, [txchar[msglen+2], txchar[msglen+3]]
pause 5 'time enough for recipient to let go of Ack line
if ack = 0 then sendmessage 'recipient is requesting a repeat

TxPacketDone:
'Message sent or timed out so release CommsBus
TRISB = %11111111

/endcode

HTH
BrianT

[Tobias]

Charles
I am playing around with HSERIN and not having much luck. I am pretty sure I have sorted out the problem and I am hosed for making HSERIN work on this board. WHen I use DEDBUGIN here is the setup info

DEFINE DEBUGIN_REG PORTC
DEFINE DEBUGIN_BIT 7
DEFINE DEBUGIN_MODE 1 ' 1 = inverted, 0 = true

If I am understanding the manual correctly, I can't configure HSERIN for inverted mode.

Here is the HSERIN code

define CODE_SIZE 48
define OSC 8
Include "modedefs.bas"    ' Mode definitions for Serout

INCLUDE "DT_INTS-18.bas"     ; Base Interrupt System
INCLUDE "ReEnterPBP-18.bas"     ; Include if using PBP interrupts 

RCSTA = $90 ' Enable serial port & continuous receive
TXSTA = $20 ' Enable transmit, BRGH = 0
SPBRG = 12  ' 9600 Baud @ 8MHz, 0.16%

DEFINE HSER_RCSTA 90h ' Enable serial port & continuous receive
DEFINE HSER_TXSTA 20h ' Enable transmit, BRGH = 0
DEFINE HSER_SPBRG 12  ' 9600 Baud @ 8MHz, 0.16%
DEFINE HSER_CLROERR 1 ' Clear overflow automatically

''''''''THIS IS WHAT I NORMAL USE TO CONFIGURE TX/RX for SERIAL
'DEFINE DEBUG_REG PORTC
'DEFINE DEBUG_BIT 5                                                                                                        
'DEFINE DEBUG_BAUD 9600
'DEFINE DEBUG_MODE 1    ' 1 = inverted, 0 = true

'DEFINE DEBUGIN_REG PORTC
'DEFINE DEBUGIN_BIT 7
'DEFINE DEBUGIN_MODE 1  ' 1 = inverted, 0 = true
                              
Switch4           var     PortD.0        
Switch3           var     PortE.2            
Switch2           var     PortC.0             
Switch1           var     PortC.3            
MotorSpeed        var     PortC.1            
Population        var     PortC.2             
Enable4           var     PortD.1             
Enable3           var     PortD.2             
Enable2           var     PortD.3             
Enable1           var     PortD.4             
Input1            var     PortB.1             
Input2            var     PortB.4             
Input3            var     PortB.3             
Input4            var     PortD.7             
LCD               var     PortD.5
WTX               Var     PortC.5
WRX               var     PortC.7
StandAlone        var     PortD.6

RPM               var     word
Duty1             Var     Word
Duty2             Var     Word
Duty3             Var     Word
Duty4             Var     Word
Duty1S            data    word      200 '20% Duty Cycle  
Duty2S            data    word      400 '20% Duty Cycle  
Duty3S            data    word      600 '20% Duty Cycle  
Duty4S            data    word      800 '20% Duty Cycle  
HighCycle         var     word
LowCycle          var     word
BCD1              var     byte
BCD10             var     byte       
TotalRate         var     word 
TotalRate1        var     word
TotalRate2        var     word
TotalRate3        var     word
TotalRate4        var     word
RPM1              var     word
RPM2              var     word
RPM3              vaR     WORD
RPM4              VAR     WORD
MotorCount        var     byte              'Tracks motorspeed input
HighTime1         var     word
LowTime1          var     word
HighTime2         var     word
LowTime2          var     word
HighTime3         var     word
LowTime3          var     word
HighTime4         var     word
LowTime4          var     word
TotalTime1        var     word
TotalTime2        var     word
TotalTime3        var     word
TotalTime4        var     word
Freq              var     word
UpperLimit        VAR     word
LowerLimit        VAR     word
ChannelCount      var     byte
TotalTime         var     word
MaxTotalTime      var     word
UnitID            var     byte
EPDID             var     byte
Rate1             var     word
Rate2             var     word
Rate3             var     word
Rate4             var     word
T1                var     word  'Used to measure RPM
T2                var     word  'Used to measure RPM
T3                var     word  'Used to measure RPM
RSTATE1           var     byte
RSTATE2           var     byte
RSTATE3           var     byte
RSTATE4           var     byte
GoodBad           var     bit
Prefix            con     $FE            
LcdCls            CON     $51         
CursorPS          con     $45          
Backlight         con     $53           
Contrast          con     $52

INTCON.7 = 1   
INTCON.6 = 1
INTCON2.7 = 1         'Pull Ups disabled
ADCON0 = 0            'A/D OFF        
ANSEL0 = %00010000    'All analogue channels to digital except AN4                          
ANSEL1 = %00000000    'All analogue channels to digital
TRISA = %111111       'PortA to inputs
TRISB = %00100000     'PortB to outputs, except B5----------------------------------------------------04
TRISC = %10010110     'PortC, Switch3 and Switch4 outputs; Motorspeed and Population inputs
TRISD = %01000000     'PortD, Switch 1 output; Enable1-4
TRISE = %011 
PWMCON0=%01111111     'All odd PWMs enabled, all independent
PTCON0 = %00001000    '2.0khz=00000100 2.9khz=00000000          '400hz/20Mhz=00001000
Freq= 249             '2.0kHz=249 2.9kHz=50000           '400hz/20mHz=50000
LowerLimit=100        '200 is 6%
UpperLimit=1000       '1000=100% (Max is 3332 3000 is 90% for 2.9khz)
PTPERL =Freq.LowByte              ' 
PTPERH =Freq.HighByte  
Symbol Capture = PIR2.0 ' CCP2 capture flag
Symbol Overflow = PIR1.0
Overflow = 0            '
PWMCON1 = 1             ' updates enabled, overrides sync w/timebase
PTCON1 = %11000000      ' PWM time base is ON, counts up  500hz
FLTCONFIG = %00000000   ' enable fault A, cycle-by-cycle mode
RCSTA.7=1 'SPEN serial port enable bit
INTCON = 0              ' Interrupts off
CCP2CON = %00000101     ' Capture mode, capture on rising edge
T2CON = %10000001       ' TMR1 prescale=1, clock=Fosc/4, TMR1=on
T1CON = %10010001       ' TMR1 prescale=1, clock=Fosc/4, TMR1=on

rpm=0
TotalTime1=0
MaxTotalTime=20000

pause 100
Serout2 LCD, 84, [Prefix,LcdCLS]
pause 10
SEROUT2 LCD,84, [Prefix,CursorPS,0, "EPD HSERINTEST"]
pause 2000
Serout2 LCD, 84, [Prefix,LcdCLS]

'::::::::::::::::::::::::::::::::::::::::::::::::: ::::::::::::::::::::::::::
ASM
INT_LIST  macro    ; IntSource,        Label,  Type, ResetFlag?
        INT_Handler    RX_INT,  _Get_char,   PBP,  yes
    endm
    INT_CREATE               ; Creates the interrupt processor
ENDASM
'::::::::::::::::::::::::::::::::::::::::::::::::: ::::::::::::::::::::::::::
@   INT_ENABLE   RX_INT     ; enable external (INT) interrupts

goto OverISRs:

Get_char:
  HSERIN  100, BadData, [wait ("I"),RPM.LowByte,rpm.highbyte,RSTATE1,RSTATE2,RSTATE3,RSTATE4] 
  GoodBad=1
  goto GoodData
  
  BadData:
  goodBad=0
   
  GoodData:  
@ INT_RETURN

OverISRs: 

RunAround:
  gosub DisplayData
goto RunAround

DisplayData:
  If GoodBad = 1 then
    SEROUT2 LCD,84, [Prefix,CursorPS,0, "Good Data"]
    else
    SEROUT2 LCD,84, [Prefix,CursorPS,0, "Bad Data"]
  endif  
  GoodBad = 0      
return 

MeasureRPM:  
  If MotorCount = 1 then
    If Enable1 = 0 then
      High Switch1
      Low Switch2
      Low Switch3
      Low Switch4
      gosub Get_RPM
      hightime1=HighCycle
      lowtime1=lowcycle
      TotalTime1 = HighTime1+LowTime1                                          
    endif
  endif
 
  If MotorCount = 2 then
    If Enable2 = 0 then
      Low Switch1
      High Switch2
      Low Switch3
      Low Switch4 
      gosub Get_RPM      
      hightime2=HighCycle
      lowtime2=lowcycle
      TotalTime2 = HighTime2+LowTime2          
    endif
  EndIf
  
  If MotorCount = 3 then
    If Enable3 = 0 then
      Low Switch1
      Low Switch2
      High Switch3
      Low Switch4
      gosub Get_RPM      
      hightime3=HighCycle
      lowtime3=lowcycle
      TotalTime3 = HighTime3+LowTime3                    
    endif
  Endif
   
  If MotorCount = 4 then
    If Enable4 = 0 then
      Low Switch1
      Low Switch2
      Low Switch3
      High Switch4
      gosub Get_RPM
      hightime4=HighCycle
      lowtime4=lowcycle      
      TotalTime4 = HighTime4+LowTime4           
    endif 
  endif
  
  If MotorCount = 4 or Motorcount >4 then 
    MotorCount = 1
    else 
    MotorCount = MotorCount + 1
  endif
return

NoRPM:
      HighCycle = 0  ' High pulse width = T2 - T1
      LowCycle = 0
      overflow = 0 
return

Get_RPM:
    pauseus 300 
    Capture = 0          
    CCP2CON = %00000101 
    
    overflow = 0 
    WHILE Capture=0 and overflow=0 
    WEND
    If OVerflow=1 then
      goto NoRPM
    endif 

    T1.HighByte = CCPR2H : T1.LowByte = CCPR2L
    Capture = 0        
    CCP2CON.0 = 0      
    
    WHILE Capture=0 and overflow=0 
    Wend
    If OVerflow=1 then
      goto NoRPM
    endif     

    T2.HighByte = CCPR2H : T2.LowByte = CCPR2L
    Capture = 0        
    CCP2CON.0 = 1     
    
    WHILE Capture=0 and overflow=0 
    Wend
    If OVerflow=1 then
      goto NoRPM
    endif         

    T3.HighByte = CCPR2H : T3.LowByte = CCPR2L
    
    CCP2CON = 0         
    HighCycle = T2-T1   
    LowCycle = T3-T2    
return

BCD:
  BCD1=PORTA
  BCD1=BCD1 & $0F
  BCD1=BCD1^ $0F 
  Unitid=bcd1
  
'  BCD1=PORTA
'  BCD1=BCD1 & $F0
'  BCD1=BCD1^ $F0
'  BCD1 = BCD1 >>4 
'  Unitid=bcd1 
return

[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.