Receiving Packet Array In Usart

[mister_e]

Pretty sure DarrEl's routine will help.

Nothing bad to wait between each character to send... kinda character pacing.. sort of.

[crhomberg]

Sorry Darrel for spelling your name wrong, I have only tried your blinky program so far but I am really impressed and exited.
Now I just have to do the same but with the interrupt from the USART receiver.

Thanks

[crhomberg]

Dear Darrel,

If you are still there, please read this adaption of my code to use your instant interrupts.
Something is still not right, it does not seem to get the values.

'************************************************* ***************

'JUST NEED TO SEND THE VALUE IN EACH BYTE ONCE THE PACKET HAS BEEN COLLECTED

'************************************************* ***************
'@ device hs_OSC, wdt_on, pwrt_on, protect_off
define osc 20
Include "modedefs.bas"
INCLUDE "DT_INTS-14.bas" ' Base Interrupt System
INCLUDE "ReEnterPBP.bas" ' Include if using PBP interrupts

trisc.6=0
TRISC.7=1
TRISA.0=0


RCSTA = %10010000 ' ENABLE USART AND SET TO CONTINUOUS RECEIVE
SPBRG = 64 'SET TO 4800bps
INTCON = %11000000 'ENABLE GLOBAL & PERIFERAL INTERRUPTS
RCIF VAR PIR1.5 'FLAG IS THE INTERRUPT WHEN A BYTE IS IN THE USART BUFFER
RCIE VAR PIE1.5
OERR VAR RCSTA.1
CREN VAR RCSTA.4
test var porta.0
BAUD CON 16390
start var bit

BUFFER VAR BYTE[8] 'BUFFER FROM USART TO COLLECT THE 8 BYTES
PELCO VAR BYTE[8]
BYTECOUNTER VAR BYTE 'USED TO COUNTER BYTES INTO THE BUFFER
BFULL VAR BIT 'FLAGS THAT THE BUFFER HAS ALL 8 BYTES
VALUE VAR BYTE 'A TEMP SINGLE BYTE RECEIVED FROM THE USART
COUNTER VAR WORD 'USED FOR LOOP IN MAIN PROGRAM
GOT VAR BIT 'USED TO PREVENT REPEATED SENDING OF SAME PACKET VIA SEROUT2

ASM
INT_LIST macro ; IntSource, Label, Type, ResetFlag? GOTO MAIN:
INT_Handler RX_INT, _GETDATA, PBP, yes
endm
INT_CREATE ; Creates the interrupt processor disable
ENDASM

@ INT_ENABLE RX_INT ; enable RX USART interrupts



PELCO=0
BUFFER = 0
BYTECOUNTER = 0
BFULL = 0
VALUE = 0
RCIE=1 'ENABLE USART RECEIVE INTERRUPT FLAG
GOT=0



'================================================= ====================================

MAIN:



if counter= 5000 THEN 'SEND PELCO VALUE EVERY FEW LOOPS

IF GOT=1 THEN 'IF THE PACKET IS NEW THEN SEND ELSE JUST KEEP LOOPING
serout2 test,BAUD,[HEX BUFFER[0],",",HEX BUFFER[1],",",HEX BUFFER[2],",",HEX BUFFER[3],",",HEX BUFFER[6],10,13] 'JUST CHECK 1ST 2 VALUES
GOT=0
ENDIF
toggle portd.1 'LED TO INDICATE TO ME THAT THE LOOP IS LOOPING
counter=0
else
counter=counter+1
endif

goto main

end


'====================INTERRUPT ROUTINE ==============================

GETDATA:

TOGGLE PORTD.0
IF RCIF=1 THEN

VALUE=RCREG
IF VALUE = $A0 THEN 'CHECK TO SEE IF THE BYTE IS THE START BYTE
BYTECOUNTER=0
ENDIF


IF BYTECOUNTER < 8 THEN
BUFFER[BYTECOUNTER] = VALUE 'ADD BYTE TO PACKET
BYTECOUNTER=BYTECOUNTER+1 'INCREMENT COUNTER
ENDIF

'CHECK IF OVERRUN HAS OCCURRED:

IF OERR=1 THEN
Serout2 test,BAUD,["OERR",10,13] 'TO SHOW OVERFLOW
PAUSE 1000
CREN=0 'STOP CONTINUOUS RECEIVE
CREN=1 'RESTART CONTINUOS RECIEVE & CLEAR THE OVERRUN FLAG
BYTECOUNTER=0 'RESET COUNTER AS PART OF PACKET HAS BEEN LOST SO START AGAIN
BUFFER=0
GOTO GETDATA
ENDIF

'*** PACKET MUST START WITH $A0 AND HAVE $AF AS IT'S 7TH BYTE. ******
IF BYTECOUNTER=7 AND BUFFER[0]=$A0 AND BUFFER[6]=$AF THEN
GOT=1 'INDICATE THAT THIS IS A NEW PACKET
GOTO MAIN 'RETURN TO MAIN PROGRAM
ELSE
GOTO GETDATA 'GO BACK AND WAIT FOR NEXT PACKET
ENDIF
ENDIF


@ INT_RETURN
'================================================= ====================================

[skimask]

Which PIC are you using?
(unless I missed something, I don't think that's ever been established...)

[crhomberg]

I am using the PIC16F977A

[skimask]

I am using the PIC16F977A

I missed those datasheets

[Archangel]

http://www.picbasic.co.uk/forum/showthread.php?t=3251

Unless I misread your code as follows:

@ device hs_OSC, wdt_on, pwrt_on, protect_off

You are using PM as the assembler, and according to this link, DT interrupts require MPASM.
HTH
JS

[mister_e]

i know i miss something here, but i feel lazy to read that carefully... Anyways is the SEROUT2 baudrate should be really 38400 baud, Driven, Inverted, No parity?

[Darrel Taylor]

Oh my, look what happened while I was out trying to make a buck, (a.k.a. at work).

That's the most "unless I missed something"'s I've ever seen in a row.

Chris,

You can't jump out of the Interrupt handler back to the main loop.
Instead, you should just use your GOT flag to indicate reception, then let the main loop handle it at it's leisure.

 IF BYTECOUNTER=7 AND BUFFER[0]=$A0 AND BUFFER[6]=$AF THEN
     GOT=1  'INDICATE THAT THIS IS A NEW PACKET                    
    GOTO MAIN   'RETURN TO MAIN PROGRAM
 ELSE
    GOTO GETDATA   'GO BACK AND WAIT FOR NEXT PACKET
 ENDIF
ENDIF
                
@ INT_RETURN

I think this might work better for the Main loop ...

MAIN:
    IF GOT=1 THEN  'IF THE PACKET IS NEW THEN SEND ELSE JUST KEEP LOOPING
        GOT=0
        GOSUB ShowBuffer
    ENDIF

    if counter= 5000 THEN 'SEND PELCO VALUE EVERY FEW LOOPS
        counter=0 
        GOSUB ShowBuffer
        toggle portd.1 'LED TO INDICATE TO ME THAT THE LOOP IS LOOPING
    ENDIF

    counter=counter+1
goto main


'==========================================================================
ShowBuffer:
    serout2 test,BAUD,[HEX BUFFER[0],",",HEX BUFFER[1],",",HEX BUFFER[2], _
    ",",HEX BUFFER[3],",",HEX BUFFER[6],10,13]  'JUST CHECK 1ST 2 VALUES
return

But, you'll still need to fix the Interrupt handler.

HTH,

[sougata]

Hi,

In your code you are assuming that the first byte at buffer[0] is the pelco-p header.

IF BYTECOUNTER=7 AND BUFFER[0]=$A0 AND BUFFER[6]=$AF THEN
GOT=1 'INDICATE THAT THIS IS A NEW PACKET 
GOTO MAIN 'RETURN TO MAIN PROGRAM
ELSE
GOTO GETDATA 'GO BACK AND WAIT FOR NEXT PACKET
ENDIF
ENDIF

This might not be the case as you may have a dataset misaligned say for one missed byte or corrupted data. So you actually do not know that if your buffer is perfectly aligned. I think you should consider a better algo for checking the PELCO strings.

I assume are using serout2 for your debug purposes. Why not use the TX part of the USART? Yes limitation are that you need to use the same speed as the RX. DT's INT routines takes a finite time to take action in your PBP routine as it saves all the variables for you and checks all the flags and execution orders (aka all the hardwork that we were supposed to do) but please note that it responds to the interrupt instantly. This may screw up the soft serial out routines of PBP as it will introduce timing jitters in the output serial streams. Hope Darrel can enlighten more.

I wish that I actually find some spare time this weekend to get something useful for you. Hope you succeed before that.

[crhomberg]

It's finally running just as I wanted it,

Thanks very much to skimask, Suagata ans especially Darrel Taylor for your help. I could never have got it right. I now can use this code as a "plug in" for all my 8byte protocol coms projects.

I hope I will be able to help you someday as you helped me.

Best Regards

Chris Rhomberg