Receiving Packet Array In Usart

[crhomberg]

Thanks for the example code, I modified it to my variable names and included the main loop but it just gives me vales of 0 for BUFFER, what have I done wrong. I checked if it was interrupting and it is.

Here is my code:

'************************************************* **
@ device hs_OSC, wdt_on, pwrt_on, protect_off
define osc 20
Include "modedefs.bas"
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


BUFFER VAR BYTE[8] 'BUFFER FROM USART TO COLLECT THE 8 BYTES
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


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

ON INTERRUPT GOTO GETDATA

GOTO MAIN:


disable


GETDATA:

if RCIF=1 then 'IF RECEIVE FLAG IS ON

VALUE=RCREG 'READ THE VALUE IN THE USART BUFFER

IF VALUE = $A0 THEN 'CHECK TO SEE IF THE BYTE IS THE START BYTE
BYTECOUNTER=0 'AND SET THE COUNTER TO FIRST BYTE
ENDIF

IF BYTECOUNTER < 8 THEN

BUFFER[BYTECOUNTER] = VALUE

BYTECOUNTER=BYTECOUNTER+1 'INCREMENT FOR NEXT BYTE

IF (BYTECOUNTER = 8) AND (VALUE=$AF) THEN
TOGGLE PORTD.0
GOTO MAIN
ENDIF

ENDIF

'CHECK IF OVERRUN HAS OCCURRED:

IF OERR=1 THEN
Serout2 test,BAUD,["OERR",10,13] 'FOR DEBUGGING SHOW ERROR
CREN=0 'STOP CONTINUOUS RECEIVE
CREN=1 'RESTART CONTINUOS RECIEVE & CLEAR THE FLAG

BYTECOUNTER=0 'RESET COUNTER
GOTO GETDATA
ENDIF

ENDIF

RESUME

ENABLE
'===============================================


MAIN:

ON INTERRUPT GOTO GETDATA

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

serout2 test,BAUD,["BUFFER=",HEX BUFFER.0,HEX BUFFER.1,10,13]
'(JUST CHECK 1ST 2 VALUES)

toggle portd.1 'LED TO INDICATE TO ME THAT THE LOOP IS LOOPING

counter=0
else
counter=counter+1
endif

goto main

end

[crhomberg]

I modified my code and am getting the 8 bytes but seem to keep running into buffer overflows. Can you see an error in my interrupt routine?

'************************************************* ***************
@ device hs_OSC, wdt_on, pwrt_on, protect_off
define osc 20
Include "modedefs.bas"
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


BUFFER VAR BYTE[10] 'BUFFER FROM USART TO COLLECT THE 8 BYTES
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


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

ON INTERRUPT GOTO GETDATA

GOTO MAIN:


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

GETDATA:


IF RCIF=1 THEN

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

RCIF=0

IF BYTECOUNTER < 8 THEN
BUFFER[BYTECOUNTER] = VALUE
BYTECOUNTER=BYTECOUNTER+1
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

IF BYTECOUNTER=7 AND BUFFER[0]=$A0 AND BUFFER[6]=$AF THEN

GOTO MAIN
ELSE
GOTO GETDATA
ENDIF
ENDIF





RESUME

ENABLE
'================================================= ====================================

MAIN:

'ON INTERRUPT GOTO GETDATA

if counter= 1000 THEN 'SEND PELCO VALUE EVERY FEW LOOPS
serout2 test,BAUD,["BUFFER=",HEX BUFFER[0],",",HEX BUFFER[1],",",HEX BUFFER[2],",",HEX BUFFER[3],",",HEX BUFFER[4],",",HEX BUFFER[5],",",HEX BUFFER[6],",",HEX BUFFER[7],10,13] 'JUST CHECK 1ST 2 VALUES
toggle portd.1 'LED TO INDICATE TO ME THAT THE LOOP IS LOOPING
counter=0
else
counter=counter+1
endif

goto main

end

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

[Darrel Taylor]

You've got data coming in at 4800 baud, and data going out a 38400.

So you can send 8 bytes in the time it takes to receive 1 byte.
The USART has a 2 byte buffer, so you can only send 16 bytes (or less) to the PC without expecting to see overflows.

But, In this statement...

serout2 test,BAUD,["BUFFER=",HEX BUFFER[0],",",HEX BUFFER[1],",",HEX BUFFER[2],",",HEX BUFFER[3],","
,HEX BUFFER[4],",",HEX BUFFER[5],",",HEX BUFFER[6],",",HEX BUFFER[7],10,13] 'JUST CHECK 1ST 2 VALUES

depending on the values of the data, it will send up to 33 bytes.

Since you are using ON INTERRUPT, the next interrupt can't happen untill the serout2 statement has finished.
<br>

[crhomberg]

Thanks Darryl,

You hit my problem on the spot, why are the small simplicities the ones that give the most grief?
I am going to look into hardware interrupts to allow me to break out of a serout2 command. Do you have any code that works well? If not, don't worry.
I feel I'm on the right track now.

Thanks All,

Chris

[Darrel Taylor]

I am going to look into hardware interrupts to allow me to break out of a serout2 command. Do you have any code that works well?

I ... uh ... er ... hem ... haw ...

Well, there's this ...

DT-INTS-14
http://www.darreltaylor.com/DT_INTS-14/intro.html
<br>

[skimask]

Thanks Darryl,
You hit my problem on the spot, why are the small simplicities the ones that give the most grief? I am going to look into hardware interrupts to allow me to break out of a serout2 command. Do you have any code that works well? If not, don't worry. I feel I'm on the right track now. Thanks All,
Chris

Or figure out a way you can send one byte at a time and check for an input in between bytes...

[crhomberg]

Tomorrow I want to try Darryl Taylor's instant interrups, I hope that will help.
When I removed or shortened the serout2 string all worked fine so I think if an assembler interrupt can stop the Serout2 before it completes things should work well. Even If I loose a few serout2 lines it is less important then loosing input packets.

Regards

Chris

[mister_e]

Pretty sure DarrEl's routine will help.

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