Receiving Packet Array In Usart

[crhomberg]

I have a system that uses a control protocol of 8 bytes where it has a start byte which is always $A0 and an End byte which is always $AF. The bytes in between are for control and the 8th one is the checksum (I am not worried about that.
I got my USART recieving the data fine byte by byte but cannot but them in separate variables in correct order or in an array with 8 values.
I wrote this code but it just stays dead.
I need the interrupts as the program has to use the bytes to control a camera after it receives the packet and maybe another may come to cancel the previous.

My Code:
'************************************************* *******
'* PELCO PROTOCOL RECEIVER TO RECEIVE 8 BYTES WHEN INTERRUPTED *
'* PACKETS ALAYS START WITH BYTE1 = $A0 AND BYTE7 = $AF *
'************************************************* ********
@ device hs_OSC, wdt_on, pwrt_on, protect_off
define osc 20
Include "modedefs.bas"

RCSTA = %10010000 'Enable the Usart receive function
SPBRG = 64 'Set to 4800 bps
INTCON = %11000000 'Enable Global & Periferal Interrups
PIE1.5=1 'enable receive interrupt flag

trisc.6=0
TRISC.7=1 'usart input pin
TRISA.0=0


test var porta.0 'Output pin to PC to test values received
counter var word 'Used in the keep-busy loop
BAUD CON 16390



PELCO VAR BYTE[8] 'Packet of data received from the input
BYTECOUNT VAR BYTE 'Counter to put each byte in it's correct position

BYTECOUNT=0
PELCO=0

'---------------------------------jump over your interrupt routines
goto main
'-----------------------------------------------------------------

on interrupt goto myroutine


'******************* interrupt routine *********************
disable

myroutine:
if PIR1.5=1 then
PELCO[BYTECOUNT]=RCREG
IF RCREG=$AF THEN
GOSUB SENDATA
PIR1.5=0
ELSE
BYTECOUNT=BYTECOUNT+1
GOTO MYROUTINE
ENDIF
ENDIF

resume
enable
'************************************************* **

main:

'****************** Loop to keep the PIC busy *************

if counter=5000 THEN 'just to keep the pic busy to make sure the
toggle portd.0 'Toggle LED connected to this pin.
counter=0 ' interrupts are working.
else
counter=counter+1
endif

goto main

end

'********** Send data to PC to check if correct ********

SENDATA:
serout2 test,BAUD,[HEX PELCO[0],HEX PELCO[1],HEX PELCO[2],HEX PELCO[3],HEX PELCO[4],HEX PELCO[5],10,13]
RETURN

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

[skimask]

SPBRG = 64 'Set to 4800 bps
-------------double check this...

-------------Are your A/D pins set to analog or digital?

BAUD CON 16390
-------------double check this too...

myroutine:.................
GOSUB SENDATA
...............................
resume
enable

-----------Not good programming practice to jump out of an interrupt routine and hope it comes back into it every time...might not....

if counter=5000 THEN 'just to keep the pic busy to make sure the
toggle portd.0 'Toggle LED connected to this pin.
counter=0 ' interrupts are working.
else
counter=counter+1
endif

--------------Is the LED toggling?

[crhomberg]

The value of SPBRG at 64 works fine when I tested byte by byte.

My serout2 on PORTA.0 is working fine and the loop is looping (led toggling).
The problem is that as I send data packets to the input it immediatley gets a buffer overrun error.

Regards


Chris

[skimask]

The problem is that as I send data packets to the input it immediatley gets a buffer overrun error.

Which input? The PICs input, PC's input, camera's input...

[crhomberg]

I used to receive the packets using SERIN2 and it works quite well but when the data comes one after another too fast I start loosing packets while the program is out doing other things after the serin2 times out.


'*************** Variables for Receiving Pelco-P data *********

data_1 VAR BYTE ' Header
data_2 VAR BYTE ' ID Camera
data_3 VAR BYTE ' 1st Data
data_4 VAR BYTE ' 2nd Data
data_5 VAR BYTE ' 3th DAta
data_6 VAR BYTE ' 4th DAta
data_7 VAR BYTE ' Trailer
data_8 VAR BYTE ' Checksum

'*************** CONSTANTS ***********************
baud con 16390'Baud rate for test pin output



START:


'**RECEIVE DATA FROM RS485 AND SEE IF IT IS A PELCO-P COMMAND ****

Receiving:


SERin2 DATAIN,188,1000,timeout,[data_1,data_2,data_3,data_4,data_5,data_6,data_7,d ata_8]

timeout:

if (data_1 <> $A0) then 'Check if the 1st byte is Pelco ($A0).
goto receiving
endif

etc.... etc do the decoding....

[crhomberg]

I have my PIC receiving data from a camera PTZ control console using RS485 which sends out data every time I move the joystick telling the PIC what to do. I have a RS485 to TTL converter on the input of the PIC

Regards

Chris

[skimask]

Send out bytes using serout one byte at a time instead of a whole string of bytes and in between sending out bytes, do a quick serin check to see if anything is there.

[crhomberg]

I don't have a choice, the data always comes in groups of 8.
The serout is just for debugging, not really needed finally.
I must be able to read in 8 bytes and then check if the 1st one is $A0 and the 7th $AF. When that is true I can use the data. The packets come at 4800bps and in bursts relatively far apart (That is how I got away with serin2 until now, it just lost packets from time to time)
I need to stop what the program is doing when that 1st byte arrives and then channel in the next 7 into an array or sepparate vars.

Regards

Chris