Wireless serial communication question

HI EVERY ONE

i m trying to control a robotic arm with wireless serial communication between two PICs. the sender pic takes and input from a joustick potintiometers and send instructios to the receiving pic. there should be 7 bytes to send using serin command. a preamble byte $55 and 6 control bytes.

i established the serial communication between the two pic successfully. and i tested the received data with lcd. everything works great.

the problem is, when i wrote a PWM routine in the receiving pic, i used TMR0 interrupts. now when i try to reveive data and do PWM. the pic doesnt work.

i tried to figure out whats wrong but i failed

can u help me?

here are the codes. i didnt add potentiometers reading to sender pic. i just tried to test it with numbers.

Code:

---

INCLUDE "MODEDEFS.BAS"

S1 VAR BYTE
S3 VAR BYTE
S4 VAR BYTE
S6 VAR BYTE
S7 VAR BYTE
DC VAR BYTE
DC1 VAR BYTE
DC2 VAR BYTE

CNT VAR BYTE
S1 = 255
S3 = 3
S4 = 44
S6 = 10
S7 = 20
DC = 77


TRISB = 0
PAUSE 500

MAIN:
PORTB.0 = 1
PAUSE 1000
PORTB.0 = 0
PAUSE 1000
PORTB.0 = 1
PAUSE 1000
PORTB.0 = 0
PAUSE 1000


 

DATASEND:
 
SEROUT 7,T2400,[$55,S1,S3,S4,S6,S7,DC]
PAUSEUS 2

GOTO DATASEND

---

the receiver pic code is here

Code:

---

'****************************************************************
'*  Name    : W_ROB_REC.PBP                                      *
'*  Author  : [AHMAD ABU OMAR]                                  *
'*  Notice  : Copyright (c) 2009 [AHMAD ABU OMAR]              *
'*          : All Rights Reserved                              *
'*  Date    : 16/12/2009                                        *
'*  Version : 1.0                                              *
'*  Notes  :                                                  *
'*          :                                                  *
'****************************************************************
'****************************************************************
'* DIFINTIONS
'****************************************************************
define osc 48
INCLUDE "MODEDEFS.BAS"
'****************************************************************
'* VARIABLES
'****************************************************************
S1 VAR BYTE                ' first servo motor position
S2 VAR BYTE
S3 VAR BYTE
S4 VAR BYTE
S5 VAR BYTE
S6 VAR BYTE
S7 VAR BYTE
DC VAR BYTE
DC1 VAR BYTE                ' right DC motor of mobile base
DC2 VAR BYTE                ' left DC motor of mobile base

OLD VAR BYTE                ' a counter variable

 
dc1 = 0
DC2 = 0
S1 = 1
S2 = 255
S3 = 1
S4 = 1
S5 = 255
S6 = 1
S7 = 1


'****************************************************************
'* MAIN PROGRAM START
'****************************************************************
INTCON2 = $F5              ' DISBALE PORTB PULL-UPS, SET TRM0 INTERRUPT TO HIGH PERIORITY
INTCON3 = $C0              ' DISABLE EXTERNAL INTERRUPTS PERIORITY
RCON.7 = 0                  ' DISABLE PERIORITY LEVELS ON INTERRUPTS               
PIE1 = 0                    ' DISABLE ALL PREPHIRAL INTERRUPTS
PIE2 = 0
PIR1 = 0                   
PIR2 = 0
ADCON1 = 15                ' ALL DIGITAL I/O
TRISA = 0
TRISB = %10000000          ' RB7 is input, used to reveive serial data                 
TRISC = 0
LATA = 0
LATB = 0
LATC = 0

INTCON = %00100000          ' ENABLE TIMER0 INTERRUPTS
T0CON = %00000101          ' SET PRESCALAR 64 FOR TMR0, APROX 5us PER INCREMENT
                            ' AND TMR0 WORKING IN 16 BIT MODE
TMR0L = $60                ' SET A BALANCE FOR 20ms PERIOD BEFORE INTERRUPT
TMR0H = $F0
ON INTERRUPT GOTO PW
INTCON = %10100000
T0CON.7 = 1
MAIN:
WHILE 1
PAUSEUS 1

GOSUB RECEIVE
WEND






'****************************************************************
'* PW: INTERRUPT SERVICE ROUTINE
'****************************************************************
DISABLE
PW:
PORTB =%01111111
OLD = 0
TMR0L = 0
PAUSEUS 800
s2 = 255 - s1
s5 = 255 - s4
FOR OLD = 0 TO 255
IF S1<= 0 THEN PORTB.0 = 0:S1 = 1
IF S2<= 0 THEN PORTB.1 = 0:S2 = 1
IF S3<= 0 THEN PORTB.2 = 0:S3 = 1
IF S4<= 0 THEN PORTB.3 = 0:S4 = 1
IF S5<= 0 THEN PORTB.4 = 0:S5 = 1
IF S6<= 0 THEN PORTB.5 = 0:S6 = 1
IF S7<= 0 THEN PORTB.6 = 0:S7 = 1
S1 = S1 - 1
S2 = S2 - 1
S3 = S3 - 1
S4 = S4 - 1
S5 = S5 - 1
S6 = S6 - 1
S7 = S7 - 1

WHILE TMR0L = OLD
WEND

NEXT OLD
TMR0L =  $EF              ' SET A BALANCE FOR 18ms PERIOD BEFORE INTERRUPT
TMR0H =  $F1
INTCON = %10100000
T0CON.7 = 1                ' TIMER0 ON
RESUME
ENABLE

'****************************************************************
'* SUBROUTINE RECEIVE
'****************************************************************
RECEIVE:


serIN PORTB.7,T2400,[$55],S1,S3,S4,S6,S7,DC
PAUSEUS 1
RETURN

---

i m using PIC 16f628a on sending end and 18f2550 on the reciving end

crystals used on both sides are 4 MHz

When I have used SEROUT or SERIN with interrupts I always use them when the interrupts are disable. Serial communications slow down your program a lot. It takes sometime time for SEROUT and SERIN to execute, so for me is better to disable the interrupts first.

Robert

THX FOR YOUR REPLY

robert, i m sending 7 bytes with a baud rate of 2400 . this means 240 byte per second will be recived, that is 0.24 byte per millisecond.

since i m doing a PWM signal, the off time is 18 millisecond ( this is what i can use since it is out of ISR ).

if i disabled the interrupt, and let serin take its time, it may take 7*(1/0.24) = 29 ms. this time i cant afford, since the PWM signal must be 50 Hz ( 20ms) and there is only 18ms free in this period.

got what i mean?

i ll try to recive only two bytes with ur suggestion, should i disable interrupts by writing 'disable' before serin command? and write 'enable' after it?

i ll try what you suggeted

Yes, that is how I do it. I put the SERIN and SEROUT between the disable and enable block. Maybe somebody else here can give you more suggestions.

Robert