16F877A stack problems

Problem: 16F877a begins sending a infinite series of "1" as output to the RS232 conveter.

From the best I can tell the error originates in my "If Command=Q" statement where I read the TEMP2 on a DS18S20 sensor. I assume I am screwing up the stack somewhere, but I can not tell where.

Here's the code, can someone please tell me where I went wrong:

include "modedefs.bas"

DEFINE OSC 20
DEFINE ADC_BITS 10 ' Set number of bits in result
DEFINE ADC_CLOCK 2 ' Set clock source (3=rc)
DEFINE ADC_SAMPLEUS 100 ' Set sampling time in uS

DEFINE HSER_TXSTA 24H
DEFINE HSER_RCSTA 90H
DEFINE HSER_BAUD 9600
DEFINE HSER_CLROERR

'LCD SETTINGS
DEFINE LCD_DREG PORTD
DEFINE LCD_DBIT 4
DEFINE LCD_RSREG PORTD
DEFINE LCD_RSBIT 2
DEFINE LCD_EREG PORTD
DEFINE LCD_EBIT 3
DEFINE LCD_BITS 4
DEFINE LCD_LINES 4

COMMAND VAR BYTE[2]

COUNTR VAR BYTE
COUNTC VAR BYTE
DS18S20F VAR WORD
DS18S20 VAR WORD

TEMP1 VAR PORTB.7
TEMP2 VAR PORTB.6

'LIGHTS
PUMP1 VAR PORTC.1
LIGHT VAR PORTE.2

'I/O CONFIGURATION
TRISA=%00011111
TRISB=%00000000
TRISC=%11001011
TRISD=%11110001
TRISE=%00000000

'USART SETTINGS
PIE1=%01110000
RCSTA=%10010000 'ENABLE SERIAL PORT AND RECEPTION
TXSTA=%00100100

'Turn everything off at startup
LOW LIGHT
LOW PUMP1

LCDOUT $FE,1, "RESET"
HSEROUT ["MARINETIX ZEOSC 1.0"]
PAUSE 1000
HSEROUT ["KX"] 'power up responce

MAIN:

If PIR1.5=1 then 'if there is something in the UART buffer read it in
HSERIN ,2000, TIMEOUT, [STR COMMAND\2] 'IF THERE IS SOMETHING IN THE RECIEVE REGISTER STORE IT IN COMMAND
GOSUB EXECUTE
TIMEOUT: 'if it times out, just start over at main
ENDIF

GoTo MAIN

'***** EXECUTE THE INCOMING COMMAND BASED ON THE CHARACTERS RECIEVED ****

EXECUTE:
IF COMMAND(0) = "K" THEN
HSEROUT ["KX"]
ENDIF

IF COMMAND(0)="T" THEN

LOW TEMP1 'initialize DS18S20
PAUSEUS 500 'wait for return pulse
TRISB.7=1 'set pin as input to get temp reading
PAUSEUS 100

IF TEMP1=1 THEN
DS18S20F=999 'VB error code signaling no sensor connected
HSEROUT ["T", DEC (DS18S20F),"X"]
RETURN
ENDIF

PAUSEUS 400

'START TEMP READING
OWOUT TEMP1, 1, [$CC, $44] ' $CC-SKIP SEARCHING FOR MULTIPLE DS18S20, $44-START

WAITFORCONVERSION:
OWIN TEMP1, 4, [COUNTR] 'CHECK FOR STILL BUSY CONVERTING SIGNAL
IF COUNTR=0 THEN WAITFORCONVERSION

OWOUT TEMP1, 1, [$CC, $BE] 'READ THE TEMPERATURE
OWIN TEMP1, 0, [DS18S20.LOWBYTE, DS18S20.HIGHBYTE, SKIP 4, COUNTR, COUNTC]

DS18S20=((DS18S20>>1*100)-25)+(((COUNTC-COUNTR)*100)/COUNTC)
DS18S20F=(DS18S20 */ 461)+3200 'CALCULATE TEMP IN DEGREES F, NOT VALID FOR NEGATIVE TEMP
HSEROUT ["T", DEC (DS18S20F/100), ".", DEC1 (DS18S20F),"X"]
RETURN
ENDIF

IF COMMAND(0)="Q" THEN

LOW TEMP2 'initialize DS18S20
PAUSEUS 500 'wait for return pulse
TRISB.6=1 'set pin as input to get temp reading
PAUSEUS 100

IF TEMP2=1 THEN
DS18S20F=999 'VB error code signaling no sensor connected
HSEROUT ["Q", DEC (DS18S20F),"X"]
RETURN
ENDIF

PAUSEUS 400

'START TEMP READING
OWOUT TEMP2, 1, [$CC, $44] ' $CC-SKIP SEARCHING FOR MULTIPLE DS18S20, $44-START

WAITFORTEMP2:
OWIN TEMP2, 4, [COUNTR] 'CHECK FOR STILL BUSY CONVERTING SIGNAL
IF COUNTR=0 THEN WAITFORTEMP2

OWOUT TEMP2, 1, [$CC, $BE] 'READ THE TEMPERATURE
OWIN TEMP2, 0, [DS18S20.LOWBYTE, DS18S20.HIGHBYTE, SKIP 4, COUNTR, COUNTC]

DS18S20=((DS18S20>>1*100)-25)+(((COUNTC-COUNTR)*100)/COUNTC)
DS18S20F=(DS18S20 */ 461)+3200 'CALCULATE TEMP IN DEGREES F, NOT VALID FOR NEGATIVE TEMP
HSEROUT ["Q", DEC (DS18S20F/100), ".", DEC1 (DS18S20F),"X"]

ENDIF

RETURN

'END OF CODE

RETURN
ENDIF

Hello Friend...

A couple of things I saw that could give you problems...


Your ifs and END ifs... Some of your Ifs do NOT have a end if. I can't tell if you are only wanting to a *if* on just one line of code, or 5 lines...., but just below these missing end ifs, you *do* have a endif.


Then more importantly , 1/2 down your routine, you have the following:

RETURN
ENDIF


This means the return will NOT be excuted (to return to where your gosub was), *UNLESS* the if statement is true.

ENDIF should ALLLWAYs be before the return!




Here is a routine....I am not sure what you want to do with:

IF COMMAND(0)="T" THEN

LOW TEMP1 'initialize DS18S20
PAUSEUS 500 'wait for return pulse
TRISB.7=1 'set pin as input to get temp reading
PAUSEUS 100

IF TEMP1=1 THEN
DS18S20F=999 'VB error code signaling no sensor connected
HSEROUT ["T", DEC (DS18S20F),"X"]
RETURN
ENDIF


1. See that ENDIF after the return??? that is a killer!
2. When does your first IF statement end??? should it really be the following???? (

IF COMMAND(0)="T" THEN

LOW TEMP1 'initialize DS18S20
PAUSEUS 500 'wait for return pulse
TRISB.7=1 'set pin as input to get temp reading
PAUSEUS 100
ENDIF

IF TEMP1=1 THEN
DS18S20F=999 'VB error code signaling no sensor connected
HSEROUT ["T", DEC (DS18S20F),"X"]
ENDIF
RETURN


I see this in all your routines...


Dwayne

thanks, looks like I have multiple problems here. I'll re-work the code and clean up all the If-Endif and return statements and try it again.