Time Out ?

[tazntex]

I've compiled and ran this but it still hangs meaning the output is still on then a few seconds later goes off. As I noted PORTA needs to be cleared but with the exception of PORTA.0 ( my serin pin). By adding clrf PORTB for a split second they come on and go off immediately while still transmitting. I wonder if if by timing out after receiving is causing PORTB to now act that way. Is this to fast "at 4MHz Timer1 overflows in 65536 * 1uS (~65.5mS)" ? and how could I adjust this?


@ DEVICE PIC16F628a,XT_OSC
@ DEVICE pic16F628a, WDT_OFF
@ DEVICE pic16F628a, PWRT_ON
@ DEVICE pic16F628a, MCLR_ON
@ DEVICE pic16F628a, BOD_ON
@ DEVICE pic16F628a, LVP_OFF
@ DEVICE pic16F628a, CPD_OFF
@ DEVICE pic16F628a, PROTECT_OFF

DEFINE OSC 4
DEFINE NO_CLRWDT 1 ' Watchdog timer is disabled, so we don't need to reset it
DEFINE INTHAND RESET_VT ' Interrrupt on Timer1 overflow to reset outputs in 65.5mS
' if no serial data received in this time period

TMR1IF var PIR1.0 ' Timer1 overflow interrupt flag (reset in int handler)
TMR1IE var PIE1.0 ' Timer1 interrupt enable bit
CMCON=%00000111
vrcon=0
trisa = %00000001
trisb = %00000000
PORTA = 0
PORTB = 0
serpin VAR porta.0 'serial input pin
address con %0010000000000001
add1 VAR WORD
address1 var byte
address2 var byte
address3 var byte
address4 var byte
addA var byte '0-7
addB var byte '8-15
addC var byte '0-7
addD var byte '8-15
chkcrc var byte
crcA var byte
crcB var byte
chksum2 var byte bank0 system
chksum3 var byte
i var byte
mydata var byte
mydata1 VAR byte
mydata2 var byte
mydata3 var byte
mydata4 var byte
rf var porta.4

'Variables for saving state in interrupt handler
wsave VAR BYTE $70 system ' Saves W
ssave VAR BYTE bank0 system ' Saves STATUS
psave VAR BYTE bank0 system ' Saves PCLATH
fsave VAR BYTE bank0 system ' Saves FSR

' Setup Timer1 for resets after ~65.5mS
T1CON = %00000000 ' Internal clock, 1:1 prescale, Timer1 off for now
TMR1L = 0
TMR1H = 0 ' Timer1 low & high bytes cleared
TMR1IF = 0 ' Clear Timer1 overflow flag before enabling interrupt
TMR1IE = 1 ' Enable Timer1 overflow interrupt
INTCON = %11000000 ' Global & peripheral ints enabled
chksum2 = 0 ' Clear match count
GOTO cycle ' Jump over int handler

ASM
RESET_VT
movwf wsave ; Save W
swapf STATUS, W ; Swap STATUS to W (swap avoids changing STATUS)
clrf STATUS ; Clear STATUS
movwf ssave ; Save swapped STATUS
movf PCLATH, W ; Move PCLATH to W
movwf psave ; Save PCLATH
movf FSR, W ; Move FSR to W
movwf fsave ; Save FSR

; Do interrupt stuff here
bcf T1CON,TMR1ON ; Stop Timer1
clrf TMR1L ; Clear low byte
clrf TMR1H ; Clear high byte
bcf PIR1,TMR1IF ; Clear Timer1 interrupt flag bit
;clrf GPIO ; Clear outputs on button release (or timeout)
;clrf PORTA ; Clear outputs on button release (or timeout)

From what I understand from the datasheet I can clear selected outputs by:
bcf PORTA, 2
bcf PORTA, 3
bcf PORTB, 0
bcf PORTB, 1
bcf PORTB, 2
bcf PORTB, 3
bcf PORTB, 4
bcf PORTB, 5
bcf PORTB, 6
bcf PORTB, 7

;I REALLY NEED TO CLEAR PORTA WITH THE EXCEPTION OF PORTA.O (SERIN PORT)

clrf PORTB ; Clear outputs on button release (or timeout)
clrf chksum2 ; Clear match variable

; Restore FSR, PCLATH, STATUS and W registers
movf fsave, W ; retrieve FSR value
movwf FSR ; Restore it to FSR
movf psave, W ; Retrieve PCLATH value
movwf PCLATH ; Restore it to PCLATH
swapf ssave, W ; Get swapped STATUS value (swap to avoid changing STATUS)
movwf STATUS ; Restore it to STATUS
swapf wsave, F ; Swap the stored W value
swapf wsave, W ; Restore it to W (swap to avoid changing STATUS)
bsf T1CON,TMR1ON ; Re-enable Timer1 before exiting interrupt handler
retfie ; Return from the interrupt
ENDASM

PAUSE 1000 'SETTLE INPUTS


start:
high rf
'ZERO VARIABLES
ADD1=0
adda = 0
addb = 0
addc = 0
addd = 0
address1 = 0
address2 = 0
address3 = 0
address4 = 0
mydata=0
chkcrc = 0
i = 0
mydata = 0
mydata1 = 0
mydata2 = 0
mydata3 = 0
mydata4 = 0
porta.1 = 0
porta.2 = 0
porta.3 = 0
portb = 0
pause 50

cycle:
high rf
repeat
ADD1=0
adda = 0
addb = 0
addc = 0
addd = 0
address1 = 0
address2 = 0
address3 = 0
address4 = 0
chkcrc = 0
i = 0
mydata = 0
mydata1 = 0
mydata2 = 0
mydata3 = 0
mydata4 = 0

'************************************************* *****************************
' Fire up Timer1 before entry to serial input routine
T1CON.0 = 1

' at 4MHz Timer1 overflows in 65536 * 1uS (~65.5mS) if no Synch byte
' and serial data arrive on time. SERIN2 timeout & label options
' are useless with a noisy RF receiver output - as noise continually
' resets the timeout period causing it to hang forever.

' Wait for Synch byte, then get new inbound data & checksum
SERIN2 serpin,16468,[wait(254),address1,address2,address3,address4,_
mydata1,mydata2,crca,crcb]

T1CON.0 = 0 ' Stop Timer1 once we've received data
TMR1L = 0 ' Clear low byte
TMR1H = 0 ' Clear high byte

' / **** Begin data validation **** /

As I mentioned earlier after making changes the output will quickly come on and go off.
Thanks

[tazntex]

Looking at the datasheet I just changed the timer from Internal to External :
from this:
' Setup Timer1 for resets after ~65.5mS
T1CON = %00000000'%00000000Internal clock, 1:1 prescale, Timer1 off for now

to this:
' Setup Timer1 for resets after ~65.5mS
T1CON = %00000010'%00000000Internal clock, 1:1 prescale, Timer1 off for now

Now it works and holds the output on while transmitting but when I release the button most of the time there is a delay of several seconds before the output goes off.

Am I on the right track?

[mackrackit]

I did not think about the external OSC change, good catch.

For some reason I was thinking that you did not want to clear anything in the ASM routine...
I do not see what it would hurt to clear all of PORTA in the ASM, "clrf PORTA". When the code gets to SERIN2 it will still input.

Now it works and holds the output on while transmitting but when I release the button most of the time there is a delay of several seconds before the output goes off.

That I am not sure about. Maybe there is something in the TX code causing things to drag?

Maybe post both the TX and RX and someone will be able to spot the problem.

[tazntex]

Am Using the correct timer, I am using an external 4mHz oscilliator on RA6 and RA7, I've just noticed that on the original code Bruce has the PIC is a 12F635. T1CON: TIMER1 CONTROL REGISTER bit 7 is set to 0 and that Timer counts when the gate is low, I don't have a gate, so how am I counting?


By the way I am using a 16F628A.
Thanks

[mackrackit]

Neither on is counting.
On the 635, T1CON bit 6 is 0 in Bruce's code. Bit 6 being 0 just turns on the timer, no gate.

[tazntex]

Thanks for the reply, So as it is in the previous post it seems to work, but I just was looking over the datasheets of both the PIC's this past weekend. I was just curious how it works, I am still struggling to understand the timers. I shall keep reading because it is not clear to me what makes it "tick" to jump out and continue.


Thanks again for the many replies.
'73

[mackrackit]

I shall keep reading because it is not clear to me what makes it "tick" to jump out and continue.

Yup, they can be confusing at times. You may have this part figured out but we will start someplace.

Once the timer is setup it will run in the background as if there is a second chip. This second process can be looked at as an alarm clock. When the alarm goes off, timer overflows, it will interrupt the main process.

At this time we turn the alarm off, disable the timer, and do whatever... get up go about our day....

Then the alarm is set again...