Strange problem with 'pauseus' command

[andywpg]

I am having a weird problem here, and I'm wondering if someone has any idea
what's going on. I'm building a new version of my charcoal smoker temperature
controller, and decided to incorporate a damper on the airbox. That way, when it wants
to cool off the smoker, the damper closes and it cools off quicker.

I decided to use an R/C servo to control the damper, that way it is easy to adjust the
open / close points. Rather than have my main processor (18F2550) control the servo, I
decided to use a 12F683 and just have a line from the main processor that goes high or low.
This way, the main processor doesn't have to worry about creating the pulse that controls
the servo.

I only need the servo all the way one way (1mS pulse) or the other (2mS pulse), no proportional
control is needed.

Below is the original way I wrote the code. The numbers for pulse count and pulse
are what worked out to the two pulse lengths and the 20mS period. It worked fine.

I wanted to have a little more resolution for adjustments, so I decided to change the 100uS
pause to 50uS and double the other three numbers. When I looked at the signal on the scope,
it was nowhere near what I wanted. In fact, I had to lower the three numbers almost to
where they were in the original!

Is 50uS just too fast for 8Mhz? If not, what else could have caused this effect?

#CONFIG
    __config _INTRC_OSC_NOCLKOUT & _WDT_OFF & _MCLRE_ON & _CP_OFF
#ENDCONFIG

DEFINE OSC 8 'LETS PBP KNOW WE WILL BE RUNNING AT 8MHZ

DISABLE 'NO DEBUG, NO INTERRUPTS

'PIN DEFENITIONS
'GP0 USED FOR ICSP DATA
'GP1 USED FOR ICSP CLOCK
'GP2 USED TO DRIVE SERVO (SIGNAL LINE)
'GP3 USED FOR MCLR AND ICSP PROGRAMMING
'GP4 USED FOR TRIGGER INPUT
'GP5 USED FOR LED

'SET UP THE SPECIAL REGISTERS
OSCCON = %01110001  '8MHZ INTERNAL CLOCK USED
CMCON0 = %00000111 'CIN PINS ARE I/O, COUT PIN IS I/O
OPTION_REG = 0 'WEAK PULL UPS ARE ENABLED
TRISIO = %00011011 'GP5 AND GP2 ARE OUTPUTS, THE REST ARE INPUTS 
ANSEL = 0 'NO ANALOG PORTS - ALL DIGITAL
WPU = %00010000 'GP4 WEAK PULL UP ENABLED. GP3 WEAK PULL UP AUTOMATICALLY ENABLED
				'AS THE PIN IS DEFINED AS MCLR
IOC = 0 'NO INTERRUPT ON CHANGE

'PIN ALIASES
SERVO VAR GPIO.2
TRIGGER VAR GPIO.4
LED VAR GPIO.5
                                                                                              
'VARIABLES                                                                                     
PERIOD_COUNT VAR BYTE 'TO TIME THE 20mS PERIOD
PULSE VAR BYTE 'PULSE LENGTH IN 100uS INCREMENTS
                                                                                               
SERVO = 0 'MAKE SURE NO SIGNAL                                                                                
LED = 0 'MAKE SURE LED IS OFF
                                                                                               
MAIN:
	DO 'ENDLESS LOOP
		IF TRIGGER = 1 THEN 'CLOSE THE DAMPER
			PULSE = 19 '2.0mS PULSE TO SERVO
			LED = 1 'TURN ON LED
		ELSE 'OPEN THE DAMPER 
			PULSE = 8 '1.0mS PULSE TO SERVO
			LED = 0 'TURN OFF LED
		ENDIF
		FOR PERIOD_COUNT = 1 TO 187 '20mS PERIOD
			IF PERIOD_COUNT > PULSE THEN 'MAKE LINE LOW FOR REST OF 20mS PERIOD
				SERVO = 0 'MAKE SURE SERVO SIGNAL IS NOW LOW
			ELSE
				SERVO = 1 'SERVO SIGNAL LINE HIGH FOR 1.0 OR 2.0mS			
			ENDIF
			PAUSEUS 100 '100uS PAUSE		
        NEXT PERIOD_COUNT                                                                            
    LOOP                                                                                       
END

[richard]

PERIOD_COUNT VAR BYTE 'TO TIME THE 20mS PERIOD

I wanted to have a little more resolution for adjustments, so I decided to change the 100uS
pause to 50uS and double the other three numbers

PERIOD_COUNT = 1 TO 187 '20mS PERIOD

what is 187*2 ?
will it fit in a byte ?

[andywpg]

what is 187*2 ?
will it fit in a byte ?

Sorry, forgot to mention that I did define PERIOD_COUNT as a word when I doubled everything.

Thanks,

Andy

[richard]

FOR PERIOD_COUNT = 1 TO 187 '20mS PERIOD
			IF PERIOD_COUNT > PULSE THEN 'MAKE LINE LOW FOR REST OF 20mS PERIOD
				SERVO = 0 'MAKE SURE SERVO SIGNAL IS NOW LOW
			ELSE
				SERVO = 1 'SERVO SIGNAL LINE HIGH FOR 1.0 OR 2.0mS			
			ENDIF
					
        NEXT PERIOD_COUNT

this for next loop takes 45us to execute when PERIOD_COUNT is a word var even without the pause, it severly limits resolution


if you do it this way the resolution is 1 uS or thereabouts

'****************************************************************
'*  Name    : hobby_servo.BAS                                   *
'*  Author  : richard                                           *
'*  Notice  : Copyright (c) 2016 [select VIEW...EDITOR OPTIONS] *
'*          : All Rights Reserved                               *
'*  Date    : 11/19/2016                                        *
'*  Version : 1.0                                               *
'*  Notes   : 12f683                                            *
'*          :                                                   *
'****************************************************************
#CONFIG
    __config _INTRC_OSC_NOCLKOUT & _WDT_OFF & _MCLRE_ON & _CP_OFF
#ENDCONFIG
DEFINE OSC 8 'LETS PBP KNOW WE WILL BE RUNNING AT 8MHZ
include "dt_ints-14.bas"
include "REENTERPBP.bas" 

'PIN DEFENITIONS
'GP2 USED TO DRIVE SERVO (SIGNAL LINE)
'GP3 USED FOR MCLR AND ICSP PROGRAMMING
'GP4 USED FOR TRIGGER INPUT
'GP5 USED FOR LED
'SET UP THE  REGISTERS
OSCCON = %01110001  '8MHZ INTERNAL CLOCK USED
CMCON0 = %00000111 'CIN PINS ARE I/O, COUT PIN IS I/O
OPTION_REG=%01010111      ;set prescaler and assign it to tmr0
define NO_WDT 1
TRISIO = %00011011 'GP5 AND GP2 ARE OUTPUTS, THE REST ARE INPUTS 
ANSEL = 0 'NO ANALOG PORTS - ALL DIGITAL
WPU = %00010000 'GP4 WEAK PULL UP ENABLED. GP3 WEAK PULL UP AUTOMATICALLY ENABLED
    'AS THE PIN IS DEFINED AS MCLR
@Timer1 = TMR1L ; map timer1 registers to a word variable
Timer1 VAR WORD EXT 
t1con=0
  
wsave   VAR BYTE    $20     SYSTEM      ' location for W if in bank0
;wsave   VAR BYTE    $70     SYSTEM      ' alternate save location for W 
                                         ' if using $70, comment wsave1-3
' --- IF any of these three lines cause an error ?? ------------------------
'       Comment them out to fix the problem ----
' -- Which variables are needed, depends on the Chip you are using -- 
wsave1  VAR BYTE    $A0     SYSTEM      ' location for W if in bank1
'wsave2  VAR BYTE    $120    SYSTEM      ' location for W if in bank2
'Wsave3  VAR BYTE    $1A0    SYSTEM      ' location for W if in bank3
' --------------------------------------------------------------------------
 
 
 

asm
INT_LIST macro
      INT_Handler   TMR0_INT,   _serv,    PBP,  yes
      INT_Handler   TMR1_INT,   _st,      PBP,  yes
      endm
      INT_CREATE
ENDASM 
'PIN ALIASES
SERVO VAR GPIO.2
TRIGGER VAR GPIO.4
LED VAR GPIO.5
                                                                                              
'VARIABLES                                                                                     
servo_t VAR word 'pulse TIME  in us
                                                                                               
SERVO = 0 'MAKE SURE NO SIGNAL                                                                                
LED = 0 'MAKE SURE LED IS OFF
@ int_enable  TMR0_INT
@ int_enable  TMR1_INT                                                                                               
MAIN:
  IF TRIGGER = 1 THEN 'CLOSE THE DAMPER
   servo_t = 2000 '2.0mS PULSE TO SERVO
   LED = 1 'TURN ON LED
  ELSE 'OPEN THE DAMPER 
   servo_t = 1000'1.0mS PULSE TO SERVO
   LED = 0 'TURN OFF LED
  ENDIF
 goto main                                                                                  
END
 
serv:
tmr0=tmr0+100

Timer1 = -servo_t
pir1.0=0
t1con=$11
SERVO =1 
   
@ int_return
 
 
st:
t1con=0
servo=0
@ int_return

[andywpg]

'************************************************* ***************
'* Name : hobby_servo.BAS *
'* Author : richard *
'* Notice : Copyright (c) 2016 [select VIEW...EDITOR OPTIONS] *
'* : All Rights Reserved *
'* Date : 11/19/2016 *
'* Version : 1.0 *
'* Notes : 12f683 *
'* : *
'************************************************* ***************

I thank you Sir. MUCH better resolution, like you said. While I have used DT's Instant Interrupts a little,
I have not used them a lot. I'm starting to get a handle on how you did that. In fact, I may port this over
to an 18F2550 so I can use debug to watch everything to help my understanding.

Thanks again,

Andy

[richard]

I may port this over
to an 18F2550 so I can use debug to watch everything to help my understanding.

it should be pretty straight forward to get it to work on a pic18.
trying to debug/watch isr's in action is an art form in itself especially when they need to run at full speed to function realistically or even at all.

try this version if you want to regulate the speed the servo

ps the osctune setting is for my particular chip others may/will need a different value ,see data sheet
I chose a value that gives me an accurate 2mS pulse for a servo_t value of 2000 / trial and error

'****************************************************************
'*  Name    : hobby_servo.BAS                                   *
'*  Author  : richard                                           *
'*  Notice  : Copyright (c) 2016 [select VIEW...EDITOR OPTIONS] *
'*          : All Rights Reserved                               *
'*  Date    : 11/19/2016                                        *
'*  Version : 1.0                                               *
'*  Notes   : 12f683                                            *
'*          : now with speed control and osc tuned for accuracy *
'****************************************************************
#CONFIG
    __config _INTRC_OSC_NOCLKOUT & _WDT_OFF & _MCLRE_OFF & _CP_OFF
#ENDCONFIG
DEFINE OSC 8 'LETS PBP KNOW WE WILL BE RUNNING AT 8MHZ
include "dt_ints-14.bas"
include "REENTERPBP.bas" 

'PIN DEFENITIONS
'GP2 USED TO DRIVE SERVO (SIGNAL LINE)
'GP3/mclr  USED FOR TRIGGER INPUT
'GP4 vacant
'GP5 USED FOR LED
'SET UP THE  REGISTERS
OSCCON = %01110001  '8MHZ INTERNAL CLOCK USED
CMCON0 = %00000111 'CIN PINS ARE I/O, COUT PIN IS I/O
OPTION_REG=%01010111      ;set prescaler and assign it to tmr0
define NO_WDT 1
TRISIO = %00011011 'GP5 AND GP2 ARE OUTPUTS, THE REST ARE INPUTS 
ANSEL = 0 'NO ANALOG PORTS - ALL DIGITAL
WPU = %00010000 'GP4 WEAK PULL UP ENABLED. GP3 WEAK PULL UP AUTOMATICALLY ENABLED
    'AS THE PIN IS DEFINED AS MCLR
@Timer1 = TMR1L ; map timer1 registers to a word variable
Timer1 VAR WORD EXT 
t1con=0
OSCTUNE=3  ;trim best way
closed   con 2000
open     con 500
wsave   VAR BYTE    $20     SYSTEM      ' location for W if in bank0
;wsave   VAR BYTE    $70     SYSTEM      ' alternate save location for W 
                                         ' if using $70, comment wsave1-3
' --- IF any of these three lines cause an error ?? ------------------------
'       Comment them out to fix the problem ----
' -- Which variables are needed, depends on the Chip you are using -- 
wsave1  VAR BYTE    $A0     SYSTEM      ' location for W if in bank1
'wsave2  VAR BYTE    $120    SYSTEM      ' location for W if in bank2
'Wsave3  VAR BYTE    $1A0    SYSTEM      ' location for W if in bank3
' --------------------------------------------------------------------------
asm
INT_LIST macro
      INT_Handler   TMR0_INT,   _serv,    PBP,  yes
      INT_Handler   TMR1_INT,   _st,      PBP,  yes
      endm
      INT_CREATE
ENDASM 
'PIN ALIASES
SERVO VAR GPIO.2
TRIGGER VAR GPIO.3
LED VAR GPIO.5
                                                                                              
'VARIABLES                                                                                     
servo_t VAR word 'pulse TIME  in us
tick var byte
mvflg var bit 
                                                                                              
servo_t=open                                                                              
LED = !TRIGGER  
@ int_enable  TMR0_INT
@ int_enable  TMR1_INT                                                                                               
MAIN:
  IF TRIGGER = 1 THEN 'CLOSE THE DAMPER
      LED = 1 'TURN ON LED
      while  servo_t < closed 
       servo_t = servo_t + 20
       mvflg=0
       while  !mvflg  :wend
      wend
      servo_t =  closed
  ELSE 'OPEN THE DAMPER  
   LED = 0 'TURN ON LED
      while  servo_t > open 
       servo_t = servo_t - 20
       mvflg=0
       while  !mvflg  :wend
      wend
      servo_t =  open
  ENDIF
 goto main                                                                                  
END

serv:
tmr0=tmr0+97
Timer1 = ~servo_t;+50    alternative trim method
pir1.0=0
t1con=$11
SERVO =1 
tick=tick+1
if tick.0 then mvflg=1
@ int_return
 
st:
t1con=0
servo=0
@ int_return