ME Lab Trainer Timer1 Interrupt assistance needed

[LarryCardo]

9-1_Timer1_Interrupt rev A.pbp
I am trying to use the timer1 interrupt to determine the pulse width of a servo pulse (1 to 2 milliseconds). I plan to have about 10 servos and will need to refresh them every 20 milliseconds. Thus, I am hoping to use the interrupt so I do have to wait for the pulse to end.

I am using the ME Labs Trainer using the PIC16F1937 as a test bed. I cannot get the attached program to enter the interrupt handler. As timing is not critical, I figure I can use the ON INTERRUPT command.

Once I get this working, I will also use the interrupts to indicate the completion of the ADC conversion—that will eventually load the value to timer 1.

All suggestions would be appreciated.

Larry Cardo

[LarryCardo]

Not sure the attachment went thru? Here it is:

' microEngineering Labs Trainer-1 TIMER 1 UNTERRUPT TEST
' PLACE A HIGH ON porta.0 FOR THE TIME DECIDED BY TIMER ONE
'ON OVERFLOW FROM TIMER1 PLACE A LOW ON PORTA.0, BY USING INTERRUPT. THEN REPEAT.
' Target microcontroller: PIC16F1937
#CONFIG
; set CONFIG1 for internal oscillator
__config _CONFIG1, _FOSC_INTOSC
; set CONFIG2 for int osc pll controlled by OSCCON register,
;low-voltage programming on
__config _CONFIG2, _PLLEN_OFF & _LVP_ON
; see file PIC16F1937.INFO (in PBP installation) for more options
#ENDCONFIG
OSCCON = %01101000 ' Set internal osc to 4MHz with a 4x PLL disabled
DEFINE OSC 4 ' Tell PBP that the device will clock at 4MHz
ANSELA = %00000000 ' PortA all digital
PORTA = %00000000 ' Init all PORTA bits to low condition

ON INTERRUPT GOTO myint ' Interrupt handler is myint, enable interrupt-checking for lines below this point.
INTCON = %10110000 ' Enable GIE and RB0 interrupt

T1CON = %00110000 ' Enable Timer1 with prescale value 1:8
T1_IFLAG VAR PIR1.0 ' Give name to Timer1 interrupt flag in PIR1 register
SER VAR PORTA.0

T1_RUN VAR T1CON.0 ' Name the Timer1 Start/Stop control bit in T1CON register
LOW SER
' Attempt to use basic interrupt to time servo
'
mainloop:

If SER = 0 then 'next servo
gosub settimer
else
GOTO mainloop
Endif
GOTO mainloop

settimer:
HIGH SER 'start output to servo0
T1_RUN = 0 'STOP TIMER1
' Load timer1 with 0-255 lsb for time
TMR1L = -255 ' we do not know yet what time 255 will be
TMR1H = -200
T1_RUN = 1 ' START TIMER
'T1CON = %00110001 ' Start timer Enable Timer1 with prescale value 1:8
PIE1 = %10000001 ' enable timer1 overflow interrrupt
T1_IFLAG = 0
return

myint: 'INTERRUPT ROUTINE
DISABLE ' Disable interrupt-checking for all routines placed below this line.
T1_RUN = 0 'STOP TIMER
T1_IFLAG = 0 ' Clear Timer1 interrupt flag
LOW SER ' stop servo pulse
PORTA.1 = 1 'Did we enter interrupt handler? If so light LED
INTCON.1 = 0 ' Clear interrupt flag
INTCON = %10110000 ' Enable GIE and RB0 interrupt
RESUME ' Return to MAINLOOP program

[richard]

if you post code in code tags its much easier to interpret,ON INTERRUPT will probably never achieve your goal , use dt_ints

__config _CONFIG2, _PLLEN_OFF & _LVP_ON

LVP_ON can and will lead to unexpected mcu behaviour use LVP_OFF unless you know better

settimer: 
 HIGH SER 'start output to servo0 
 T1_RUN = 0 'STOP TIMER1
 ' Load timer1 with 0-255 lsb for time 
 TMR1L = -255 ' we do not know yet what time 255 will be 
 TMR1H = -200
 T1_RUN = 1 ' START TIMER
 'T1CON = %00110001 ' Start timer Enable Timer1 with prescale value 1:8 
[COLOR="red"] PIE1 = %10000001 ' enable timer1 overflow interrrupt[/COLOR]  ;this will not enable timer1 interrupt
[COLOR="blue"]needs to be
PIE1 = 1'
intcon.6=1;peie=1[/COLOR]  

 T1_IFLAG = 0
 return

pulsein would do a better job of measuring servo pulse width , your code does not sync timer with servo pulse nor does the interrupt routine differentiate which interrupt fired (int_int or tmr1_int). are you going to measure servo pulse width or the time between servo pulses ? is the sevo pulse active high or low ? . the variable latency using on_interrupt will lead to unavoidable inaccuracy also.

[LarryCardo]

Richard,

Thanks. I am not trying to measure a servo pulse width. I am trying to generate a active high pulse. The pulse length will hopefully be determined by the number I load into timer 1.

Not sure what code tags are, but I will research them. I heard about "DT_INTS" assembly interrupt program, but I'm lost with the simple basic routine.

Thanks for the LVP_off and PIE1 suggestions.

I will try these changes.

Much appreciated,

Larry

[richard]

I sure its been done before ,10 servos could be interesting (difficult) 8 would be relatively straight forward i think

i would have two timer interrupts


isr1 (every 2.5mS) giving a 2.5 window for each servo ;[ note 2.5 x 8 = 20mS == servo refresh rate]
set servo[x] output high (x=1-8)
preload isr2 timer with (64k-servo_time) duration
enable isr2


isr2 (set to the servo[x] period in uS) (@8mhz a 16 bit timer/with clk/2 input , preset to 65536- servo time in uS )
sets servo[x] output low
increment servo counter to next servo
disable isr2

[LarryCardo]

Richard,
Your sketch is similar to what I am intending. Rather than send out a pulse every 2.5 mS, I plan to send out a servo pulse to the next servo upon completion of the previous servo pulse. This method, I should be assured of being able to send to 10 servos, as each would not be at the max of 2.2mS--making a refresh rate variable, but less that 20 mS.

But I still cannot get the test program to output a high going pulse depending upon the value set in timer1??????

Thanks again for your thoughts. My current code is attached.

[richard]

this is what I was thinking

'****************************************************************
'*  Name    :servo.BAS                                      *
'*  Author  : [select VIEW...EDITOR OPTIONS]                    *
'*  Notice  : Copyright (c) 2016 [select VIEW...EDITOR OPTIONS] *
'*          : All Rights Reserved                               *
'*  Date    : 2/1/2016                                          *
'*  Version : 1.0                                               *
'*  Notes   :    pic16f1825                                               *
'*          :                                                   *
'****************************************************************
 
   
#CONFIG
             __config        _CONFIG1,    _FOSC_INTOSC & _CP_OFF & _WDTE_ON  &  _PWRTE_ON  &  _MCLRE_ON  & _CLKOUTEN_OFF
              __config      _CONFIG2, _PLLEN_ON & _LVP_OFF
#ENDCONFIG


DEFINE OSC 32
 
include "dt_ints-14.bas"
include "REENTERPBP.bas" 




asm
INT_LIST macro
      INT_Handler   TMR0_INT,   _serv,    PBP,  yes
      INT_Handler   TMR1_INT,   _st,      PBP,  yes
      endm
      INT_CREATE

ENDASM





  inc var bit
  buffer_dirty var bit
  buffer var word
  servo var byte
  servo_t var word[8]
  
@Timer1 = TMR1L ; map timer registers to a word variable
 Timer1 VAR WORD EXT 
 
 
 
   OSCCON=$70
   ANSELA=0
   ANSELC=0
   OPTION_REG=%11010110
  
   TRISA = %001110
   TRISC = 0        ' set PORTC I/O 
 
   porta.0=1
  
 clear
 
  latc=0
@ int_enable  TMR0_INT
@ int_enable  TMR0_INT
 servo=0
 pie1.0=1  
 servo_t[0]=500
 servo_t[1]=600
 servo_t[2]=700
 servo_t[3]=800
 servo_t[4]=900
 servo_t[5]=1000
 servo_t[6]=1200
 servo_t[7]=2000
 inc=0
 
 
main:
 pause 15
 if ! buffer_dirty then
 if inc then
 buffer=servo_t[0]-1
 else
 buffer=servo_t[0]+1
 endif
 if buffer > 2300 then
  inc=1
 elseif   buffer < 500  then
  inc=0
 endif 
 buffer_dirty =1
 endif

 
goto main 



serv:
tmr0=tmr0+100
latc.0[servo]=1
Timer1 = -servo_t[servo]
pir1.0=0
t1con=$31
@ int_return
 
 
st:
t1con=0
latc.0[servo]=0
servo= servo+1
if servo ==8 then   servo=0
if buffer_dirty then   
    servo_t[0]=buffer
   buffer_dirty=0
   endif
'    lata.4=!lata.4
'endif
@ int_return

it works quite well for 8 servo's.


I'm not sure about your plan the refresh time for each servo would then be variable and may cause issues . I thought that most servos expect a 20ms refresh rate .

I will try your code on a 16f1825

[richard]

some questions

INTCON = %10110000 ' Enable GIE and RB0 interrupt

why ?

you are enabling tmr0_int and int_int here and never using either

TMR1L = -255 ' we do not know yet what time 255 will be
TMR1H = -10

-10 is $f6 -255 = 1 therefore tmr1= 62977 ie about 65mS @4mhz pre scale =div 8
why ?

[richard]

sort of works now (moved output to portc to suit my setup)
set osc to 32mhz can't see any sense in snail-pace

''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
' Rev B--Using Richards suggestions 
'microEngineering Labs Trainer-1 TIMER 1 INTERRUPT TEST
' PLACE A HIGH ON porta.0 FOR THE TIME DECIDED BY TIMER ONE
'ON OVERFLOW FROM TIMER1 PLACE A LOW ON PORTA.0, BY USING INTERRUPT.  THEN REPEAT.
' Target microcontroller: PIC16F1937 
#CONFIG
             __config        _CONFIG1,    _FOSC_INTOSC & _CP_OFF & _WDTE_ON  &  _PWRTE_ON  &  _MCLRE_ON  & _CLKOUTEN_OFF
              __config      _CONFIG2, _PLLEN_ON & _LVP_OFF
#ENDCONFIG
 
OSCCON=$70 
DEFINE OSC 32 
 TRISA = %001110
   TRISC = 0   
ON INTERRUPT GOTO myint ' Interrupt handler is myint, enable interrupt-checking for lines below this point.
INTCON = %11000000 ' Enable GIE 
@Timer1 = TMR1L ; map timer registers to a word variable
 Timer1 VAR WORD EXT 
T1CON = %00110000 '  Enable Timer1 with prescale value 1:8    
T1_IFLAG VAR PIR1.0 ' Give name to Timer1 interrupt flag in PIR1 register
SER VAR PORTc.0

T1_RUN VAR T1CON.0 ' Name the Timer1 Start/Stop control bit in T1CON register
LOW SER 
' Attempt to use basic interrupt to time servo  
PIE1 = 1                                                                                              '
mainloop:

If SER = 0 then      'next servo   
      pauseus 2000
      gosub settimer
      PORTA.5=0
Endif
GOTO mainloop

settimer:        
    HIGH SER     'start output to servo0
    
    T1_RUN = 0  'STOP TIMER1
    
    Timer1=63535
    T1_RUN = 1    ' START TIMER        
    
    
   T1_IFLAG = 0  'Set Timer1 Interrupt flag to 0
return
   
 DISABLE
myint:  'INTERRUPT ROUTINE
    ' Disable interrupt-checking for all routines placed below this line.
    T1_RUN = 0    'STOP TIMER
       
    LOW SER             ' stop servo pulse 
     PORTA.5=1   'Did we enter interrupt handler?   If so light LED
      
   
RESUME ' Return to MAINLOOP program
enable

[LarryCardo]

Richard,
Thank you for the time you spent helping me “from down under”. Always wanted to visit your country and New Zealand, but at 75 the probability is looking slim. I wanted to tour your country on a motorcycle.

I took your tailored program and slightly modified it for my PIC16F1937 to get it to compile. The only significant changes were in the config files.

The scope pic is at 1 mS per division. The scope is looking at the output of PORTA.0 or the servo port. The freq of the positive pulse varies directly with the PAUSEUS command?

Changing the value of timer1 does not change the scope pic?

I like the way you removed unnecessary stuff.

I think we are close, but with no cigar.

Also attached is the “slightly modified” program. For some reason LVP will not run when set to off?

Larry

ps The number I placed in timer 1 was just a guess to see how it affected the output as I varied it. The unused instructions were a result of my lack of knowledge.

[richard]

TRISA = %001110

is incorrect for led to work should be TRISA = %111010

For some reason LVP will not run when set to off?

try this for config ,lvp_on will turn around and bite you eventually

#CONFIG
  __config  _CONFIG1, _FOSC_INTOSC & _WDTE_ON & _PWRTE_OFF & _MCLRE_ON & _CP_OFF & _CPD_OFF & _BOREN_ON & _CLKOUTEN_OFF & _IESO_ON & _FCMEN_ON
  __config  _CONFIG2, _WRT_OFF & _VCAPEN_OFF & _PLLEN_ON & _STVREN_ON & _BORV_19 & _LVP_OFF
#ENDCONFIG

tested and working , although I maintain the concept is flawed

''****************************************************************
'*  Name    : UNTITLED.BAS                                      *
'*  Author  : [select VIEW...EDITOR OPTIONS]                    *
'*  Notice  : Copyright (c) 2016 [select VIEW...EDITOR OPTIONS] *
'*          : All Rights Reserved                               *
'*  Date    : 2/15/2016                                         *
'*  Version : 1.0                                               *
'*  Notes   :                                                   *
'*          :                                                   *
'****************************************************************
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
' Rev B--Using Richards suggestions 
'microEngineering Labs Trainer-1 TIMER 1 INTERRUPT TEST
' PLACE A HIGH ON porta.0 FOR THE TIME DECIDED BY TIMER ONE
'ON OVERFLOW FROM TIMER1 PLACE A LOW ON PORTA.0, BY USING INTERRUPT.  THEN REPEAT.
' Target microcontroller: PIC16F1825 
#CONFIG
             __config        _CONFIG1,    _FOSC_INTOSC & _CP_OFF & _WDTE_ON  &  _PWRTE_ON  &  _MCLRE_ON  & _CLKOUTEN_OFF
              __config      _CONFIG2, _PLLEN_ON & _LVP_OFF

              
              
#ENDCONFIG
 
OSCCON=$70 
DEFINE OSC 32 
 TRISA = %111010
   TRISC = 0   
ON INTERRUPT GOTO myint ' Interrupt handler is myint, enable interrupt-checking for lines below this point.
INTCON = %11000000 ' Enable GIE 
@Timer1 = TMR1L ; map timer registers to a word variable
 Timer1 VAR WORD EXT 
  
T1_IFLAG VAR PIR1.0 ' Give name to Timer1 interrupt flag in PIR1 register
SER VAR PORTA.0
T1CON=0
'
LOW SER 
' Attempt to use basic interrupt to time servo  
PIE1 = 1                                                                                              '
T1_IFLAG =1

mainloop:
If T1_IFLAG then      'next servo
      pauseus 500
      T1_IFLAG = 0  'Set Timer1 Interrupt flag to 0
      PORTA.2=0
      gosub settimer
Endif      

GOTO mainloop

settimer:        
    HIGH SER     'start output to servo0      
            
    Timer1=64535 
    
    T1CON=$31 ' START TIMER  
return   
   

   
 DISABLE
myint:  'INTERRUPT ROUTINE
    ' Disable interrupt-checking for all routines placed below this line.
    T1CON=0    'STOP TIMER           
    LOW SER             ' stop servo pulse 
     PORTA.2=1   'Did we enter interrupt handler?   If so light LED
      
    
RESUME ' Return to MAINLOOP program
enable

[richard]

just noticed you are using a ME Labs Trainer , a device I know nothing about . There is a good chance it actually employs low voltage programming . the docs should have a sample config section in them somewhere it would be best to use one of them.

[LarryCardo]

Thanks again Richard,

Using your revised config settings and they are working except for LVP_OFF. For the trainer it needs to be on.

Still working on some weird syntax errors with TRISA AND TRISC??? and "SER VAR PORTA.0 " is saying bad date type??

Playing with the previous revision, I found the pulse on PORTA.0 does not change with the value set in Timer 1. But does change with pauseus. If I rem out pauseus, the scope shows a square wave of a period of 5us.

Will continue to work on the weird syntax errors.

Larry

[richard]

IF you have any appreciable load on the outputs ie a led with too small a series resistor
then you will have rmw issues

code to avoid rmw and demo variable servo pulse

'****************************************************************
'*  Name    : UNTITLED.BAS                                      *
'*  Author  : [select VIEW...EDITOR OPTIONS]                    *
'*  Notice  : Copyright (c) 2016 [select VIEW...EDITOR OPTIONS] *
'*          : All Rights Reserved                               *
'*  Date    : 2/15/2016                                         *
'*  Version : 1.0                                               *
'*  Notes   :                                                   *
'*          :                                                   *
'****************************************************************
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
' Rev B--Using Richards suggestions 
'microEngineering Labs Trainer-1 TIMER 1 INTERRUPT TEST
' PLACE A HIGH ON porta.0 FOR THE TIME DECIDED BY TIMER ONE
'ON OVERFLOW FROM TIMER1 PLACE A LOW ON PORTA.0, BY USING INTERRUPT.  THEN REPEAT.
' Target microcontroller: PIC16F1825 
#CONFIG
             __config        _CONFIG1,    _FOSC_INTOSC & _CP_OFF & _WDTE_ON  &  _PWRTE_ON  &  _MCLRE_ON  & _CLKOUTEN_OFF
              __config      _CONFIG2, _PLLEN_ON & _LVP_OFF

              
              
#ENDCONFIG
 
OSCCON=$70 
DEFINE OSC 32

 
 TRISA = %111010
 TRISC = 0  
 
  
ON INTERRUPT GOTO myint ' Interrupt handler is myint, enable interrupt-checking for lines below this point.
INTCON = %11000000 ' Enable GIE PEIE 
@Timer1 = TMR1L ; map timer registers to a word variable


 Timer1 VAR WORD EXT 
 servo_t  VAR WORD
 INC VAR    BIT
 
 
 
 
T1_IFLAG VAR PIR1.0 ' Give name to Timer1 interrupt flag in PIR1 register
SER VAR LATA.0

INC=0
LOW SER
T1CON=0
PIE1 = 1                                                                                              '
T1_IFLAG =1
 servo_t=500

mainloop:
If T1_IFLAG then      'next servo
      pauseus 500
      T1_IFLAG = 0  'Set Timer1 Interrupt flag to 0
      
      gosub settimer
      if inc then
        servo_t=servo_t-200
      else
        servo_t=servo_t+200
      endif
     if servo_t > 2100 then
        inc=1
        LATA.2=1
     elseif   servo_t< 500  then
        inc=0
        LATA.2=0
     endif 
Endif      

GOTO mainloop

settimer:        
    SER=1     'start output to servo0      
            
    Timer1=  - servo_t 
    
    T1CON=$31 ' START TIMER  
return   
   

   
 DISABLE
myint:  'INTERRUPT ROUTINE
    ' Disable interrupt-checking for all routines placed below this line.
    T1CON=0    'STOP TIMER           
    SER =0            ' stop servo pulse 
       
      
    
RESUME ' Return to MAINLOOP program
enable

[LarryCardo]

Hi Richard,

I am a little disappointed relative to the difficulty is programming a simple interrupt. Life should not be this difficult. Taking a brief break. Also looking at the assemble program DT_.

Thanks,

Larry