Instant Interrupts - Revisited

[LinkMTech]

Hi everyone,
I think I'm getting very close to understanding DT's interrupt routine but need some direction.
I'm using a PIC16F688 to make myself a test fixture to test some product but pretty sure I did something wrong in the setups.
Using this small test program and a scope to monitor an output, I see the "Toggling" led stop during the interrupt routine. This only happens when PAUSE, FOR/NEXT and PAUSEUS is used in the main.
Ultimately, I will need to send serial data using SEROUT2 continueously in the background so I can do other chores in the foreground that will use TMR1, A/D and some simple LED indications.

'*************************************************************************
'*  Name    : Test fixture.BAS                                 
'*  Author  : Louis Chagoya                                     
'*  Notice  : Copyright (c) 2008 Link M Technologies            
'*          : All Rights Reserved                               
'*  Date    : 8/24/2009                                       
'*  Version : 1.1                                         
'*  Notes   : This system uses the PIC16F688 to learn DT's Interrupt system
'*  while utilizing other signalling functions at the same time.
'*************************************************************************
'/////////////////////////////////////////////////////////////////////////
'                       Configs
'/////////////////////////////////////////////////////////////////////////
@ __config _INTRC_OSC_NOCLKOUT & _WDT_OFF & _MCLRE_OFF & _CP_OFF
OSCCON = %01100001      ' Oscillator set to 4MHz, bits 6-4
CMCON0 = 7		        ' Analog comparators off
ADCON0 = %10010000      ' A/D right justified, Vref=VDD, AN2 selected
ADCON1 = %01010000      ' A/D conversion CLK/16
ANSEL = %00000100       ' AN2 set to analog input rest digital
TRISA = %00101101       ' Set ports 0,2,3 and 5 as inputs, rest outputs
TRISC = %00000000       ' Set all pins as outputs

'DEFINE OSC 8           ' Define OSC to 8Mhz for PAUSE setting
DEFINE ADC_BITS 10     ' ADCIN resolution  (Bits)
DEFINE ADC_CLOCK 5     ' ADC clock source  (Fosc/16)
DEFINE ADC_SAMPLEUS 7  ' ADC sampling time (uSec)
DEFINE SER2_BITS 8     ' Set up baud rate for 7812bps

'/////////////////////////////////////////////////////////////////////////
'                        Pin I/O naming
'/////////////////////////////////////////////////////////////////////////
Data_In VAR PORTA.0     ' Pin 13 Data from UUT
Data_Out VAR PORTA.1    ' Pin 12 Data to UUT
'        VAR PORTA.2    ' Pin 11 GPS input from UUT
Test VAR PORTA.3        ' Pin 4 Push button to begin test
Bypass VAR PORTA.4      ' Pin 3 Puts UUT into Bypass or Active mode
Byp_Sel VAR PORTA.5     ' Pin 2 Select type switch input
BCDval var PORTC        ' All of PortC declared as variable
Ready VAR PORTC.0       ' Pin 10 READY LED
Byp_Pass VAR PORTC.1    ' PIn 9 BYPASS test PASS LED - Green
Byp_Fail VAR PORTC.2    ' PIn 8 BYPASS test FAIL LED - Red
Act_Pass VAR PORTC.3    ' PIn 7 ACTIVE test PASS LED - Green
Act_Fail VAR PORTC.4    ' PIn 6 ACTIVE test FAIL LED - Red
Pwr_ON VAR PORTC.5      ' PIn 5 Provides power to UUT


'/////////////////////////////////////////////////////////////////////////
'                        Variable declarations
'/////////////////////////////////////////////////////////////////////////  
i VAR BYTE              ' Increment counter when needed
cksm VAR BYTE           ' Checksum variable


'/////////////////////////////////////////////////////////////////////////
'                       DT's Interrupt Routine
'/////////////////////////////////////////////////////////////////////////
INCLUDE "DT_INTS-14.bas"     ' Base Interrupt System
INCLUDE "ReEnterPBP.bas"     ' Include if using PBP interrupts

ASM
INT_LIST  macro    ; IntSource,        Label,  Type, ResetFlag?
        INT_Handler   TMR0_INT,    _Gen_Data,   PBP,  YES
    endm
    INT_CREATE               ; Creates the interrupt processor
ENDASM

'.....Various OPT_Reg tries....

'OPTION_REG.3 = 1             ' Prescaler is assigned to the WDT
'OPTION_REG.2 = 1             ' N/G, even with WDT ON
'OPTION_REG.1 = 1
'OPTION_REG.0 = 1             ; REGISTER 5-1: Prescaler = 1:1 via WDT rate

OPTION_REG = 7               ' Times out in 65.2ms. Will need 100ms when
                             ' get it to work
@ INT_ENABLE  TMR0_INT       ; enable Timer 0 interrupts

cksm = 85

'/////////////////////////////////////////////////////////////////////////
'                           Main Program
'/////////////////////////////////////////////////////////////////////////
start:     
     
     TOGGLE act_fail    ' Use this output to monitor routine
     PAUSE 1
     TOGGLE act_fail
     PAUSE 1
       
GOTO start

'---[TMR0 - interrupt handler]--------------------------------------------

Gen_Data:

    SEROUT2 Data_out, 108, [cksm]   ' Serial out cksm value at 7812bps
    PAUSEUS 3720                    ' Total time= 5ms

@ INT_RETURN


END

My understanding is that main program should not be disturbed by the interrupt routine if done properly. In this case, I'm hoping I'm not being proper rather than using the wrong PIC for my app.

Thank for your help...

[hatchethand1000]

Louie,

There are a couple of things I found while using Instant Ints. that may be worth looking at.
I am not an expert on them, I have found out what works for me by trial and error, and error and error as with all things Pic. But when you find the solution they work great!

When entering the interrupt, I stop additional interrupts from being serviced or re-serviced until I am ready to release control again.

INTCON needs to be set, looking at bits 7,6,5 and 2 page 15 and 45-47 of the data sheet.

INTCON = %111xx1xx      ' with x set for other functions and the 1's are a guess for your application

Code suggestion

'---[TMR0 - interrupt handler]--------------------------------------------

Gen_Data:
@ INT_DISABLE TMR0_INT
    SEROUT2 Data_out, 108, [cksm]   ' Serial out cksm value at 7812bps
    PAUSEUS 3720                    ' Total time= 5ms

@ INT_CLEAR TMR0_INT
@ INT_ENABLE TMR0_INT
@ INT_RETURN


END

Kevin

[Darrel Taylor]

Kevin,

You should NOT set INTCON, PIEx, PIRx, IPRx or any other interrupt related registers manually. DT_INTS handles all of those bits for you.

There is NO reason to INT_DISABLE / INT_ENABLE inside of an interrupt handler. Interrupts are automatically disabled by the hardware during an interrupt event, and can not cause another interrupt until the current one is finished. You are confusing things with ON INTERRUPT which must have DISABLE/ENABLE wrapped around them.

Louie,

When an interrupt occurs, the main program STOPS.
Program execution jumps to the ISR where it remains until the handlers have completed.
The main program will continue only after the entire ISR is finished.

The ISR and the main program do not execute at the same time.

It's why they're called Interrupts.
They Interrupt the main program to go do something else.
<br>

[hatchethand1000]

Darrel,

Thanks! I will modify my code, this will reduce overhead. Like I tried to say I do not know much about this, just enought to be dangerous and wrong most of the time.

I have been using the 16F688 and the 16F883 on a couple of projects, your routines work great.

When wanting to use the RBC_INT I found I had to set IOCB to get the interrupt to work on one input of PORTB.


Thanks,
Kevin

____________________

If you want the best seat in the house, you will have to move the Cat.

[LinkMTech]

Thanks for ending the misery Darrel.
I guess I was seeing too much into it. I still need to learn to juggle the events properly so they don't clash.
When I read the second post that says "Well, for one, this Blinky Light program will continue Blinking at the same rate, no matter what else you add to the Main: program loop. Try doing that with pauses.", it's true, but I made the mistake of assumming that the main program would go along like some absent minded fool without a bother in the world.


Thanks for all your contributions,

[Darrel Taylor]

Thanks for ending the misery Darrel.
I guess I was seeing too much into it.

Well don't end it there ...
It's probably that you're "not seeing enough into it".

Interrupts can definitely be used to make multiple things happen at the same time.
It's just that those things need to be happening in hardware.

If you want to send RS232 from an interrupt, then you should use the USART.
If you want to have an interrupt driven PAUSE, then use a Timer.

Jumping to the ISR and executing a software routine like serout(2) is not normally very productive, because the same routine could have been run from the main program without interrupts without much additional overhead. And since either way ... the program can't continue until the serout has completed, with or without interrupts makes little difference.

But if that interrupt uses the hardware USART, only a few instructions need to be executed to start the USART sending data, then it immediately returns from the interrupt and continues running the main program at the same time that the USART is sending the data.

There are several hardware peripherals on the various PIC's, and you might have 5 or 6 things all happening at the same time.

While software timed, bit-bang routines in your interrupts will occasionally be very useful ... avoid them at all cost.

Hardware and Interrupts make good companions.

hth,

[LinkMTech]

Well don't end it there ...

Alrighty then! Just when I was about to go with plan "B", add a PIC12F683 as a stand alone serial generator.
I just took a look at USART along with Mister E's PIC calculator and found that 7812 baud is configurable. A first glance some time ago gave me the impression that only common baud rates were available. I just recently discovered SEROUT2!
Is the USART hardware like the HPWM that can run continueously in the background?
If so, which commands will disrupt it or vice versa? I ran into some surprises when trying to use the HPWM while using the A/D in a WHILE:WEND. So went with PWM sprinkled through out the program along with a nice filter to hold my Vout.

The RS232 does not have to be interrupt started, just running all the time with the same 8x8 bytes of data. It will be processed and returned without any delay so I will have to act on it immediately.
Do you think this is still possible? Or go with plan "B"?

[Darrel Taylor]

I have been using the 16F688 and the 16F883 on a couple of projects, your routines work great.

Sweet!

When wanting to use the RBC_INT I found I had to set IOCB to get the interrupt to work on one input of PORTB.

Yes, you're correct.
I shouldn't have said "... or any other interrupt related registers manually". That was a little too broad.
There are several registers like IOCB that will need to be changed.

I probably should have limited it to ... "You should NOT set INTCON, PIEx, PIRx, IPRx". As those are the only interrupt bits that DT_INTS does handle for you.

Thanks for the correction.

If you want the best seat in the house, you will have to move the Cat.

Which is why the "best" seats in my house "belong" to the cats.
They know not to sit in mine ... they might get sat on.

[AndrewC]

You should NOT set INTCON, PIEx, PIRx, IPRx or any other interrupt related registers manually. DT_INTS handles all of those bits for you.

So where in D_INTS do you configure if you want to trigger off a rising or falling edge for something like INT0 ?

Thanks, Andrew

[Ioannis]

This is supposed to be done in the option register, isn't it?

DT-INTS are not for settings.

Ioannis

[AndrewC]

This is supposed to be done in the option register, isn't it?

DT-INTS are not for settings.

Ioannis

See my first post - Darrel says not to set the interrupt registers manually.

Andrew

[Ioannis]

This one you should set it yourself. Otherwise how would the system know what you want?

Ioannis