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larny
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Posted: 10:27am 18 Aug 2018

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I used MPLAB 8.92 to write & test a .asm programme for the 16F1708 PIC.

I chose that PIC as it has Interrupt on Change on all inputs.

I have found that IOC only works on PORTA inputs.
When I change one of the PORTC inputs, the IOCCF flag does not change & the PIC won't exit Sleep - as it does for PORTA inputs.

Is this due to a fault in the MPLAB software, or am I missing something?

Any assistance will be appreciated.

Len

Azure

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Posted: 11:41am 18 Aug 2018

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All 3 ports can be used for IOC. Master IOC needs to be enabled and every pin needs to have it's Interrupt on Positive and/or Negative edge enabled. The IOC flag for each pin are then used to determine which IOC pin caused the interrupt.

This is covered fairly well in Chapter 13 of the manual for the chip.

larny
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Posted: 12:01am 19 Aug 2018

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Thanks Azure. I had read chapter 13 & set IOCIE I also cleared ANSELA, B & C so the inputs are all digital.

So it appears to be a software fault in MPLAB. I understand that MPLAB 8.92 does not fully support the 16F1708, so I assume that is the issue.

I tried to use MPLABX but could not work out how to use it properly. So it looks as if I'll have to persevere with it & learn the ropes.
Len

Azure

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Posted: 12:20am 19 Aug 2018

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Have you set the IOC high or low enable flags for every pin on every port you want to create an IOC?

larny
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Posted: 01:35am 19 Aug 2018

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Azure said Have you set the IOC high or low enable flags for every pin on every port you want to create an IOC?

I believe so, but I'll be very grateful if you or someone else can find an error or omission. Here is the relevant part of the code.

Init
banksel TRISA ;selects BANK 1
movlw 0x38
movwf TRISA ;RA5:3 i/p - RA3 is MCLR & not used

clrf TRISB ;RB7:0 o/p
movlw 0xF8
movwf TRISC ;RC7:3 i/p

movlw 0x81 ;prescaler 1:4, internal clock
movwf OPTION_REG ;disable RB pull up resistors

banksel INLVLA ;selects Bank 7
movlw 0x30
movwf INLVLA ;RA5:4 set for Schmitt Trigger

movlw 0x30
movwf IOCAP ;RA5:4 set for positive edge change
clrf IOCAN ;RA5:4 negative edge change not used initially

movlw 0xF8
movwf IOCCP ;RC7:3 set for positive edge change
clrf IOCCN ;RC6:3 negative edge change not used initially

banksel ANSELA ;selects BANK 3
clrf ANSELA
clrf ANSELB
clrf ANSELC

banksel SLRCONA ;selects BANK 6
clrf SLRCONA
clrf SLRCONB
clrf SLRCONC

banksel WPUA ;selects BANK 4
clrf WPUA
clrf WPUB
clrf WPUC

banksel PORTA ;selects BANK 0
movlw 0x00 ;tempLC to be 0x07
movwf PORTA
movwf PORTC ;turn MOSFETs off

bsf INTCON, IOCIE ;bit 3 : awake on IOC
bsf INTCON, TMR0IE ;bit 5 : enable TMR0 overflow
return

Azure

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Posted: 04:45am 19 Aug 2018

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For setup:
Set TRISA/B/C for each IOC port pin to input
Set INLVLA/B/C threshold level for each IOC pin

Set IOCAP, IOCBP, IOCCP for each IOC positive edge
Set IOCAN, IOCBN, IOCCN for each IOC negative edge

After initial setup:
You need to enable INTCON bit 3 (interrupt on change enable) and bit 7 (global interrupt enable).

While program is running:
On an interrupt you can first check INTCON bit 0 to see if an interrupt on change has occurred on at least one interrupt on change pin.

Then Check each IOCAF, IOCBF, IOCCF to see which pin interrupted.

To clear interrupt that occurred:
Write to IOCAF, IOCBF, IOCCF after processing interrupt to clear flag.

In looking at your init routine there is no setting INTLVC or INTCON GIE (bit 7), I did not check if you preceeded any of these with the correct banksel.

larny
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Posted: 08:05am 19 Aug 2018

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Thanks Azure. See my comments in red below.

Azure said For setup:
Set TRISA/B/C for each IOC port pin to input I did that
Set INLVLA/B/C threshold level for each IOC pin As mentioned below, I neglected to set INVLC, but I doubt if it will make a difference. I'll check this later after I finish this post & let you know

Set IOCAP, IOCBP, IOCCP for each IOC positive edge I did that. Note that I'm not using PORTB
Set IOCAN, IOCBN, IOCCN for each IOC negative edge I did that

After initial setup:
You need to enable INTCON bit 3 (interrupt on change enable) and bit 7 (global interrupt enable). I set bit 3 but not bit 7 since I don't need an ISR.
All I want to do is to use IOC to exit from Sleep

While program is running:
On an interrupt you can first check INTCON bit 0 to see if an interrupt on change has occurred on at least one interrupt on change pin. I did not do it that way. To cut a long story short, I detect which input has changed in the Sub routines pp1 ~ 6.

Then Check each IOCAF, IOCBF, IOCCF to see which pin interrupted. As above I did not do it that way. I simply clear the flags on exit from Sleep

To clear interrupt that occurred:
Write to IOCAF, IOCBF, IOCCF after processing interrupt to clear flag. See my comment above

In looking at your init routine there is no setting INTLVC or INTCON GIE (bit 7), I did not check if you preceeded any of these with the correct banksel. Yes, you're right so I did that. As I said above I'm not using GIE I checked all of the banksels & all are correct,

Azure

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Posted: 02:53pm 19 Aug 2018

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OK, you should have mentioned in your first post that you are trying to wake from sleep and are not using interrupts.

You listed code does not set INTLVC so port C will default to ST mode.

You should also make sure to clear IOCAF and IOCCF before going to sleep.

If that does not work make sure you can read the IOCCF flag bits changing for each appropriate port C pin during normal operation (not in SLEEP).

larny
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Posted: 02:34am 20 Aug 2018

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Thanks Azure

Azure said OK, you should have mentioned in your first post that you are trying to wake from sleep and are not using interrupts. Sorry, I did not think of that since the PIC will awake from sleep without setting GIE.

You listed code does not set INTLVC so port C will default to ST mode. Someone on another forum mentioned this yesterday so I added INTLVC. I want it in the ST mode

You should also make sure to clear IOCAF and IOCCF before going to sleep.I clear them after exiting from sleep

If that does not work make sure you can read the IOCCF flag bits changing for each appropriate port C pin during normal operation (not in SLEEP).
The IOCCF never changes at any stage as you can see in the attachment.
I have to change PORTA to exit from sleep.

I'll programme it into a PIC & see if it works. If so, that will prove my presumption that the MBLAB software is faulty.

Azure

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Posted: 03:31am 20 Aug 2018

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Sorry I cannot read the text in the images they are too blurry.

You need to make sure the interrupt flags are cleared before you go to sleep, otherwise they will not sense a change and trigger the wake up.

I think you misunderstood my last point. As part of troubleshooting the problem you need to:
Make sure the connections to port C can be read and match the input on them;
Test them in both off and on states.

To do this you need to write some test code to make sure you can read port C pins while it is not asleep and see that input low and high signals are being read correctly. This is for testing your connections and setup of port C it would not be part of your normal code.

larny
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Posted: 04:28am 20 Aug 2018

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Thanks Azure.
I think I did understand your last point but you may a missed my point. The point I was trying to make is that the IOCCF is always 0 regardless of whether PORTC is changed in sleep or out of sleep. Whereas, the IOCAF changes as expected.

That's why I think it is a MPLAB software fault. I read somewhere that MPLAB 8.92 does not fully support this PIC.

See the attachments.

larny
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Posted: 05:25am 20 Aug 2018

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Azure
I did as you suggested in your last point. I inserted some nop statements. I changed PORTA at the first nop & PORTC at the second. The attachment shows the result. IOCAF changed, but not IOCCF.

I made them larger, so I hope you can read it this time.

Azure

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Posted: 07:25am 20 Aug 2018

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Are you doing this only as a software simulation or working with a real chip?

For the purpose of testing port C function you should not change any pin on Port A and just change a pin on port C to test it.

How are you clearing the flags?

larny
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Posted: 07:59am 20 Aug 2018

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Azure said Are you doing this only as a software simulation or working with a real chip?

For the purpose of testing port C function you should not change any pin on Port A and just change a pin on port C to test it.

How are you clearing the flags?

I'm simulating with MPLAB.
I did that - no difference. IOCCF Is still 0x00.

Here is the sub routine that clears the flags.

clr_flgs ;Clear flag(s) IOCAF & IOCCF
banksel IOCAF ;selects Bank 7
movlw 0xFF
xorwf IOCAF, w
andwf IOCAF, f ;this resets IOCAF - see spec p. 147

movlw 0xFF
xorwf IOCCF, w
andwf IOCCF, f ;this resets IOCCF - see spec p. 147

banksel PORTA ;selects Bank 0
return

matherp
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Posted: 08:28am 20 Aug 2018

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Quote I'm simulating with MPLAB.
I did that - no difference. IOCCF Is still 0x00.

IMHO you are expecting far too much of simulation. You have to test on the silicon to see if there is an issue.Edited by matherp 2018-08-21

larny
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Posted: 09:07am 20 Aug 2018

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matherp said

Quote I'm simulating with MPLAB.
I did that - no difference. IOCCF Is still 0x00.

IMHO you are expecting far too much of simulation. You have to test on the silicon to see if there is an issue.

Thanks for the comment matherp.
I have written many PIC programmes & tested them successfully in MPLAB before programming a PIC. So I don't see why it won't work in this case.

However, my next step is to programme a PIC & test.

By the way, what does IMHO mean?

LenEdited by larny 2018-08-21

Azure

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Posted: 09:44am 20 Aug 2018

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Quote By the way, what does IMHO mean?

In My Humble Opinion

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