Instant Interrupts - Revisited

[Darrel Taylor]

Damir,

I can duplicate the issue here, which appears to be the old R-M-W hardware problem.
I moved the PWMs over to PORTC, and everything works fine.

Since I2C uses pull-ups instead of bi-polar driven outputs, it's more susceptable to R-M-W problems.

If you cannot move pins around on your project, you can get away with the following.
In general, I do not recommend doing this type of modification.
But in your specific case, it should work.

  SPWM_LIST macro 
      SPWM_PIN LATA, 2, _CH1 
      SPWM_PIN LATA, 3, _CH2 
      SPWM_PIN LATA, 4, _CH3 
      SPWM_PIN LATA, 5, _CH4 
    endm

[Darrel Taylor]

I should have also mentioned that when using the LATA register, you'll need to set the pins to output manually.

TRISA = %11000011

[DaTiNs]

Thank you very much!

I must add TRISA = 0 to the begin of code, and then start work great.

One more time, thank you, Damir.

[SteveB]

Darrel,
While poking around and getting ideas, I got to looking at ver 1.2 of "Elapsed_INT-18.bas". I was particularly interested in the nice routine to calculate the timer reload constant:

' -------------- calc timer reload Constants -------------------------------
ASM
T1PS = 1                             ; start with 1:1 postscaler
TimerConst = ((OSC*1000000)/4/100)   ; how many timer ticks will it take
  while TimerConst > 65400           ; if it's more than the timer can count
T1PS = T1PS * 2                      ;   double the postscaler
TimerConst = TimerConst / 2          ;   halve the count
  endw
TimerConst = 65536 - TimerConst + 8  ; final reload value

But, I think there is an error in the formula. The absolute time it takes to execute the 8 instruction cycles doesn’t change. But, the time in relation to the TMR1L will be proportional to the prescaler. So, that should be accounted for in the formula, as such:

TimerConst = 65536 - TimerConst + (8/T1PS)  ; final reload value

Since it's not likely the prescaler will need to be above 1:8, the 8/T1PS shouldn’t get too low.

Thanks again for your great work and inspiring examples,
Steve

[SteveB]

The code could also be changed thus, not that it makes a difference:

T1PS = 1                             ; start with 1:1 postscaler
TimerConst = ((OSC*1000000)/4/100)+8 ; how many timer ticks will it take
  while TimerConst > 65400           ; if it's more than the timer can count
T1PS = T1PS * 2                      ;   double the postscaler
TimerConst = TimerConst / 2          ;   halve the count
  endw
TimerConst = 65536 - TimerConst      ; final reload value

[jamie_s]

Hi Darryl,

Currently getting an error with Latest MPLAB IDE:
MPLAB 8.90.00.00

PIC is an 18F45K22 and DT_INTS-18 is latest from your website, both MPLAM and DT_INTS were downloaded from the respective sites on 15/3/2013


ERROR: Unable to execute mpasmwin.Warning[206] M:\<FOLDERPATH><FILE>ASM 2170 : Found call to macro in column 1. (INT_ENABLE)
Error[116] M:\<FOLDERPATH><FILE>.ASM 696 : Address label duplicated or different in second pass (Z00032)
Error[116] M:\<FOLDERPATH><FILE>.ASM 759 : Address label duplicated or different in second pass (Z00033)
Error[116] M:\<FOLDERPATH><FILE>.ASM 812 : Address label duplicated or different in second pass (Z00034)
Error[116] M:\<FOLDERPATH><FILE>.ASM 843 : Address label duplicated or different in second pass (Z00035)

Can you advise if there is any fix for this or do i need to use an older version of MPLAB IDE

[mackrackit]

You might try here
http://support.melabs.com/threads/11...hlight=MPLAB-X

[Christopher4187]

I've used the DT_INTS sucessfully with an 18F4550. I had to move to an 18F87J50 but the DT_INTS would not compile. Not sure if I'm doing something wrong or if the DT_INTS was never tested with J series PIC's. When I compile, I get the following warning message:

Unable to fit variable VP_DelayCount in requested bank 0

In the "VirtualPort.bas" code, I changed this code:

VP_DelayCount  VAR WORD BANK0  ; Used for internal Delay only

to this:

VP_DelayCount  VAR WORD BANK1  ; Used for internal Delay only

and it compiled as expected. I have no clue if this will cause unexpected problems with my program or if this is the correct way to solve it but I haven't noticed any ill effects yet. Seems like this problem could be related to the SFR's but it's way above my level of knowledge.

Just thought I'd pass it along.