16F1827 interrupt hosed

[Darrel Taylor]

CALL or GOSUB doesn't make any difference.
But you cannot run Basic Language statements in an Assembly Language interrupt.
Re-use of PBP's system variables will corrupt the main programs flow.

If you want to use Basic statements in ASM interrupts, you need to either use ON INTERRUPT or DT_INTS.

[Macgman2000]

Darrel,

How would I structure my code using your interrupt include file? I want to accomplish the following:

1). update 4 servo's with a refresh rate of 16ms. Pulse width on the servos range between 1 ~ 2 ms based on reading 5 ADC channels.

Best Regards,
Nick

[Dick Ivers]

I found this in the new PBP3 Reference Manual on page 264

"Whenever a block of inline Assembly Language is entered, PBP sets the bank-select register to BANK0".

So, why does Nick have to manually select BANK0 using BANKSEL T1CON? It's true that all of the registers in his ISR are in BANK0. And yes, all his A to D registers are in BANK1, but why isn't PBP doing the switch to BANK0?

[cncmachineguy]

Good catch! Looks like I updated pbp but not my brain. Yet another good reason to upgrade

Darrel are you referring to the pauseus? If so are the rest non system variable things?

[Darrel Taylor]

Darrel are you referring to the pauseus? If so are the rest non system variable things?

if adcval < 4 and adcval2 < 4 and adcval3 <4 and adcval4 < 4 and adcval5 < 4 then

That is a compound if statement, meaning there is more than one condition to be tested.
That requires it to store intermediate results in T? temp variables, which are part of PBP's system vaiables.
The compares themselves will call a library function that uses R? system vars.

PAUSEUS will overwrite the R0 system variable.
PAUSE would use R0 and R1.

It's very difficult to know which statements will interfere with which system variables.
So it's best not to tempt fate.

[cncmachineguy]

Thanks Darrel

[Darrel Taylor]

... How would I structure my code using your interrupt include file? ...

I guess the structure would look a lot like the examples found here ... http://www.darreltaylor.com/DT_INTS-14/hello.html
Look at the Hello World, Blinky Light, Elapsed Timer and then how they are combined 1-3.