Help with HPWM on 18f6520

[Andy Wood]

Thanks for the reply Skimask.

Here is a copy of the code:

main:

HPWM 1,127,245

HPWM 2,127,245

HPWM 3,127,245

HPWM 4,127,245

HPWM 5,127,245

GOTO main

When using a 5v supply, this produces 2.5v on CCP channels 1 and 2, and 0v on CCP channels 3,4 and 5 (which are on port G).

I also tried adding TRISG = 0 at the start, to force CCP 3,4 & 5 to outputs but nothing changed.

Andy

[skimask]

Thanks for the reply Skimask.
Here is a copy of the code:
main:
HPWM 1,127,245:HPWM 2,127,245:HPWM 3,127,245:HPWM 4,127,245:HPWM 5,127,245:GOTO main
When using a 5v supply, this produces 2.5v on CCP channels 1 and 2, and 0v on CCP channels 3,4 and 5 (which are on port G).
I also tried adding TRISG = 0 at the start, to force CCP 3,4 & 5 to outputs but nothing changed.
Andy

That's it? No defines, don't know how fast the oscillator is runng, no registers set up, no nothing?
Read the manual, try again...

[Bruce]

HPWM only works with CCP1 & CCP2. Beyond that, you'll need to manually configure hardware PWM.

[Andy Wood]

Hello Bruce,

Thanks for the reply. I have read the manual and cannot find where it says HPWM is only for CCP1 and CCP2. Maybe this is an undocumented "feature"?

Anyway, I do appreciate your response - I have been pulling my hair out! Thank you for your input.

Andy

[skimask]

Hello Bruce, Thanks for the reply. I have read the manual and cannot find where it says HPWM is only for CCP1 and CCP2. Maybe this is an undocumented "feature"? Anyway, I do appreciate your response - I have been pulling my hair out! Thank you for your input.
Andy

I think this is one of those times where...it's not that you can't find where it says HPWM is only for CCP1 and CCP2, but...Where does it state in the manual that HPWM can be used on any available PWM module? And I guess the answer is...you don't...therefore, you can't. I never thought about it myself, but the facts are the facts.
If PBP will compile HPWM 1 and HPWM 2 but not HPWM 3 - 5, then there ya go...

[Andy Wood]

Hello Skimask,

The confusing part is it compiled without listing any errors! it is just one of those things sent to try us I guess.....

Anyway, I have learned some more and that is what it is all about. Thanks again for your input.

Andy

[skimask]

Hello Skimask,

The confusing part is it compiled without listing any errors! it is just one of those things sent to try us I guess.....

Anyway, I have learned some more and that is what it is all about. Thanks again for your input.

Andy

I just looked at the pbppic18.lib file in the PBP directory and found this:

;************************************************* ***************
;* Default Hpwm values *
;************************************************* ***************

ifndef CCP1_REG ; CCP1 pin port
CCP1_REG EQU PORTC
endif
ifndef CCP1_BIT ; CCP1 pin bit
CCP1_BIT EQU 2
endif
ifdef CCP2CON
ifndef CCP2_REG ; CCP2 pin port
CCP2_REG EQU PORTC
endif
ifndef CCP2_BIT ; CCP2 pin bit
CCP2_BIT EQU 1
endif
endif

I don't know if the compiler will accept it, but I'm wondering if adding:

ifndef CCP3_REG ; CCP3 pin port
CCP3_REG EQU PORTG
endif
ifndef CCP1_BIT ; CCP3 pin bit
CCP3_BIT EQU 0
endif.......................................

and so on for channel 4 and 5 to that file...would enable the PWM modules for those channels.

This is above me without a usable 6520 (or anything else in that family) to play with at the moment.

DT, Mr_E? Any thoughts?

Also, you might want to check the chip's revision. The early 6520/6620/6720/8520/8620/8720 chips didn't like to run above 4mhz under certain conditions relating to code (I had a few of those, run all day at 4mhz, didn't like to run at 6mhz). Might want to check the errata sheets and see if you've got one. Of course, if you've bought it recently, or the date code is less than a year or two old, I wouldn't worry about it.