20X2 HPWM problem

afb

Member
Hi ya

I'm using a 20X2 which processes various RC input signals, reads a couple of pots and three jumper links, has several digital outputs and also gebnerates a single PWM stream.

Having designed and built a strip-board layout I wrote some trivial test programs to exercise the hardware before starting on the programming proper. The bits all worked in isolation.

All was going well until I found one of my (previously tested) jumper link inputs had frozen into the low condition (it's normally pulled up by a 47K resistor, and the jumper, if fitted, links it to 0v). After some effort I have determined that invoking the HPWM command is responsible for pulling it low.

To eliminate my software application I wrote the following program

high B.7 'turns the LED on - just so I know its working
pause 3000 'time to see input C.0 (leg 10) is sitting high

hpwm 0,0,%0100,100,50 'I'm using HPWM C (leg 7)

do 'prevent HPWM terminating
loop

sure enough after 3 seconds leg 10 takes a dive to 0v. The PWM on leg 7 runs just fine. I've even bent the entire HPWM set of legs out of the socket and C.0 is still pulled low.

Any ideas????
 

afb

Member
UPDATE

I've altered my layout so that I can use the regular PWM on C.5 instead - and everything works fine now, so I'm not stuck, but I'm still curious !
 
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