Output settings for 16F88

[skimask]

Actually that was even worse, the motor shaft just shatters back and forth makes no full turns

I expected all of the above...

Does this mean lots of harmonics and “dirt”, I do not have access to a scope where I am right now or I would have performed a ECG on it!

Basically, yes, FREQOUT is a bit ugly.

I think the problem in your code is here (and other places that look a lot like it):

DI = 1 : pause 500
for a = 0 to 200 : ST = 1 : pause 2 : ST = 0 : next a

Reading thru the code out loud:
- Step On
- Wait 2ms
- Step Off
- NO WAITing for 2ms
Repeat...

So basically what you end up with is a nice long 'go ahead and step' pulse, with practically no wait between pulses.

That might help you out. I don't know. I'm guessing here. Couldn't find the datasheet for that '5804 chip and didn't feel like doing any hard searching for it either

[PICante]

I’m back, after some fiddling I realized that without any delay it doesn’t work. Instead I removed the PAUSE and replaced it with a loop. Now, this part of the code looks like this:

for a = 0 to 2000 ‘ ten turns
ST = 1 ‘ start pulse
for b=0 to 59:next b
ST = 0 ‘ end pulse
next a ‘ loop

This runs the motor slightly faster, however if b < than 59 the motor loses all torque and just hums. At about b = 65 or higher the torque is acceptable and I really do not understand why it can't run faster.

UCN5804B: http://www.taomc.com/bits2bots/5804.pdf

Thanks!

[skimask]

This runs the motor slightly faster, however if b < than 59 the motor loses all torque and just hums. At about b = 65 or higher the torque is acceptable and I really do not understand why it can't run faster.

Because that's the nature of stepper motors.
Low speed / High torque
High speed / lower torque

And you still missed my point about the code above...
You've got a pause on one end of the step, but not the other end. The motor/electronics probably have to catch up with each other.

for a = 0 to 2000 ‘ ten turns
ST = 1 ‘ start pulse
for b=0 to 59:next b <-pause here ok
ST = 0 ‘ end pulse
might want a pause here, probably not the same length as above, but a pause nonetheless
next a ‘ loop

At 8Mhz, ST is low for maybe 4us, give or take.
And if you look at the datasheet, there's a turn-on and turn-off delay of 10us.

[PICante]

Thanks skimask!

Yes I did miss your point; of curse the "squarewave" must look better to the 5804 if the duty is more like 50/50!
New code:

for a = 0 to 2000 ‘ ten turns
ST = 1 ‘ start pulse
for b=0 to 28:next b ‘ on time
ST = 0 ‘ end pulse
for b=0 to 28:next b ‘ off time
next a ‘ loop

The motor runs at the same speed as before, perhaps with a little less noise. If I try to go below 28 it loses torque and I do not help to use different on and off times. I have tried both ways, shorter on time and shorter off time.
S**t, I really thought this was the solution!

[tenaja]

You *might* get a little more speed out of it if you ramp up to speed (i.e. set an acceleration rate) rather than instantly hitting the full speed.

But, as Skimask said, steppers are designed for low speed, and once you hit their top speed in the circuit, the motor will stall...which is a nice way to stay stop.