Let's Make Robots!

Timers and ... stuff

Hi all!

Been pretty busy lately digging in the big black timer.pngmystery box called Timer  on those nifty AVR controllers.

I think I finally have a clue how they work, and more then that, how they can be put to good uses. 

One application I'm going to do now that I have a clue, is to (try to) do microstepping. Yeah I blabbered about that other times too.

After a lot of testing and research (read that as googling around), I came to the conclusion that with the current stepper driver design, I'm just not being able to achieve that.

This  is due to several reasons:

1. I'm only able to PWM the enable pins of the L298 using the hardware PWM and while this works well for DC motors and other loads it does not  seem to go so well with steppers. I've seen designs doing just that (LadyAda's motor shield for example) but it looks like I just can't understand how, and I also wonder how well that works. I found lots of designs using some other chip to do current control in the windings but I don't want to do that. So the next design will have to be able to PWM the four inputs instead of the enable pins.

2. I designed that board with 12V in mind, I need more power, so I will go for 30V now, this should allow the Valkyrie to go smoother and faster 

3. That thing was done as my third self designed  PCB ever, I think I can do a nicer job now, I might also go for a double sided design ;) 

 

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I haven't got around digging in the black mystery box for timers yet, but those AVR's have several big black mystery box's if you ask me. I'm looking forward to see the results on this and the new PCB as well. I'd like to do a double-sided pcb one day as well, but I see the problems with it already. So good luck!

 -s

I will redesign later, until then I will test with an Attiny devel board + l293 board I made for a little bot ... Sadly the litle guy never got to power on :D

I will post when I get the time to do some teting, probably the upcomming  weekend.