New board help requested

[pminmo]

I'm working on a new driver board based on a Atmel's AVR's (single chip micro) for the open source forum here. Long term intent is to have a low cost DIY three axis board, that will also have the pport connection and interface for limit switch and spindle. Attached is a grapic of a one axis board layout and schematic for software development. I doubt if I can get to doing an this actual board for several month's. If somebody would be willing to etch or mill one for a minimal fee, I could get to work on firmware.
Or if somebody want to do some code, or.........

The Attiny2313 is fast enough to handle a simple edge filter to make the input filter circuit on my other boards unnecessary. It is also inexpensive. It should be able to handle half step as well as full steps simply. The 3 axis board would have three of them.

Cost wise the 2313 is about $2.25 and the fets show are about $1.50 each. That adds up to a 3 axis board that could probably be built for under $45 worth of parts.

Phil

[vladdy]

If all you want a couple to evaluate the design with, I can pop off some quick TT style boards..
just give me a mailing address..

got some going in the etch tank tomorrow am.. can do easily,,all I need is Gerber, or Eagle / Pulsonix..

[pminmo]

Vladdy,
Look at your email. Thanks,
Phil

[tekno]

cound you tell me what the fed numbers are.

[pminmo]

Irlz44

[H500]

I'm playing with a similar designed based on a at90s2313 and a irl530. The result was very unsatisfactory. To get speed, it is necessary to use a high (35-45v) power supply and a chopper to control the current. A chopper can be implemented by adding a lm324 op amp to use as a pair of comparators to detect the coil current. With the o/p going to interrupts, the mcu can turn off the drive for a fixed time whenver the setpoint is exceeded.

I will try it this week as soon as I have time to write the program.

[jazz]

One of the issues here may be the drive capability of the micros. The irlz44 etc
have fairly large gate charge requirements (66nC). You may need to use some sort
of buffer circuit to drive the fet gates to get them to switch fast.

jazz

[ViperTX]

Originally Posted by pminmo Irlz44

If the FETs aren't the logic gate types...then that processor most likely won't be able to turn on the FET. Also I didn't check if you could do bit operations on the Micro's ports.

[pminmo]

H500,
To get the best speed out of a stepper, you have to run a higher PS voltage and current limit.
Jazz,
That is a concern, one of the reasons I wanted to protype.
Viper,
The AVR is bit programmable, and yes the FET is logic compatable.

Phil

[vladdy]

Got the PCB's out by snail the other day, bit of a delay, toner cart ran low in the HP, and topped up with generic toner, not as clean as before, so photo etched...
last photo is TT, piss poor..but good enough for a 'trial' anyways

you should have them in a few days..

enjoy..

[tekno]

Originally Posted by vladdy Got the PCB's out by snail the other day, bit of a delay, toner cart ran low in the HP, and topped up with generic toner, not as clean as before, so photo etched... last photo is TT, piss poor..but good enough for a 'trial' anyways you should have them in a few days.. enjoy..

did you etch you boards or have them done?

[pminmo]

vladdy,
Thanks.

Phil