still in need bipolar stepper helpz!!! help.?
I have slept on the matter and still am in need this morning!
As far as the driver IC is concerned, again I think I would be good if someone who is better able to interpret the datasheets's block functional diagram could shed some insight into the particulars of the pins which are giving me trouble?? Specifically I am confused about: what to tie the phase pin(s) to (I assume it owuld be the uC or controlling circuit but am fuzzy about what I should issue- hi for what/low for what? The emmiter pin(s) I would imagine are tied to ground, no? (because the VM would be tied to the motors voltage source?) What about the timing pin(s), do these get their signals from the controlling device/circuit? or is there supposed to be a dedicated source for these signals designed? Does the current pin(s) get tied directly to vcc or are there circuits which are intended to alter the signal prior to driver? Finally the voltage ref pin(s) are supposed to be tied to one of the voltage sources- but which one? motor volts or logic volts?
Again the datasheet is very limited in coverage- it provides only the block diagram and maximum ratings breakdown- both of which are very helpfull but obviously not enough for my skill-level...........
any help with interpreting the device would be 1st on my wish list for today...secondly if a discrete solution might be a better fit and anyone can point me to a good design source which addresses short-combo protection using transistors rather than logic IC's that would be great also!
The key to the drive- either method -is to keep board size super little and lite! If I could make use of SMT transistors with a crafty layout which would amount to less area than dedicated IC's then I would rather go that route!
The current drivers I am using are only for testing the steppers- due to their inherit size restrictions (2 per motor) I wouldn't use them in final design ever. One other set of IC's I have handy are UN2803 darlington transistor arrays. from what I understand of them they are better suited for unipolar steppers- but in looking at their makup I wonder if they coult just as well be used for a bipolar stepper, even two per IC? Each device has 8 darlington pairs, stepper has four per- from what I understand the issue would be in controlling the transistors 'firing' ??Is this wrong? I cannot find any ref designs implementing bipolar steppers using the devices but it seems doable?
Bottom line I badly need some sort of tips to get a working design going for testing stage!! Still dunno if these steppers are going to be suitable for project!!