I've decided that I want to get all the parts for this pan and tilt this week as I need to order some special connectors to fix a Mac Mini. So that means finally finishing my schematics!
Lets just say that working with EAGLE is more interesting than I had planned. This design is by far the most complicated one I have ever done before, I'm sure that is affecting my results a bit as well.
I've got a lot of clean up to do on the left side of the schematic, but here is what I have so far.
The whole thing is run with a standard ATMega328 chip - I could have gone with a larger chip with more memory but I think that the 328 will run well for now. Plus I have the same chip on an arduino board so it is a bit easier to prototype. I'm planning on being able to run 4 separate stepper motors simultaneously with the design; pan, tilt, slide, and an aux motor (focus?). It gives me a lot of room for expansion down the line. I've definitely got pan and tilt now but I plan to make a slide dolly in the future.
I'm running Stepstick motor controllers, so a lot of the circuitry is already taken care of. Most of the trivial settings for the stepsticks are connected via shift register on the ATMega to save pins (functions like microstepping and sleep). Those are then connected to header connectors on the board. I've kept away from directly wiring the outputs of the stepsticks to the stepper connectors because there are many different stepper motor pinouts and I can connect them in a higher speed or a higher torque setting as needed.
The board, however, is a mess. I'm running the freeware version of EAGLE so no 4 layer boards for me. :( This makes layout quite interesting as I've got to figure out where all of these gigantic through-holes are going to be as well as the smaller SMDs. Not to mention I still have to wire up the LCD display, a joystick controller, and a control button array.
So just a brief update now. I'm sure my writing skills are awful when I post at midnight, but that's what you get today :)
Hopefully more will come soon!