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These are stepper drivers! They run:
- ATSAMD51 Microcontrollers
- 2x A4950 H-Bridges on 2x DACs to VREF
- 1x AS5147 if you want to get closed-loop-fancy
- RS485 input and 40W 24V into one 10-pin IDC
To build one w/ a motor, for closed loop stepping, I do:
- N17 Motor 17HS19-2004S1
- IDC, Plug, 2x15 609-5106-ND
- IDC, Plug, 2x5 609-1746-ND
- Magnet 469-1076-ND
- Spacer 6mm Tall 94669A101
- M3 SHCS 50mm 91292A026
- DIP Switch 219-8LPSTRF
- 2x5 Latching 732-2679-ND
- Two Part Epoxy
The hardware is set up to run on the 'UCBus', a synchronous embedded protocol that establishes a bus clock *and* data lines on one RS485/UART Phy. Details are not documented anywhere ATM, but it w o r k s.
## Closed Loop
Circuits have a land for an AS5147P encoder, with which they can run closed-loop stepper control:
## Melted Version V02
I revisioned this recently to skip the module and just build the whole circuit on one board. Schematic is identical to V01, but now is much smaller (can fit on a NEMA14 size motor) and all components are SMT on one side, i.e. the AS5047P is on the same side as the H-Bridges, Micro etc.
The IDC UCBus connector & DIP Switch are on the flipped surface.
140 of these are out fab / assembly.
## Module Version V01
Beneath [the module](https://gitlab.cba.mit.edu/jakeread/ucbus-module).
Networked step driver (or) general purpose 2-H-Bridge ute. Uses module for micro / network drivers, all other parts are 0805 or similar to hand-solder easily.
## Voltages / VREFs etc
The A4950 VREFs are hooked up to DAC0 and DAC1.
Current limiting will be set by:
`Imax = Vref / (10 * Rs) ``
Where Rs is the sense resistor value, in this circuit its 0.2 ohms. So maximum current is 1.65A at 3.3v full DAC, all else scales. I think I set it up this way in case I was unable to set the DACs up properly, and had to turn them on full all the time.