Controlling 28 of the 28byj-48 (stepper motor 4pin dc)

[benepas]

Hi,

I want to controll a lot of stepper motors and was wondering about the best approach.

Could I use the MCP23017?
Or should I use these ATmega48A?
The goal is something like this https://www.youtube.com/watch?v=VU4PSbIvm04
In the video he's using some 74ch595 do I have to use those or could I use more Atmegas?

Thanks,

[groundFungus]

That is a very cool clock display.

I think that you will find that the consensus will be to use the shift registers or port expanders instead of multiple processors.

[benepas]

Ok thanks!

Could you recommend a good guide for using multiple port expanders?

[PaulRB]

I would recommend buying the motors without the ULN2003 driver boards. This should save some cash. Then use 14x TPIC6B595 shift registers to drive them. These can be chained together so that only 3 arduino pins are needed.

[benepas]

Could you explain further? @PaulRB How many driver would I need?

[PaulRB]

Tpic6b595 has 8 outputs so each chip can drive 2 stepper motors. 28 / 2 = 14

[benepas]

I would like to build each segment to be somewhat independent.

For one segment, could I use a wemos and 3 pins, sharing the clock and "flush" between 7 74hc595 shift registers that are connected in 1, 2, 4 pyramid where the 4 last ones go to the 7 steppers and the other just extends the first one and the first one is connected to the wemos.

Then I could just use 1 driver for each segment?

Does this sound viable?

Thanks!

[PaulRB]

Segment?

[benepas]

Sorry maybe bad wording, but one 7 segment display, so I would like to have 4 somewhat independent 7 segment display units

[benepas]

Kind of like this, using 1 microcontroller, into a 74hc595, into driver into a 74hc165 into many 74hc595 then finally into the motors?