Use 4 steppers with 74HC595

[slmfd]

Hi, not an issue but a question. I want to free up pins of esp32s3, now i'am running 4 steppers with rmt driver. Can i run 4 steppers using 74HC595 with i2s?
It's a 4 automotive gauge steppers via sti6606z driver (only step+dir), so i don't have EN pins.

stepperMux0 = fastAccelStepperEngine.stepperConnectToPin(0 | PIN_I2S_FLAG, DRIVER_I2S_MUX);
stepperMux0->setDirectionPin(1 | PIN_I2S_FLAG);
stepperMux1 = fastAccelStepperEngine.stepperConnectToPin(2 | PIN_I2S_FLAG, DRIVER_I2S_MUX);
stepperMux1->setDirectionPin(3 | PIN_I2S_FLAG);
stepperMux2 = fastAccelStepperEngine.stepperConnectToPin(4 | PIN_I2S_FLAG, DRIVER_I2S_MUX);
stepperMux2->setDirectionPin(5 | PIN_I2S_FLAG);
stepperMux3 = fastAccelStepperEngine.stepperConnectToPin(6 | PIN_I2S_FLAG, DRIVER_I2S_MUX);
stepperMux3->setDirectionPin(7 | PIN_I2S_FLAG);

Will this work?
Thanks for this great library!

[gin66]

As per readme still need to configure the i2s mux:

// Initialize I2S Mux with data, bclk, and word select pins
// Not needed, if I2S direct mode is used
engine.initI2sMux(data_pin, bclk_pin, ws_pin);

// Connect stepper to I2S mux slot (0-31)
// PIN_I2S_FLAG automatically selects I2S Mux mode
stepper = engine.stepperConnectToPin(slot | PIN_I2S_FLAG);

// Direction and enable can also use I2S mux slots
stepper->setDirectionPin(dir_slot | PIN_I2S_FLAG, dirHighCountsUp);
stepper->setEnablePin(enable_slot | PIN_I2S_FLAG, activeLow);

Currently the I2S is configured to 16bit stereo. Not sure, what the 595 will make out of it.

There is extras/Esp32StepperDemo for experiments. Having some measurement equipment like oscilloscope or logic analyzer would be of help, if something is not working as expected. Using Esp32StepperDemo allows you to set/clear individual bits, so even multimeter can be sufficient.

For sure it is possible to change initialization to other I2S parameters, just not implemented yet.

Please let me know your results.

[slmfd]

Okay, i'll try. Thank you!

[slmfd]

Hi! I tried using 4 stepper drivers with the 74HC595. Three of them worked (channels 3-7), but one didn’t (channels 0-1). However, even the ones that worked were too slow for my project, so I went back to a direct connection using the RMT driver. Thanks!

[gin66]

There is a configuration option for mclk position, could be that channels 0-1 get mapped to 30-31

[slmfd]

Maybe somewhen i'll try again. But is very slow, and motor are moving not syncronous

[gin66]

hmm. 40ksteps/s should be achievable and there should not be any synchronicity issues.
Any chance to do some measurements with a logic analyzer or share a short video ?

[slmfd]

My settings for the RMT driver are 15,000 acceleration and a speed of 5,000 Hz (via setSpeedHz), and when switching to the 74HC595 I didn’t change these settings. The slowdown compared to RMT is about 2–3 times (approx). Sorry, but I’ll probably not reassemble the setup again, but if anything comes up I’ll definitely write here.

[gin66]

definitely unexpected result.I have ordered some 74HC595 devices to check, what‘s going on.