Stepper Motor Control with Raspberry Pico PIO and DRV8711 driver- Part 7: autonomous PIO with interrupt when done

RE: Stepper Motor Control with Raspberry Pico PIO and DRV8711 driver- Part 7: autonomous PIO with interrupt when done

Jan Cumps — Wed, 16 Apr 2025 17:35:18 GMT

Frequency of stepper motor pulses is 100s of Hz max, maybe a few kHz for a specialised motor in micro-steps. I use a clock divider and a programmable delay to get the pulses to a manageable range.

But if you wonder: what's the maximum pulse speed of this design on a Pico 1 ([mention:0d133614bf01463a9e17ef49e25b2c0b:e9ed411860ed4f2ba0265705b8793d05] , not overclocked!)?

20MHz - definitely fast enough for anything stepper related for the next decades.

RE: Stepper Motor Control with Raspberry Pico PIO and DRV8711 driver- Part 7: autonomous PIO with interrupt when done

DAB — Tue, 15 Apr 2025 19:30:58 GMT

Nice post Jan.

RE: Stepper Motor Control with Raspberry Pico PIO and DRV8711 driver- Part 7: autonomous PIO with interrupt when done

Jan Cumps — Tue, 15 Apr 2025 17:43:30 GMT

object oriented version: [mention:301aa380c4e84007a488aadeebc7fbd4:f7d226abd59f475c9d224a79e3f0ec07:label=Handle%20Raspberry%20Pico%20PIO%20%26quot%3Brelative%20interrupts%26quot%3B%20in%20C%2B%2B]

RE: Stepper Motor Control with Raspberry Pico PIO and DRV8711 driver- Part 7: autonomous PIO with interrupt when done

Jan Cumps — Sun, 13 Apr 2025 10:14:07 GMT

The explanation of relative IRQ is a bit fuzzy. I've created a table with what the PIO actually throws (int) when choosing state machine (sm) 0 - 3 and IRQ 0 - 3

SDK:

RE: Stepper Motor Control with Raspberry Pico PIO and DRV8711 driver- Part 7: autonomous PIO with interrupt when done

DAB — Sat, 12 Apr 2025 19:22:00 GMT

Nice update Jan.

RE: Stepper Motor Control with Raspberry Pico PIO and DRV8711 driver- Part 7: autonomous PIO with interrupt when done

ahsrabrifat — Sat, 12 Apr 2025 18:38:11 GMT

Have you written any content on the introduction to PIO?

RE: Stepper Motor Control with Raspberry Pico PIO and DRV8711 driver- Part 7: autonomous PIO with interrupt when done

Jan Cumps — Sat, 12 Apr 2025 18:31:03 GMT

> watchout 1: each PIO can run 4 motors. I haven't added the logic yet to know which motor is finished. That's for a next blog.

I have this solved. You can add the state machine index to the interrupt # in PIO, by adding the rel clause

[embed:dc8ab71f-3b98-42d9-b0f6-e21e02a0f8e2:414ba5c4-d3a5-4fa1-9a88-81905275b0ba:type=text&text=%20%20%20%20irq%20PIO_IRQ_DONE%20rel%20%20%20%20%20%20%20%20side%200%20%3B%20flag%20that%20the%20job%27s%20done]

In this case, state machine 0 will throw interrupt 0, SM 1 interrupt 1, ...

In C, I had to change a few things to take that into account. First the handler:

[embed:dc8ab71f-3b98-42d9-b0f6-e21e02a0f8e2:eaf348b2-f87f-470e-afa3-625e41d9ab32:type=c_cpp&text=void%20pio_irq_handler%28void%29%7B%0D%0A%20%20%20%20if%28pio_interrupt_get%28piostep%2C%20stepper_PIO_IRQ_DONE%20%2B%20sm%29%29%20%20%20%20%20%7B%0D%0A%20%20%20%20%20%20%20%20pio_interrupt_clear%28piostep%2C%20stepper_PIO_IRQ_DONE%20%2B%20sm%29%3B%0D%0A%20%20%20%20%20%20%20%20commands_completed%20%3D%20commands_completed%20%2B%201%3B%0D%0A%20%20%20%20%7D%0D%0A%7D]

(note: my code only entertains 1 motor. I'd make an array of commands_completed if I had more motors.)

And the interrupt register needs to be refined too:

[embed:dc8ab71f-3b98-42d9-b0f6-e21e02a0f8e2:ebd8534a-b43e-485f-933f-bbe047d71030:type=c_cpp&text=%20%20%20%20pio_set_irq0_source_enabled%28piostep%2C%20static_cast%3Cpio_interrupt_source%3E%28std%3A%3Ato_underlying%28pis_interrupt0%29%20%2B%20sm%29%20%2C%20true%29%3B%20]

That's it. I'll make a demo that runs 2 motors on the same state machine to showcase this.