Motor Control Pulse Width Modulator (MCPWM) #93

usbalbin · 2022-06-26T21:01:41Z

Example:

let peripherals = Peripherals::take().unwrap();
let config = OperatorConfig::default().frequency(25.kHz().into());
let mcpwm = Mcpwm::new(peripherals.mcpwm0.mcpwm)?;
let mut operator = Operator::new(
    peripherals.mcpwm0.operator0,
    &mcpwm,
    &config,
    peripherals.pins.gpio4,
    peripherals.pins.gpio5,
)?;

operator.set_duty_a(my_duty_percentage_a)?; // Set duty for pin 4
operator.set_duty_b(my_duty_percentage_b)?; // Set duty for pin 5

Todo:

usbalbin · 2022-06-26T21:05:03Z

~~Have not have had time to check if this even compiles since my last changes...~~

Anyways is this somewhat what we want things to look like api wise? :)

usbalbin · 2022-06-30T20:32:19Z

~~Is this perhaps to be considered blocked on some sort of ESP/ESP-S3 CI?~~ - #96 merged

MabezDev · 2022-07-05T10:33:19Z

Sorry! I went on vacation, and I was also waiting on some hardware so I can test this out :). Taking a look into this now.

usbalbin · 2022-07-05T19:14:10Z

No worries :)

MabezDev

Sorry for taking so long to review this! Appreciate your patience :). It's looking good! I don't have any strong opinions on the API, what you have come up with seems pretty good to me!

I think some TODO's need to be addressed, I've commented on most of them where I think they should be. The rest could be left as TODO, as I understand its quite an amount of effort implementing the whole MCPWM API

src/mcpwm.rs

MabezDev · 2022-07-14T12:16:58Z

src/mcpwm.rs

+ // * High res => small prescaler => better maintan accuracy at high frequency, unable to reach lower freq
+ // * Lower res => larger prescaler => worse accuracy at high frequency(still as good at low frequency),
+ // able to reach lower freq
+ // Would it make more sense to expose it as "lowest reachable frequency"


Would it make more sense to expose it as "lowest reachable frequency"

I think this is the best way to express it, makes more sense this way imo.

What happens if prescaler register value does not fit into the least significant 8 bits?

Probably bad things :D. We can either add the check here or PR to esp-idf and fix it there.

src/mcpwm.rs

examples/mcpwm-simple.rs

src/mcpwm.rs

usbalbin · 2022-07-21T00:02:55Z

src/mcpwm.rs

+ return Err(EspError::from(ESP_ERR_INVALID_ARG).unwrap());
+ }
+
+ let resolution = u32::from(config.lowest_frequency) * MAX_PWM_TIMER_PERIOD;


This is related to what I mentioned earlier

Should we clamp resolution to not be greater than mcpwm_module.operator_source_frequency?

src/mcpwm.rs

usbalbin · 2022-07-24T11:21:03Z

src/mcpwm.rs

+ // TODO: Is this actually true? --------
+ // |
+ // v
+ /// MCPWM_ACTIVE_HIGH_COMPLIMENT_MODE - The most common deadtime mode


The most common deadtime mode
This mode seemed like the one making most sense to me... Is this true or should I remove that comment? :)

It might be true (idk :D) but I'd say remove the comment regardless.

src/mcpwm.rs

MabezDev · 2022-07-24T17:30:55Z

src/mcpwm.rs

+ // TODO: Is this actually true? --------
+ // |
+ // v
+ /// MCPWM_ACTIVE_HIGH_COMPLIMENT_MODE - The most common deadtime mode


It might be true (idk :D) but I'd say remove the comment regardless.

src/mcpwm.rs

usbalbin · 2022-08-06T15:54:07Z

This also works fine:

#[cfg(any(esp32, esp32s3))]
fn main() -> anyhow::Result<()> {
    use embedded_hal::delay::blocking::DelayUs;
    use esp_idf_hal::delay::FreeRtos;

    esp_idf_sys::link_patches();

    let v = f32::from(159_u16) * 0.1;
    println!("159 to float is={v}");

    let v = f32::from(160_u16) * 0.1;
    println!("160 to float is=some number");
    
    let v = v + 0.1;
    println!("is={v}");
    

    loop {
        FreeRtos.delay_ms(10)?;
    }
}

usbalbin · 2022-08-06T16:04:30Z

#[cfg(any(esp32, esp32s3))]
fn main() -> anyhow::Result<()> {
    esp_idf_sys::link_patches();

    let v = 16.0;
    println!("f32 literal is={v}");

    let v = f32::from(16_u16);
    println!("Converting the number seems to work");
    println!("from u16 to f32 is={v}"); // Boom
    loop {}
}

usbalbin · 2022-08-06T18:39:17Z

Created #112 since I think the problem might be unrelated to this PR

usbalbin · 2022-08-06T23:33:08Z

Reading the IDF 4.4 to 5.0 migration guide

The legacy driver has an inappropriate assumption, that is the MCPWM operator should be connected to different MCPWM timer. In fact, the hardware doesn’t have such limitation. In the new driver, a MCPWM timer can be connected to multiple operators, so that the operators can achieve the best synchronization performance.

This changes a lot of things. Something we should think of now right away or save for a later PR?

MabezDev · 2022-08-18T14:11:23Z

Sorry, I haven't forgotten about this! I will try to review this early next week.

usbalbin · 2022-09-02T09:59:03Z

Hi @MabezDev ,

No rush, just a friendly reminder :)

liebman · 2022-09-23T22:53:59Z

These four methods are needed for Operator when dealing with brushed motors:

    /// set 'a' low
    pub fn set_low_a(&mut self) -> Result<(), EspError> {
        unsafe {
            esp!(esp_idf_sys::mcpwm_set_signal_low(
                U::unit(),
                O::timer(),
                esp_idf_sys::mcpwm_generator_t_MCPWM_GEN_A
            ))
        }
    }

    /// set 'b' low
    pub fn set_low_b(&mut self) -> Result<(), EspError> {
        unsafe {
            esp!(esp_idf_sys::mcpwm_set_signal_low(
                U::unit(),
                O::timer(),
                esp_idf_sys::mcpwm_generator_t_MCPWM_GEN_B
            ))
        }
    }

    /// set 'a' high
    pub fn set_high_a(&mut self) -> Result<(), EspError> {
        unsafe {
            esp!(esp_idf_sys::mcpwm_set_signal_high(
                U::unit(),
                O::timer(),
                esp_idf_sys::mcpwm_generator_t_MCPWM_GEN_A
            ))
        }
    }

    /// set 'b' high
    pub fn set_high_b(&mut self) -> Result<(), EspError> {
        unsafe {
            esp!(esp_idf_sys::mcpwm_set_signal_high(
                U::unit(),
                O::timer(),
                esp_idf_sys::mcpwm_generator_t_MCPWM_GEN_B
            ))
        }
    }

usbalbin · 2022-09-24T08:54:39Z

These four methods are needed for Operator when dealing with brushed motors:

Any suggestions for how to undo the effect of those methods? How do I restore the normal behaviour after, for example, set_low_a has been called? Also note that the answer might depend on whether MCPWM from IDF <= 4.4 or from IDF 5.0 is used. (IDF <= 4.4 for this PR, 5.0 for #132).

As far as I know, for IDF 4.4 I believe mcpwm_set_duty_type has to be called to restore output. Have not looked into any 5.0 equivalent yet. Please correct me if I am wrong

liebman · 2022-09-24T11:57:41Z

You are correct. mcpwm_set_duty_type is needed as well. (missed that when I pulled the others from my C++ brushless motor driver.)

liebman · 2022-09-24T20:43:59Z

Question: (and this probably reveals my naiveté with rust)
How can I represent one of the motor operators generically - like in a system where I'm controlling three motors say left wheel, right wheel, and lidar motor. I want to store a reference (or pass ownership) to another struct... but the signature make it difficult as I'll have more than one instance each using separate operators:

Operator<U: Unit, O: HwOperator<U>, M: Borrow<Mcpwm<U>>, PA: OutputPin, PB: OutputPin>

Thoughts? (even RTFM if you have a pointer)

usbalbin · 2022-09-26T08:00:35Z

Question: (and this probably reveals my naiveté with rust) How can I represent one of the motor operators generically - like in a system where I'm controlling three motors say left wheel, right wheel, and lidar motor. I want to store a reference (or pass ownership) to another struct... but the signature make it difficult as I'll have more than one instance each using separate operators:
Operator<U: Unit, O: HwOperator<U>, M: Borrow<Mcpwm<U>>, PA: OutputPin, PB: OutputPin>
Thoughts? (even RTFM if you have a pointer)

Great question! Hard to say without knowing more. However assuming you want to have two operators live in the same struct sharing the same mcpwm module(also living in the struct), then perhaps something like(not tested):

struct Foo<U: Unit, O0: HwOperator<U>, O1: HwOperator<U>, P0B: OutputPin, P0B: OutputPin> 
where
    U: Unit,
    O0: HwOperator<U>,
    O1: HwOperator<U>,
    P0A: OutputPin, P0B: OutputPin,
    P1A: OutputPin, P1B: OutputPin
{
    mcpwm: Arc<Mcpwm<U>>,
    operator0: Operator<U, O0, Arc<Mcpwm<U>>, P0A, P0B>,
    operator1: Operator<U, O1, Arc<Mcpwm<U>>, P1A, P1B>,
}

or something like this if you want to have the mcpwm module live outside the struct(not tested):

struct Bar<'a, U, O0, O1, P0B, P0B> 
where
    U: Unit,
    O0: HwOperator<U>,
    O1: HwOperator<U>,
    P0A: OutputPin, P0B: OutputPin,
    P1A: OutputPin, P1B: OutputPin
{
    operator0: Operator<U, O0, &'a Mcpwm<U>, P0A, P0B>,
    operator1: Operator<U, O1, &'a Mcpwm<U>, P1A, P1B>,
}

Let me know if this answered your question :)

liebman · 2022-09-26T19:31:47Z

Yes - that was very helpful! This worked:

pub struct MotorMCPWM<'d, U: Unit, O: HwOperator<U>, PA: OutputPin, PB: OutputPin>
{
    operator: Operator<U, O, &'d Mcpwm<U>, PA, PB>,
    direction: Direction,
    percent: Percent,
    invert: bool,
}

impl<'d, U: Unit, O: HwOperator<U>, PA: OutputPin, PB: OutputPin> MotorMCPWM<'d, U, O, PA, PB>
{
    pub fn new(mcpwm: &'d Mcpwm<U>, operator: O, pin_ph: PA, pin_en: PB, invert: bool) -> Result<Self, EspError>
    {
        info!("MotorMCPWM::new ph={} en={}", pin_ph.pin(), pin_en.pin());
        let config = OperatorConfig::default().frequency(50.Hz());
        Ok(Self {
            operator: Operator::new(
                operator,
                &*mcpwm,
                &config,
                pin_ph,
                pin_en,
            )?,
            direction: Direction::Stopped,
            percent: 0 as Percent,
            invert: invert,
        })
    }
}

And code not shown implements the following trait to make the motor generic, letting me not have everything having to deal with the long type specification.

pub type Percent = f32;

#[derive(Clone, Copy, Debug)]
pub enum Direction {
    Stopped,
    Forward,
    Reverse,
}

pub trait Motor {
    type Error;
    fn set_percent(&mut self, percent: Percent) -> Result<(), Self::Error>;
    fn set_direction(&mut self, direction: Direction) -> Result<(), Self::Error>;
}

MabezDev · 2022-11-13T20:22:07Z

Hi @usbalbin, firstly I want to apologize for the time between reviews. We've had a succession of compiler issues in the last couple of releases (one of which you found :D) and most of my time has been spent digging into that.

Looking at this again, and the surrounding discussion this looks good to me! My understanding is that #132 builds on top of this PR, so we should merge this first?

I think this is ready to merge as is, would you mind rebasing on the main branch?

usbalbin · 2022-11-14T16:14:23Z

Hi @usbalbin, firstly I want to apologize for the time between reviews. We've had a succession of compiler issues in the last couple of releases (one of which you found :D) and most of my time has been spent digging into that.

No worries :)

[...] My understanding is that #132 builds on top of this PR, so we should merge this first?

In the sense git sense, sure. However it has since been modified beyond recognition to better fit with how things are exposed in MCPWM from IDF 5, see comment for more info.

One of the bigger differences being that timer and operator are two independent things in #132. So #132 would very much be a breaking change. However at the same time this pr (#93) is for IDF < 5 while #132 is for IDF >= 5...

Going the other way, using some clever generic bounds there might be possible to make something that looks like #132 work for IDF < 5 but with lots of restrictions like timer1 can only connect to operator1...

I am happy either way, and I will attempt a rebase soon

Example usage of #92 (this PR)

let peripherals = Peripherals::take().unwrap();
let config = OperatorConfig::default().frequency(25.kHz().into());
let mcpwm = Mcpwm::new(peripherals.mcpwm0.mcpwm)?;
let mut operator = Operator::new(
    peripherals.mcpwm0.operator0,
    &mcpwm,
    &config,
    peripherals.pins.gpio4,
    peripherals.pins.gpio5,
)?;

operator.set_duty_a(my_duty_percentage_a)?; // Set duty for pin 4
operator.set_duty_b(my_duty_percentage_b)?; // Set duty for pin 5

Example usage of #132

(Not tested)

let operator_config = OperatorConfig::default();
let timer = Timer::new(peripherals.mcpwm0.timer0, timer_config);

let mut timer = timer.into_connection().attatch_operator0( // This is the connection between a timer and 0-3 operators
    peripherals.mcpwm0.operator0,
    operator_config,
    peripherals.pins.gpio4,
    peripherals.pins.gpio5,
);


// This hands out mutable references to the contained timers and operators
let (timer, operator, _unused_operator_slot1, _unused_operator_slot2) = timer.split();

let period_ticks = timer.get_period_peak();
operator.set_duty_a(my_duty_ticks_a)?; // Set duty for pin 4 in units of timer ticks
operator.set_duty_b(my_duty_ticks_b)?; // Set duty for pin 5

usbalbin · 2022-11-14T16:32:46Z

Do you want me to reduce the number of commits? If so, then how? One commit or multiple?

MabezDev · 2022-11-16T11:45:06Z

One of the bigger differences being that timer and operator are two independent things in #132. So #132 would very much be a breaking change. However at the same time this pr (#93) is for IDF < 5 while #132 is for IDF >= 5...

Going the other way, using some clever generic bounds there might be possible to make something that looks like #132 work for IDF < 5 but with lots of restrictions like timer1 can only connect to operator1...

Perhaps then we should actually develop the interface for esp-idf v5 first then, if it's more flexible? We can then re-use that same interface for v4.4 but with the caveat that we panic if operator0 is not used with the timer0 for example. Along the way, we might find we can enforce this with generic bounds, but If not I still think it's perfectly fine to panic in that situation.

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usbalbin mentioned this pull request Jun 28, 2022

Motor Control Pulse Width Modulator (MCPWM) #92

Open

usbalbin added 4 commits July 14, 2022 06:49

The beginning of a first rough draft...

b42c6d5

Fix some of the TODOs, disable example for esp variants without mcpwm

507dd8b

Fix clippy lints

e4ed558

Update cfg's

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usbalbin force-pushed the mcpwm branch from a2e7b9b to 1e2a947 Compare July 14, 2022 04:49

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usbalbin added 4 commits July 15, 2022 21:24

use esp_idf_sys::*

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Address some of the comments and add deadtime support

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Clippy

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Fix warnings in example

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Fix example

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Add some docs for deadtime modes

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Added Mcpwm::operator_source_frequency

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usbalbin mentioned this pull request Aug 6, 2022

Crash or strange result when printing f32 #112

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usbalbin added 6 commits August 8, 2022 19:11

Work around float printing issue

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Clarify deadtime

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Some cleanup

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Fix some methods missing their self

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07691e7

Explain example mcpwm-simple

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usbalbin marked this pull request as ready for review August 12, 2022 15:24

usbalbin added 3 commits August 31, 2022 14:02

Allow setting initial duty in OperatorConfig

018056a

Clamp timer resolution to not be greater than timer group resolution

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Expose Mcpwm's unit and Operator's timer

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usbalbin force-pushed the mcpwm branch from 6119389 to 52e4542 Compare September 2, 2022 08:55

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MCPWM 5.0 #132

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Merge branch 'master' into mcpwm

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Motor Control Pulse Width Modulator (MCPWM) #93

Motor Control Pulse Width Modulator (MCPWM) #93

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Motor Control Pulse Width Modulator (MCPWM) #93

Are you sure you want to change the base?

Motor Control Pulse Width Modulator (MCPWM) #93

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Example usage of #92 (this PR)

Example usage of #132

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