ESP32: New hardware PCNT Counter() and Encoder(). #6639

IhorNehrutsa · 2020-11-20T22:05:14Z

This PR consistent to
docs\machine: Add Counter and Encoder classes #8072

ESP32 Pulse Counter
https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/peripherals/pcnt.html

Wrapped around
https://github.com/espressif/esp-idf/blob/master/components/driver/include/driver/pcnt.h
https://github.com/espressif/esp-idf/blob/master/components/hal/include/hal/pcnt_types.h
https://github.com/espressif/esp-idf/blob/master/components/driver/pcnt.c

See also
https://github.com/espressif/esp-idf/tree/master/examples/peripherals/pcnt/pulse_count_event

ESP32 Quadrature Encoder based on Pulse Counter(PCNT)
Based on
https://github.com/madhephaestus/ESP32Encoder
https://github.com/bboser/MicroPython_ESP32_psRAM_LoBo/blob/quad_decoder/MicroPython_BUILD/components/micropython/esp32/machine_dec.c

See also
https://github.com/espressif/esp-idf/tree/master/examples/peripherals/pcnt/rotary_encoder

If your port does not support hardware encoder use machine.Pin() Interrupt-based MicroPython quadrature incremental encoder

UPDATE:
This pull request is not possible to rebase on master.
Please switch to the
ESP32: Add Quadrature Encoder and Pulse Counter classes. #8766

peterhinch · 2020-11-21T10:01:52Z

To offer a general comment, encoder interfaces are difficult because of the effects of vibration. Accuracy can be lost as the inputs can experience brief pulses of arbitrary duration. These don't constitute systematic rotation but can be wrongly interpreted as such.

I haven't studied the code in detail but the fact that this solution offers detection of rising, falling, or both edges rings an alarm bell: in my experience the state machine must detect both edges to avoid loss of precision in the presence of vibration.

Rename enum puType to pullResistor. Rename enum encType to clockMultiplier and it content. Rename class EncoderType to ClockMultiplier.

IhorNehrutsa · 2020-11-24T08:47:01Z

To all. Could someone test the pulse counter and quadrature counter in industrial hardware with a big PPR?

peterhinch · 2020-11-24T09:04:03Z

While that is worthwhile, it is hard to replicate the situation where the encoder is positioned precisely at a transition and machine vibration causes jitter around that point. That is best simulated with a pulse generator over a range of pulse widths. There is a risk of creating an interface where small positional errors only become apparent after days of continuous machine running.

robert-hh · 2021-09-21T20:08:04Z

How does the QUAD API code return the direction of the rotation in addition to the counts?

harbaum · 2022-01-23T11:17:11Z

ports/esp32/machine_encoder.c

+STATIC void register_isr_handler(void) {
+    if (pcnt_isr_handle == NULL) {
+        check_esp_err(pcnt_isr_register(pcnt_intr_handler, (void *)0, (int)0, (pcnt_isr_handle_t *)&pcnt_isr_handle));
+        if (pcnt_isr_handle == NULL) {
+            mp_raise_msg(&mp_type_Exception, MP_ERROR_TEXT("wrap interrupt failed"));
+        }
+    }
+}


Using pcnt_isr_handler_add() instead would give the unit demultiplexing inside the isr handler for free, in turn simplifying the whole handler. See .e.g https://github.com/espressif/esp-idf/blob/faf0f61cdba67fa5f7e680f2f5b0966c8d69ce9a/examples/peripherals/pcnt/pulse_count_event/main/pcnt_event_example_main.c

jonathanhogg · 2022-01-23T12:40:21Z

This implements two types of counters on top of the the esp32 PCNT. Why was this solution choosen over a direct implementation of the PCNT API? The Counter and Encoder could then easily be subclassed from machine.PCNT leaving all the options of the underlying hardware available for other type of counters.

The intent is to have a common MicroPython API that works across different ports that implement counting and quadrature decoding in different ways. There has been much discussion of this issue across this PR and #8072, #7911, #7582, #5216 and #5496.

Perhaps someone in the future will have a burning need to use some missing feature of the raw hardware and will refactor this implementation to work on top of a new esp32.PCNT class instead. As the author of a direct implementation of the PCNT API (#7582) that I am using in production equipment, I personally feel that there is little additional functionality in the underlying hardware that is worth the additional complexity.

Right now I feel like just getting anything into mainline would be great.

harbaum · 2022-01-23T14:46:48Z

Right now I feel like just getting anything into mainline would be great.

I don't really agree with the anything.

But anyway, I think that adding a simple esp32 specific module is more likely to work as this would not depend on any yet-to-agree-on API. But a python module subclassing from that could easily be added implementing these APIs once they become available.

additional complexity.

I don't think there's additional complexity, PCNT is rather simple. Both counter modules together are IMHO more complex than a simple wrapper module around PCNT. And the python subclasses don't count as there's no need to make them part of the firmware although you could of course freeze them into it if you wish to.

docs/esp32/pcnt.rst

IhorNehrutsa · 2022-01-24T09:15:07Z

@harbaum

This has changed in IDF 4.3 and there's now pcnt_get_event_status() for this.

The pcnt_get_event_status() may be use later when MicroPython will use IDFv4.3.

MicroPython v1.18 on 2022-01-17; ESP32 module with ESP32
Type "help()" for more information.
>>> import platform
>>> platform.platform()
'MicroPython-1.18.0-xtensa-IDFv4.2.2-with-newlib3.0.0'

docs/esp32/pcnt.rst

jonathanhogg · 2022-01-24T19:34:22Z

Honestly, I'm not sure why the esp32/pcnt.rst file exists. I don't ever see that file being pulled into mainline.

The documentation for the full common API should be covered by #8072, with any port differences summarised briefly in esp32/quickref.rst. This would be the approach used for all of the other machine documentation.

IhorNehrutsa · 2022-01-25T06:44:49Z

Honestly, I'm not sure why the esp32/pcnt.rst file exists. I don't ever see that file being pulled into mainline.

The pcnt.rst was added more then year ago.
I propose to leave this question to @dpgeorge consideration.

harbaum · 2022-02-01T20:41:44Z

ports/esp32/machine_encoder.c

+                if (PCNT.status_unit[id].ZERO_LAT) {
+                    if (self->counter == 0) {
+                        self->status |= EVT_ZERO;
+                        mp_sched_schedule(self->handler_zero, MP_OBJ_FROM_PTR(self));


How is this supposed to be used by the user? This triggers when the hardware counter passes zero but the event is only scheduled if self->counter also is zero.

But the user setting the counter using value() imho can set an arbitrary offsets on self->counter to values != 0. Then the hardware counter and self->counter won't pass zero at the same time. Or am I misunderstanding something?

harbaum · 2022-02-03T17:25:29Z

ports/esp32/machine_encoder.h

+    int aPinNumber;
+    int bPinNumber;
+
+    volatile int64_t counter;


I am trying to understand how self->counter is supposed to work. And I am not sure it actually does what it's intended to. This is my understanding:

self->counter serves two purposes: a) it's something like additional upper bits for the 16 bit hardware counter and b) it allows to set the counter to any value which the hardware counter does not allow. self->counter then basically becomes an offset

The problem I see is in the trigger events of the hardware counter, especially EVT_ZERO. The hardware triggers only on the hardware counter. The interrupt routines try to take this into account by additionally comparing self->counter with zero or the match values. This may actually work as long as self->counter is only used as the upper bits. But it will IMHO fail if it's used to adopt to the fact that the hardware counter cannot be set. If self->counter is set instead while the user tries to set the counter then the hardware counter and self->counter imho get out of sync. And thus they'll not pass the trigger values at the same time. Thus they e.g. don't pass zero at the same time and the EVT_ZERO will not trigger and it seems to me that the match triggers also won't work as intended.

AmirHmZz · 2022-05-24T04:41:15Z

Thanks for everyone who is working on this! Any updates on merging this PR? @dpgeorge

Just rebase to Version 1.19.xx from micropython#6639

IhorNehrutsa · 2022-06-16T21:47:42Z

This pull request is not possible to rebase on master.
Please switch to the
ESP32: Add Quadrature Encoder and Pulse Counter classes. #8766

readline: make ctrl-l clear screen & redraw line

Just rebase to Version 1.19.xx from micropython#6639

projectgus · 2024-03-07T23:53:05Z

This is an automated heads-up that we've just merged a Pull Request
that removes the STATIC macro from MicroPython's C API.

See #13763

A search suggests this PR might apply the STATIC macro to some C code. If it
does, then next time you rebase the PR (or merge from master) then you should
please replace all the STATIC keywords with static.

Although this is an automated message, feel free to @-reply to me directly if
you have any questions about this.

IhorNehrutsa added 7 commits November 20, 2020 16:00

esp32/esp32_pcnt.* : Add files for Pulse counter and Quadrature encoder.

c6d6dce

esp32/modesp32.*: Add PCNT() & QUAD() to esp32 momdule.

ca67883

Test

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add

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EspError, PCNT, QUAD test Ok

88ade12

Formatting

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Formatting

3a29d6a

IhorNehrutsa changed the title ~~Feature/esp32 pcnt quad~~ ESP32: New features PCNT() and QUAD() Nov 20, 2020

IhorNehrutsa added 5 commits November 22, 2020 23:10

ESP32 PCNT QUAD: Add documentation and hide some methods and consts.

3f47cfc

Rename enum puType to pullResistor. Rename enum encType to clockMultiplier and it content. Rename class EncoderType to ClockMultiplier.

ESP32 PCNT QUAD: Fix documentation and delete duplicates in code.

a7386a3

ESP32 PCNT QUAD: Formatting

3deaa23

ESP32 PCNT QUAD: Formatting

fb1a533

esp32/esp32_pcnt.c: Use ESP_EXCEPTIONS() macro.

d12c849

IhorNehrutsa mentioned this pull request Nov 27, 2020

esp32/machine_pwm.c: Handle multiple timers: Bugfix PWM.deinit() critical error and fix pwm_print() #6654

Closed

IhorNehrutsa mentioned this pull request Dec 5, 2020

esp32/machine_pwm: handle multiple timers. #6276

Closed

IhorNehrutsa mentioned this pull request Dec 15, 2020

Roadmap for next release (v1.11 -> v2.0?) #4821

Open

17 tasks

Merge branch 'master' into feature/esp32_pcnt_quad

c9501e8

IhorNehrutsa mentioned this pull request Jul 26, 2021

esp32/esp32_pcnt: Add PCNT class and Counter/Encoder shims in machine #7582

Open

dpgeorge added the port-esp32 label Jul 26, 2021

IhorNehrutsa added 3 commits September 21, 2021 22:52

revert gitignore

d7bd201

Remove esp_error.c and esp_error.h

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Revert EspError

1c5cabf

IhorNehrutsa changed the title ~~ESP32: New features PCNT() and QUAD()~~ ESP32: New features PCNT() and QUAD(). Sep 21, 2021

IhorNehrutsa added 3 commits September 22, 2021 00:25

Remove EspError

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Update esp32.rst

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Update CMakeLists.txt

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harbaum reviewed Jan 23, 2022

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harbaum mentioned this pull request Feb 1, 2022

Frozen python code as part of machine module? #8241

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Proposal: Esp32 machine.PCNT through Encoder.py and Counter.py #8253

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IhorNehrutsa added a commit to IhorNehrutsa/micropython that referenced this pull request Jun 16, 2022

ESP32 PCNT: Add Counter and Encoder.

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Just rebase to Version 1.19.xx from micropython#6639

IhorNehrutsa mentioned this pull request Jun 16, 2022

ESP32: Add Quadrature Encoder and Pulse Counter classes. #8766

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IhorNehrutsa marked this pull request as draft June 16, 2022 21:41

tannewt pushed a commit to tannewt/circuitpython that referenced this pull request Jul 30, 2022

Merge pull request micropython#6639 from jepler/repl-ctrl-l

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readline: make ctrl-l clear screen & redraw line

IhorNehrutsa added a commit to IhorNehrutsa/micropython that referenced this pull request Sep 6, 2022

ESP32 PCNT: Add Counter and Encoder.

d99a22a

Just rebase to Version 1.19.xx from micropython#6639

IhorNehrutsa added a commit to IhorNehrutsa/micropython that referenced this pull request Oct 10, 2022

ESP32 PCNT: Add Counter and Encoder.

d7fa619

Just rebase to Version 1.19.xx from micropython#6639

IhorNehrutsa added a commit to IhorNehrutsa/micropython that referenced this pull request Nov 5, 2022

ESP32 PCNT: Add Counter and Encoder.

87e4b65

Just rebase to Version 1.19.xx from micropython#6639

IhorNehrutsa added a commit to IhorNehrutsa/micropython that referenced this pull request Feb 20, 2023

ESP32 PCNT: Add Counter and Encoder.

23b637a

Just rebase to Version 1.19.xx from micropython#6639

IhorNehrutsa added a commit to IhorNehrutsa/micropython that referenced this pull request Mar 10, 2023

ESP32 PCNT: Add Counter and Encoder.

a962be6

Just rebase to Version 1.19.xx from micropython#6639

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global: Remove the STATIC macro. #13763

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