MCPWM persists state after cleanup (IDFGH-11895)

[RemiNV]

Answers checklist.

• I have read the documentation ESP-IDF Programming Guide and the issue is not addressed there.
• I have updated my IDF branch (master or release) to the latest version and checked that the issue is present there.
• I have searched the issue tracker for a similar issue and not found a similar issue.

IDF version.

v5.3-dev-1353-gb3f7e2c8a4

Espressif SoC revision.

ESP32-H2 (revision v0.1)

Operating System used.

Linux

How did you build your project?

VS Code IDE

If you are using Windows, please specify command line type.

None

Development Kit.

ESP32-H2-DevKitM-1

Power Supply used.

USB

What is the expected behavior?

After setting up MCPWM (timer, operator, comparator, generator) as in the mcpwm servo example, then cleaning up each item with mcpwm_del_X, the procedure can be repeated to control another device on a different pin.

What is the actual behavior?

After setting up MCPWM (timer, operator, comparator, generator) as in the mcpwm servo example, then cleaning up each item with mcpwm_del_X, if another set of (timer, operator, comparator, generator) is recreated to control another servo on a different pin, the first servo will also be affected.

Steps to reproduce.

Modify mcpwm_servo_control_example_main.c with the following code. This sets up MCPWM to move a servo on pin 10, waits for a second, and cleans up the (timer, operator, comparator, generator). Then it waits for 5 seconds, and does the same thing for a servo on pin 11.

Expected behavior:

• First servo moves
• 6 seconds wait
• Second servo moves
• 6 seconds wait
• First servo moves ...

Actual behavior:

• First servo moves
• 6 seconds wait
• Both servos move
• 12 seconds wait
• Both servos move
• 12 seconds wait ...

/*
 * SPDX-FileCopyrightText: 2022-2023 Espressif Systems (Shanghai) CO LTD
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "esp_log.h"
#include "driver/mcpwm_prelude.h"

static const char *TAG = "example";

// Please consult the datasheet of your servo before changing the following parameters
#define SERVO_MIN_PULSEWIDTH_US 400  // Minimum pulse width in microsecond
#define SERVO_MAX_PULSEWIDTH_US 2600  // Maximum pulse width in microsecond
#define SERVO_MIN_DEGREE        -130   // Minimum angle
#define SERVO_MAX_DEGREE        130    // Maximum angle

#define SERVO_TIMEBASE_RESOLUTION_HZ 1000000  // 1MHz, 1us per tick
#define SERVO_TIMEBASE_PERIOD        20000    // 20000 ticks, 20ms

#define GPIO_SERVO_1 10
#define GPIO_SERVO_2 11

static inline uint32_t example_angle_to_compare(int angle)
{
    return (angle - SERVO_MIN_DEGREE) * (SERVO_MAX_PULSEWIDTH_US - SERVO_MIN_PULSEWIDTH_US) / (SERVO_MAX_DEGREE - SERVO_MIN_DEGREE) + SERVO_MIN_PULSEWIDTH_US;
}

void move_servo_and_cleanup(int init_angle, int gpio)
{
    ESP_LOGI(TAG, "Create timer and operator");
    mcpwm_timer_handle_t timer = NULL;
    mcpwm_timer_config_t timer_config = {
        .group_id = 0,
        .clk_src = MCPWM_TIMER_CLK_SRC_DEFAULT,
        .resolution_hz = SERVO_TIMEBASE_RESOLUTION_HZ,
        .period_ticks = SERVO_TIMEBASE_PERIOD,
        .count_mode = MCPWM_TIMER_COUNT_MODE_UP,
    };
    ESP_ERROR_CHECK(mcpwm_new_timer(&timer_config, &timer));

    mcpwm_oper_handle_t oper = NULL;
    mcpwm_operator_config_t operator_config = {
        .group_id = 0, // operator must be in the same group to the timer
    };
    ESP_ERROR_CHECK(mcpwm_new_operator(&operator_config, &oper));

    ESP_LOGI(TAG, "Connect timer and operator");
    ESP_ERROR_CHECK(mcpwm_operator_connect_timer(oper, timer));

    ESP_LOGI(TAG, "Create comparator and generator from the operator");
    mcpwm_cmpr_handle_t comparator = NULL;
    mcpwm_comparator_config_t comparator_config = {
        .flags.update_cmp_on_tez = true,
    };
    ESP_ERROR_CHECK(mcpwm_new_comparator(oper, &comparator_config, &comparator));

    mcpwm_gen_handle_t generator = NULL;
    mcpwm_generator_config_t generator_config = {
        .gen_gpio_num = gpio,
    };
    ESP_ERROR_CHECK(mcpwm_new_generator(oper, &generator_config, &generator));

    // set the initial compare value
    ESP_ERROR_CHECK(mcpwm_comparator_set_compare_value(comparator, example_angle_to_compare(init_angle)));

    ESP_LOGI(TAG, "Set generator action on timer and compare event");
    // go high on counter empty
    ESP_ERROR_CHECK(mcpwm_generator_set_action_on_timer_event(generator,
                    MCPWM_GEN_TIMER_EVENT_ACTION(MCPWM_TIMER_DIRECTION_UP, MCPWM_TIMER_EVENT_EMPTY, MCPWM_GEN_ACTION_HIGH)));
    // go low on compare threshold
    ESP_ERROR_CHECK(mcpwm_generator_set_action_on_compare_event(generator,
                    MCPWM_GEN_COMPARE_EVENT_ACTION(MCPWM_TIMER_DIRECTION_UP, comparator, MCPWM_GEN_ACTION_LOW)));
 
    ESP_LOGI(TAG, "Enable and start timer");
    ESP_ERROR_CHECK(mcpwm_timer_enable(timer));
    ESP_ERROR_CHECK(mcpwm_timer_start_stop(timer, MCPWM_TIMER_START_NO_STOP));

    vTaskDelay(pdMS_TO_TICKS(1000));

    ESP_ERROR_CHECK(mcpwm_del_generator(generator));
    ESP_ERROR_CHECK(mcpwm_del_comparator(comparator));
    ESP_ERROR_CHECK(mcpwm_del_operator(oper));
    ESP_ERROR_CHECK(mcpwm_timer_disable(timer));
    ESP_ERROR_CHECK(mcpwm_del_timer(timer));
}

void app_main(void)
{
    int angle = SERVO_MIN_DEGREE;
    // Move each servo in sequence
    while (1) {
        move_servo_and_cleanup(angle, GPIO_SERVO_1);
        vTaskDelay(pdMS_TO_TICKS(5000));
        move_servo_and_cleanup(angle, GPIO_SERVO_2);
        angle = -angle;
        vTaskDelay(pdMS_TO_TICKS(5000));
    }
}

Debug Logs.

No response

More Information.

It seems that there is some problem where setting up MCPWM, and cleaning it up with mcpwm_del_X, does not actually fully clean it up and it affects subsequent setups ?

[RemiNV]

I found that calling gpio_reset_pin(gpio) after deleting the timer resolves the issue, but it seems that this should be handled by deleting the generator ? Or at least be documented as a necessary cleanup step. I am also not sure whether that is the only missing cleanup, or if there is other state left.

[suda-morris]

Hi @RemiNV thanks for reporting. Yes, I also think we need to reset the GPIO in mcpwm_del_generator