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mcpwm: update servo control example
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morris
suda-morris
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| Supported Targets | ESP32 |
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| ----------------- | ----- |
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| Supported Targets | ESP32 | ESP32-S3 |
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| ----------------- | ----- | -------- |
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# MCPWM RC Servo Control Example
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# MCPWM servo motor control Example
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(See the README.md file in the upper level 'examples' directory for more information about examples.)
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This example will show you how to use MCPWM module to control servo motor
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Assign pulse width range and the maximum degree, accordingly the servo will move from 0 to maximum degree continuously
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This example illustrates how to drive a typical [RC Servo](https://en.wikipedia.org/wiki/Servo_(radio_control)) by sending a PWM signal using the MCPWM driver. The PWM pulse has a frequency of 50Hz (period of 20ms), and the active-high time (which controls the rotation) ranges from 1ms to 2ms with 1.5ms always being center of range.
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## Step 1: Pin assignment
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* GPIO18 is assigned as the MCPWM signal for servo motor
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## How to Use Example
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### Hardware Required
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* A development board with any Espressif SoC which features MCPWM peripheral (e.g., ESP32-DevKitC, ESP-WROVER-KIT, etc.)
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* A USB cable for Power supply and programming
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* A RC servo motor, e.g. [SG90](http://www.ee.ic.ac.uk/pcheung/teaching/DE1_EE/stores/sg90_datasheet.pdf)
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Connection :
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```
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+-------+ +-----------------+
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| | | |
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| +-+ GPIO18++ PWM(Orange) +----------+ |
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| ESP |---5V------+ Vcc(Red) +--------------| Servo Motor |
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| +---------+ GND(Brown) +----------+ |
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| | | |
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+-------+ +-----------------+
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```
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### Build and Flash
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Run `idf.py -p PORT flash monitor` to build, flash and monitor the project.
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(To exit the serial monitor, type ``Ctrl-]``.)
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See the [Getting Started Guide](https://docs.espressif.com/projects/esp-idf/en/latest/get-started/index.html) for full steps to configure and use ESP-IDF to build projects.
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## Step 2: Connection
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* connect GPIO18 with servo pwm signal
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* other two wires of servo motor are VCC and GND
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## Example Output
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Run the example, you will see the following output log:
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## Step 3: Initialize MCPWM
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* You need to set the frequency(generally 50 Hz) and duty cycle of MCPWM timer
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* You need to set the MCPWM channel you want to use, and bind the channel with one of the timers
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```
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...
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I (0) cpu_start: Starting scheduler on APP CPU.
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I (349) example: Angle of rotation: -90
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I (449) example: Angle of rotation: -89
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I (549) example: Angle of rotation: -88
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I (649) example: Angle of rotation: -87
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I (749) example: Angle of rotation: -86
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...
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```
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The servo will rotate from -90 degree to 90 degree, and then turn back again.
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## Troubleshooting
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Note that, some kind of servo might need a higher current supply than the development board usually can provide. It's recommended to power the servo separately.
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For any technical queries, please open an [issue] (https://github.com/espressif/esp-idf/issues) on GitHub. We will get back to you soon.
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@ -1,2 +1,2 @@
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idf_component_register(SRCS "mcpwm_servo_control_example.c"
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idf_component_register(SRCS "mcpwm_servo_control_example_main.c"
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INCLUDE_DIRS ".")
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@ -1,77 +0,0 @@
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/* servo motor control example
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This example code is in the Public Domain (or CC0 licensed, at your option.)
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Unless required by applicable law or agreed to in writing, this
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software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
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CONDITIONS OF ANY KIND, either express or implied.
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*/
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#include <stdio.h>
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#include "freertos/FreeRTOS.h"
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#include "freertos/task.h"
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#include "esp_attr.h"
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#include "driver/mcpwm.h"
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#include "soc/mcpwm_periph.h"
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//You can get these value from the datasheet of servo you use, in general pulse width varies between 1000 to 2000 mocrosecond
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#define SERVO_MIN_PULSEWIDTH 1000 //Minimum pulse width in microsecond
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#define SERVO_MAX_PULSEWIDTH 2000 //Maximum pulse width in microsecond
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#define SERVO_MAX_DEGREE 90 //Maximum angle in degree upto which servo can rotate
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static void mcpwm_example_gpio_initialize(void)
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{
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printf("initializing mcpwm servo control gpio......\n");
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mcpwm_gpio_init(MCPWM_UNIT_0, MCPWM0A, 18); //Set GPIO 18 as PWM0A, to which servo is connected
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}
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/**
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* @brief Use this function to calcute pulse width for per degree rotation
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*
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* @param degree_of_rotation the angle in degree to which servo has to rotate
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*
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* @return
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* - calculated pulse width
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*/
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static uint32_t servo_per_degree_init(uint32_t degree_of_rotation)
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{
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uint32_t cal_pulsewidth = 0;
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cal_pulsewidth = (SERVO_MIN_PULSEWIDTH + (((SERVO_MAX_PULSEWIDTH - SERVO_MIN_PULSEWIDTH) * (degree_of_rotation)) / (SERVO_MAX_DEGREE)));
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return cal_pulsewidth;
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}
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/**
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* @brief Configure MCPWM module
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*/
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void mcpwm_example_servo_control(void *arg)
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{
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uint32_t angle, count;
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//1. mcpwm gpio initialization
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mcpwm_example_gpio_initialize();
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//2. initial mcpwm configuration
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printf("Configuring Initial Parameters of mcpwm......\n");
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mcpwm_config_t pwm_config;
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pwm_config.frequency = 50; //frequency = 50Hz, i.e. for every servo motor time period should be 20ms
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pwm_config.cmpr_a = 0; //duty cycle of PWMxA = 0
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pwm_config.cmpr_b = 0; //duty cycle of PWMxb = 0
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pwm_config.counter_mode = MCPWM_UP_COUNTER;
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pwm_config.duty_mode = MCPWM_DUTY_MODE_0;
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mcpwm_init(MCPWM_UNIT_0, MCPWM_TIMER_0, &pwm_config); //Configure PWM0A & PWM0B with above settings
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while (1) {
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for (count = 0; count < SERVO_MAX_DEGREE; count++) {
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printf("Angle of rotation: %d\n", count);
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angle = servo_per_degree_init(count);
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printf("pulse width: %dus\n", angle);
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mcpwm_set_duty_in_us(MCPWM_UNIT_0, MCPWM_TIMER_0, MCPWM_OPR_A, angle);
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vTaskDelay(10); //Add delay, since it takes time for servo to rotate, generally 100ms/60degree rotation at 5V
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}
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}
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}
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void app_main(void)
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{
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printf("Testing servo motor.......\n");
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xTaskCreate(mcpwm_example_servo_control, "mcpwm_example_servo_control", 4096, NULL, 5, NULL);
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}
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@ -0,0 +1,47 @@
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/* Servo Motor control example
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This example code is in the Public Domain (or CC0 licensed, at your option.)
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Unless required by applicable law or agreed to in writing, this
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software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
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CONDITIONS OF ANY KIND, either express or implied.
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*/
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#include "freertos/FreeRTOS.h"
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#include "freertos/task.h"
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#include "esp_log.h"
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#include "driver/mcpwm.h"
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static const char *TAG = "example";
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// You can get these value from the datasheet of servo you use, in general pulse width varies between 1000 to 2000 mocrosecond
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#define SERVO_MIN_PULSEWIDTH_US (1000) // Minimum pulse width in microsecond
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#define SERVO_MAX_PULSEWIDTH_US (2000) // Maximum pulse width in microsecond
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#define SERVO_MAX_DEGREE (90) // Maximum angle in degree upto which servo can rotate
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#define SERVO_PULSE_GPIO (18) // GPIO connects to the PWM signal line
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static inline uint32_t example_convert_servo_angle_to_duty_us(int angle)
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{
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return (angle + SERVO_MAX_DEGREE) * (SERVO_MAX_PULSEWIDTH_US - SERVO_MIN_PULSEWIDTH_US) / (2 * SERVO_MAX_DEGREE) + SERVO_MIN_PULSEWIDTH_US;
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}
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void app_main(void)
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{
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mcpwm_gpio_init(MCPWM_UNIT_0, MCPWM0A, SERVO_PULSE_GPIO); // To drive a RC servo, one MCPWM generator is enough
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mcpwm_config_t pwm_config = {
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.frequency = 50, // frequency = 50Hz, i.e. for every servo motor time period should be 20ms
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.cmpr_a = 0, // duty cycle of PWMxA = 0
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.counter_mode = MCPWM_UP_COUNTER,
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.duty_mode = MCPWM_DUTY_MODE_0,
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};
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mcpwm_init(MCPWM_UNIT_0, MCPWM_TIMER_0, &pwm_config);
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while (1) {
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for (int angle = -SERVO_MAX_DEGREE; angle < SERVO_MAX_DEGREE; angle++) {
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ESP_LOGI(TAG, "Angle of rotation: %d", angle);
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ESP_ERROR_CHECK(mcpwm_set_duty_in_us(MCPWM_UNIT_0, MCPWM_TIMER_0, MCPWM_OPR_A, example_convert_servo_angle_to_duty_us(angle)));
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vTaskDelay(pdMS_TO_TICKS(100)); //Add delay, since it takes time for servo to rotate, generally 100ms/60degree rotation under 5V power supply
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}
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}
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}
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