esp-idf/examples/peripherals/mcpwm/mcpwm_bdc_speed_control

Supported Targets	ESP32	ESP32-S3

MCPWM Brushed DC Motor Example

(See the README.md file in the upper level 'examples' directory for more information about examples.)

This example mainly illustrates how to drive a brushed DC motor by generating two specific PWM signals. However the PWM signals from ESP32 can't drive motors directly as the motor usually consumes high current. So an H-bridge like DRV8848 should be used to provide the needed voltage and current for brushed DC motor. To measure the speed of motor, a photoelectric encoder is used to generate the "speed feedback" signals (e.g. a pair of quadrature signal). The example uses a simple PID control approach to keep the motor speed in a constant speed. The example provides a console command line interface for user to update the PID parameters according to actual situation.

How to Use Example

Before project configuration and build, be sure to set the correct chip target using idf.py set-target <chip_name>.

Hardware Required

• A development board with any Espressif SoC which features MCPWM and PCNT peripheral (e.g., ESP32-DevKitC, ESP-WROVER-KIT, etc.)
• A USB cable for Power supply and programming
• A separate 12V power supply for brushed DC motor and H-bridge (the voltage depends on the motor model used in the example)
• A motor driving board to transfer pwm signal into driving signal
• A brushed DC motor, e.g. 25GA370
• A quadrature encoder to detect speed

Connection :

                                     Power(12V)
                                         |
                                         v
+----------------+             +--------------------+
|                |             |      H-Bridge      |
|            GND +<----------->| GND                |      +--------------+
|                |             |                    |      |              |
|  GENA_GPIO_NUM +----PWM0A--->| IN_A         OUT_A +----->|   Brushed    |
|                |             |                    |      |     DC       |
|  GENB_GPIO_NUM +----PWM0B--->| IN_B         OUT_B +----->|    Motor     |
|                |             |                    |      |              |
| ESP            |             +--------------------+      |              |
|                |                                         +------+-------+
|                |                                                |
|                |             +--------------------+             |
|         VCC3.3 +------------>| VCC    Encoder     |             |
|                |             |                    |             |
|            GND +<----------->|                    |<------------+
|                |             |                    |
|PHASEA_GPIO_NUM |<---PhaseA---+ C1                 |
|                |             |                    |
|PHASEB_GPIO_NUM |<---PhaseB---+ C2                 |
|                |             |                    |
+----------------+             +--------------------+

Build and Flash

Run idf.py -p PORT flash monitor to build, flash and monitor the project.

(To exit the serial monitor, type Ctrl-].)

See the Getting Started Guide for full steps to configure and use ESP-IDF to build projects.

Example Output

Run the example, you will see the following output log:

I (0) cpu_start: Starting scheduler on APP CPU.
configure mcpwm gpio
init mcpwm driver
init and start rotary encoder
init PID control block
init motor control timer
D (561) gptimer: new group (0) @0x3fce0a24
D (561) gptimer: new gptimer (0,0) at 0x3fce0964, resolution=1000000Hz
create motor control task
start motor control timer
D (571) gptimer: install interrupt service for timer (0,0)
install console command line

Type 'help' to get the list of commands.
Use UP/DOWN arrows to navigate through command history.
Press TAB when typing command name to auto-complete.
dc-motor>
dc-motor> help
help
  Print the list of registered commands

pid  [-p <kp>] [-i <ki>] [-d <kd>]
  Set PID parameters
       -p <kp>  Set Kp value of PID
       -i <ki>  Set Ki value of PID
       -d <kd>  Set Kd value of PID

Set PID parameters

• Command: pid -p <double> -i <double> -d <double> -t <loc/inc>
• 'p' - proportion value
• 'i' - integral value
• 'd' - differential value
• 't' - PID calculation type (locational or incremental).

mcpwm-motor> pid -p 0.8 -i 0.02 -d 0.1 -t inc
pid: kp = 0.800
pid: ki = 0.020
pid: kd = 0.100
pid: type = increment

Troubleshooting

• Make sure your ESP board and H-bridge module have been connected to the same GND panel.

For any technical queries, please open an issue on GitHub. We will get back to you soon.