esp-idf/examples/peripherals/pcnt/README.md

PCNT Example

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

This example uses the pulse counter module (PCNT) to count the rising edges of the PWM pulses generated by the LED Controller module (LEDC).

How to use example

Hardware Required

• A development board with ESP32 SoC (e.g., ESP32-DevKitC, ESP-WROVER-KIT, etc.)
• A USB cable for power supply and programming

Pin connection:

• GPIO4 is the default output GPIO of the 1 Hz pulse generator.
• GPIO18 is the default pulse input GPIO. We need to short GPIO4 and GPIO18.
• GPIO5 is the default control signal, which can be left floating with internal pull up, or connected to Ground (If GPIO5 is left floating, the value of counter increases with the rising edges of the PWM pulses. If GPIO15 is connected to Ground, the value decreases).

Configure the project

make menuconfig

• Set serial port under Serial Flasher Options.

Build and Flash

Build the project and flash it to the board, then run monitor tool to view serial output:

make -j4 flash monitor

(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 this example, and you can see the following output log on the serial monitor: (Here, GPIO5 is connected to Ground)

Current counter value :-1
Current counter value :-2
Current counter value :-3
Current counter value :-4
Event PCNT unit[0]; cnt: -5
THRES0 EVT
Current counter value :-5
Current counter value :-6
Current counter value :-7
Current counter value :-8
Current counter value :-9
Event PCNT unit[0]; cnt: 0
L_LIM EVT
ZERO EVT
Current counter value :0
Current counter value :-1
...

Troubleshooting

• program upload failure

  • Hardware connection is not correct: run idf.py monitor, and reboot your board to see if there are any output logs.
  • The baud rate for downloading is too high: lower your baud rate in the menuconfig menu, and try again.

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