Supported Targets	ESP32-C6

This example demonstrates how to program the ULP Core coprocessor to count pulses on an IO while the main CPUs are either running some other code or are in deep sleep. See the README.md file in the upper level 'examples' directory for more information about examples.

At runtime, the main code running on the ESP (found in lp_core_pulse_counter_example_main.c) loads ULP program into the RTC_SLOW_MEM memory region using ulp_lp_core_load_binary function. Main code configures the ULP program by setting up values of some variables and then starts it using ulp_lp_core_run. Once the ULP program is started, it monitors the IO pin for pulses.

When the ULP program finds an edge in the input signal, it performs debouncing and increments the variable maintaining the total edge count. Once the edge count reaches certain value, ULP triggers wake up from deep sleep. Note that the ULP program keeps running and monitoring the input signal even when the SoC is woken up.

Hardware Required

To run this example, you should have a development board based on any of the chips listed in the supported targets table at the top and a host machine with a serial input connection.

Pin Assignment:

Note: The following pin assignments are used by default.

	Uart Tx	Pulse Count Input
ESP32-C6	GPIO5	GPIO6
Host machine	Rx	N/A

Example Output

The log output from the serial monitor connected to the main core should indicate that the LP core and the LP UART peripheral have been successfully initialized. The main CPU would then enter deep sleep mode.

Using pin 6 as pulse counter input
ULP will wake up processor after every 10 pulses
Not a ULP wakeup, initializing it!
Entering in deep sleep
...
rst:0x5 (SLEEP_WAKEUP),boot:0xc (SPI_FAST_FLASH_BOOT)
...
ULP woke up the main CPU!
Pulse count: 11
Entering in deep sleep

The log output from the serial monitor connected to the LP core should display output as below -

LP Core pulse counter started
Pulse count: 10, wake-up main CPU

Troubleshooting

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