espressif,esp32-pcnt

Overview

Name:

espressif,esp32-pcnt

Vendor:

Espressif Systems

Used in:

List of boards using this compatible

Driver:

drivers/sensor/espressif/pcnt_esp32/pcnt_esp32.c

Description

ESP32 Pulse Counter (PCNT)

The pulse counter module is designed to count the number of
rising and/or falling edges of an input signal.

The original ESP32 has 8 independent counting units (0 to 7). ESP32-S2,
ESP32-S3, ESP32-C5, ESP32-C6, ESP32-H2 and ESP32-P4 each have 4 units
(0 to 3).

Each pulse counter unit has a 16-bit signed counter register.

Each unit has two independent channel: ch0 and ch1 that can be configured
to either increment or decrement the counter.

Each channel has two inputs: a signal input that accepts signal edges
to be detected, as well as a control input that can be used to enable
or disable the signal input.

Each pulse counter unit also features a filter on each of the four inputs,
adding the option to ignore short glitches in the signals.

By combining the usage of both signal and control inputs, a PCNT unit can
act as a quadrature decoder.

The mapping between signal and control input and the pin is done through pinctrl.
Check espressif,esp32-pinctrl.yaml for complete documentation regarding pinctrl.

Examples

/* Use PCNT to read a rotary-encoder */
&pinctrl {
    pcnt_default: pcnt_default {
        group1 {
            pinmux = <PCNT0_CH0SIG_GPIO14>,
                    <PCNT0_CH0CTRL_GPIO15>;
            bias-pull-up;
        };
    };
};
&pcnt {
  pinctrl-0 = <&pcnt_default>;
  pinctrl-names = "default";
  status = "okay";
  #address-cells = <1>;
  #size-cells = <0>;
  unit0@0 {
    reg = <0>;
    #address-cells = <1>;
    #size-cells = <0>;
    filter = <100>;
    channelA@0 {
        reg = <0>;
        sig-pos-mode = <2>;
        sig-neg-mode = <1>;
        ctrl-h-mode = <0>;
        ctrl-l-mode = <1>;
    };
  };
};

Properties

Top level properties

These property descriptions apply to “espressif,esp32-pcnt” nodes themselves. This page also describes child node properties in the following sections.

Node specific propertiesDeprecated node specific propertiesBase properties

Properties not inherited from the base binding file.

Name	Type	Details
friendly-name	string	Human readable string describing the sensor. It can be used to distinguish multiple instances of the same model (e.g., lid accelerometer vs. base accelerometer in a laptop) to a host operating system. This property is defined in the Generic Sensor Property Usages of the HID Usage Tables specification (https://usb.org/sites/default/files/hut1_3_0.pdf, section 22.5).
pinctrl-0	phandles	Pin configuration/s for the first state. Content is specific to the selected pin controller driver implementation.
pinctrl-1	phandles	Pin configuration/s for the second state. See pinctrl-0.
pinctrl-2	phandles	Pin configuration/s for the third state. See pinctrl-0.
pinctrl-3	phandles	Pin configuration/s for the fourth state. See pinctrl-0.
pinctrl-4	phandles	Pin configuration/s for the fifth state. See pinctrl-0.
pinctrl-names	string-array	Names for the provided states. The number of names needs to match the number of states.

Child node properties

Name	Type	Details
reg	int	The PCNT unit index. The ESP32 has 8 PCNT units. ESP32S2/S3 have 4 PCNT units. This property is required. Legal values: 0, 1, 2, 3, 4, 5, 6, 7 See Important properties for more information.
filter	int	Glitch filter threshold in APB clock cycles (typical APB = 80 MHz so 1 cycle = 12.5 ns). Pulses shorter than this value are ignored. Maximum 1023; driver clamps higher values. Omit or set to 0 to disable the filter.
counts-per-revolution	int	Number of encoder counts per full mechanical revolution. When non-zero, SENSOR_CHAN_ROTATION returns degrees [0..360). When zero (default), SENSOR_CHAN_ROTATION returns raw counts (legacy behavior, preserved for backward compatibility). SENSOR_CHAN_ENCODER_COUNT always returns raw counts.
high-limit	int	Upper watchpoint. When the counter reaches this value the PCNT hardware auto-resets the counter to zero and raises a HIGH_LIMIT event. Value must fit in int16_t (range -32768..32767). Omit to disable the high-limit watchpoint.
low-limit	int	Lower watchpoint. When the counter reaches this value the PCNT hardware auto-resets the counter to zero and raises a LOW_LIMIT event. Value must fit in int16_t (range -32768..32767). Omit to disable the low-limit watchpoint.
zero-cross-event	boolean	When present, the PCNT hardware raises a ZERO_CROSS event whenever the counter crosses zero. The event fires a threshold trigger at counter index 0 on the unit.

Grandchild node properties

Name	Type	Details
reg	int	The PCNT channel index. This property is required. Legal values: 0, 1 See Important properties for more information.
sig-pos-mode	int	Define what to do on the positive edge of pulse input. 0 (Default) - Inhibit counter (counter value will not change in this condition). 1 - Increase counter value. 2 - Decrease counter value. Legal values: 0, 1, 2
sig-neg-mode	int	Define what to do on the negative edge of pulse input. 0 (Default) - Inhibit counter (counter value will not change in this condition). 1 - Increase counter value. 2 - Decrease counter value. Legal values: 0, 1, 2
ctrl-h-mode	int	Define what to do when the control input is high. 0 (Default) - Don't change counter mode. 1 - Invert counter mode(increase -> decrease, decrease -> increase). 2 - Control mode: Inhibit counter (counter value will not change in this condition). Legal values: 0, 1, 2
ctrl-l-mode	int	Define what to do when the control input is low. 0 (Default) - Don't change counter mode. 1 - Invert counter mode(increase -> decrease, decrease -> increase). 2 - Control mode: Inhibit counter (counter value will not change in this condition). Legal values: 0, 1, 2