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espressif,esp32-mcpwm

Vendor: Espressif Systems

Description

Espressif's Motor Control Pulse Width Modulator (MCPWM) controller Node

The MCPWM peripheral is intended for motor and power control.
It provides six PWM outputs that can be set up to operate in several topologies

ESP32 contains two MCPWM peripherals: MCPWM0 and MCPWM1

Each MCPWM peripheral has one clock divider (prescaler), three PWM timers, three PWM operators,
and a capture module.

Every PWM operator has two PWM outputs: PWMxA and PWMxB. They can work independently, in symmetric
and asymmetric configuration. MCPWMxA and MCPWMxB will share the same timer, thus having the same
operating frequency.

The driver currently always use the timer x for operator x. Timer 0 will use operator 0 for PWM0A/B.
Timer 1 will use operator 1 for PWM1A/B, and so on.

Mapping channel ID:
Channel 0 -> Timer 0, Operator 0, output PWM0A
Channel 1 -> Timer 0, Operator 0, output PWM0B
Channel 2 -> Timer 1, Operator 1, output PWM1A
Channel 3 -> Timer 1, Operator 1, output PWM1B
Channel 4 -> Timer 2, Operator 2, output PWM2A
Channel 5 -> Timer 2, Operator 2, output PWM2B
Channel 6 -> Capture 0
Channel 7 -> Capture 1
Channel 8 -> Capture 2

Example: Use PWM0A output and capture 0:

pwm_loopback_0 {
  compatible = "test-pwm-loopback";
  pwms = <&mcpwm0 0 0 PWM_POLARITY_NORMAL>, #Channel 0 -> Output PWM0A
         <&mcpwm0 6 0 PWM_POLARITY_NORMAL>; #Channel 6 -> Capture 0;
};

The mapping between the output PWMxA/B or CaptureX and GPIO is done through pinctrl:

  &mcpwm0 {
    pinctrl-0 = <&mcpwm0_default>;
    pinctrl-names = "default";
  }

The 'mcpwm0_default' node is defined inside the pinctrl node.

  &pinctrl {
    mcpwm0_default: mcpwm0_default {
      group1 {
        pinmux = <MCPWM0_OUT0A_GPIO0>,
          <MCPWM0_OUT0B_GPIO2>,
          <MCPWM0_OUT1A_GPIO4>;
        output-enable;
      };
      group2 {
        pinmux = <MCPWM0_CAP0_GPIO5>;
      };
    };
  };

Note: Check espressif,esp32-pinctrl.yaml for complete documentation regarding pinctrl.

Use the prescale-timerX property to configure the timers:

  &mcpwm0 {
    pinctrl-0 = <&mcpwm0_default>;
    pinctrl-names = "default";
    prescale = <255>;
    prescale-timer0 = <103>;
    prescale-timer1 = <0>;
    prescale-timer2 = <255>;
    status = "okay";
  };

Properties

Properties not inherited from the base binding file.

Name

Type

Details

prescale

int

8 bit timer prescale for the global clock.
Period of PWM_clk = 6.25ns * (PWM_CLK_PRESCALE + 1).

This property is required.

#pwm-cells

int

Number of items to expect in a pwm specifier

This property is required.

Constant value: 3

prescale-timer0

int

8 bit timer prescale for timer 0.
Period of PT0_clk = Period of PWM_clk * (PWM_TIMER0_PRESCALE + 1).

prescale-timer1

int

8 bit timer prescale for timer 1.
Period of PT1_clk = Period of PWM_clk * (PWM_TIMER1_PRESCALE + 1).

prescale-timer2

int

8 bit timer prescale for timer 2.
Period of PT2_clk = Period of PWM_clk * (PWM_TIMER2_PRESCALE + 1).

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.

Specifier cell names

  • pwm cells: channel, period, flags