interleaved_pwm

ESP-IDF component for multi-phase interleaved PWM generation using the LEDC peripheral. Instead of switching all channels simultaneously, this component distributes switching events across the PWM period, reducing input ripple and improving power integrity.

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Features

• Multi-channel phase-interleaved PWM
• Automatic even phase distribution
• Configurable dead time enforcement
• Runtime per-channel pulse width control
• Automatic LEDC timer resolution selection
• Cross-chip support using soc_caps
• Validation of timing constraints at creation

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Installation

Using ESP-IDF Component Manager (Recommended)

idf.py add-dependency "embedblocks/interleaved_pwm^0..1.17"

Or in your project's idf_component.yml:

dependencies:
  embedblocks/interleaved_pwm: "^0..1.17"

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How it works

The PWM period is divided into equal slots, one per channel:

slot = period / total_channels

Each channel is phase-shifted into its own slot.

Time →   0        5000      10000     15000     20000  (µs)
         |---------|---------|---------|---------|
CH0      [  ON  ]__|
CH1               [  ON  ]__|
CH2                         [  ON  ]__|
CH3                                   [  ON  ]__|

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Dead Time Constraint

pulse_width + dead_time ≤ slot

If violated, creation fails.

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Frequency and Resolution

• Resolution is auto-selected based on:
  • frequency
  • number of channels
• Guarantees ≥5% granularity per slot
• Maximum resolution: 13 bits

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Chip Support

Chip	Status
ESP32	✅ Tested
ESP32-S2	⚠️ Expected to work
ESP32-S3	⚠️ Expected to work
ESP32-C3	⚠️ Expected to work

The component uses soc/soc_caps.h and targets the LEDC low-speed mode, making it portable across ESP-IDF supported chips.

However, only ESP32 has been fully validated so far.

API

Create

esp_err_t interleavedPWMCreate(
    interleaved_pwm_config_t *config,
    interleaved_pwm_handle_t **out_handle);

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Control

PWM_START(handle);
PWM_STOP(handle);
PWM_DESTROY(&handle);
PWM_SET_WIDTH(handle, channel, width);

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Usage Example

#include "interleaved_pwm.h"

static uint8_t gpio_list[4] = {5, 18, 22, 23};
static uint32_t widths[4]   = {2000, 2000, 2000, 2000};

interleaved_pwm_handle_t *pwm = NULL;
interleaved_pwm_config_t config = {
    .gpio_no      = gpio_list,
    .pulse_widths = widths,
    .total_gpio   = 4,
    .dead_time    = 1000,
    .frequency    = 50
};

ESP_ERROR_CHECK(interleavedPWMCreate(&config, &pwm));
PWM_START(pwm);
PWM_SET_WIDTH(pwm, 0, 3000);
PWM_STOP(pwm);
PWM_DESTROY(&pwm);

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Limitations

• All channels may not be correct on 1-2 cycle after start because of LEDC limitation
• Single instance per application in the current release
• Timer 0 is always used — not configurable
• 13-bit resolution cap (sufficient for all supported chips)
• No dynamic channel reallocation after creation

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Examples

The component includes two examples demonstrating typical usage patterns.

Example	Description
simple	Minimal setup of a multi-channel interleaved PWM instance. Shows basic creation, start, and steady-state operation.
ramp	Demonstrates runtime pulse width updates using a ramp pattern across channels. Useful for observing dynamic behaviour and transient response.

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Running an example

1. Navigate to the example directory:

cd examples/simple
idf.py build flash monitor


# License
MIT License