Esp32 pca9685 external_clock_input ledc id: extclk

ESPHome
1

Hi there,

I have a esp32 connected to a pca9685 and trying to use the pwm to control a fan that requires 22kHz pwm signal to be happy.
In Components ➔ Output Component ➔ PCA9685 it states in the example that an external clock mode is available and we are shown an example that does not work since I don’t get any pwm on the oscilloscope.

Wire connections between esp32 and pca: just clasic i2c, power (3v3,+,-) and scl & sda.
Pca9685 has external (v+) 5v connected to be transmitted to the outputs.

With internal pca9685 clock source I get a 0.02 difference which is perfect so I can confirm it’s not a hardware issue, with external_clock_input: true I get no signal on the oscilloscope.

Here is the code I use:

i2c:
  sda: 21
  scl: 22
  scan: true
  id: i2c_bus_a
  frequency: 100kHz 

# Example configuration entry with external clock enable and clock source from ESP32
pca9685:
  - id: pca9685_hub1
    external_clock_input: true
  # - address: 0x40 ## Default 0x40 - this requires setting frq manualy? - incompatible with external_clock_input
  #  frequency: 1525 ## !!! Sets FRQ for all pins - does not work with external_clock_input true Frequency cannot be set when using an external clock input. 24Hz to 1525.88Hz. Default 1000Hz

# Individual outputs
output:
    # generate PWM from ESP32 ledc
    ## frequency range of LEDC is from 10Hz to 40MHz - however, higher frequencies require a smaller bit depth which means the output is not that accurate for frequencies above ~300kHz.
  - platform: ledc
    pin: GPIO5 ## The pin to use LEDC on. Can only be GPIO0-GPIO33.
    id: extclk 
    min_power: 0 
    max_power: 1 ## between 0.00 and 1
    #inverted: true
    frequency: 22khz ## Preffered Delta PFC1212DE pwm frequency

  - platform: pca9685
    #pca9685_id: pca9685_hub1 ## Use this if you have multiple PCA9685s you want to use at the same time.
    id: pwm_ch_0
    channel: 0 ## 0 to 15
    
fan:
  - platform: speed
    output: pwm_ch_0 ## id of the float output to use for this fan
    name: "Delta PFC1212DE"

My questions are:

  1. Is the code correct?

  2. How is the clock transmited from esp32 to pca9685? ( this is why I added 100kHz to i2c bus frequency but changed nothing on the output of pca ).

  3. What is happening with the output of GPIO5 on the ESP since I can’t see any pwm on it on the oscilloscope.

Any help would be much appreciated.

2

Any ideas on this ?