Servo control unexpected movement on boot - *sometimes*

ESPHome
1

I have a small esphome project that uses an ESP8266 to move a servo. I’m running the project from battery, so also using deep_sleep and controlling the required movement via MQTT commands. I’m using ESPHome version 2023.10.1

This is generally working well. The issue I’m finding is that occasionally (maybe 1 in 10 boots), the servo appears to return to a neutral/home position, before restoring back to the last retained message value. What could the reason for this be? If I disable the deep_sleep, then the servo never moves unless commanded - so it definitely appears to be a boot related issue.

my config -

esphome:
  name: $device_name

esp8266:
  board: d1_mini

ota:
  password: !secret ota_password

mqtt:
  broker: $mqtt_broker
  id: mqtt_client
  birth_message:
    topic: 'nope'
    payload: online
  will_message:
    topic: 'disabled'
    payload: offline
  topic_prefix: homeassistant/$device_name
  on_message:
    - topic: homeassistant/ota_mode
      payload: 'ON'
      then:
        - logger.log: 
            format: "OTA mode ON - battery usage elevated"
            level: INFO
        - deep_sleep.prevent: deep_sleep_1
    - topic: homeassistant/ota_mode
      payload: 'OFF'
      then:
        - logger.log: 
            format: "OTA mode OFF - deep sleep now available"
            level: INFO
        - deep_sleep.allow: deep_sleep_1
    - topic: homeassistant/$device_name/number/catdoorposition/command
      then:
        - number.set:
            id: catdoor_position
            value: !lambda |-
              return stof(x);

wifi:
  ssid: !secret wifi_ssid
  password: !secret wifi_password
  # update this to override OTA update target
  use_address: $static_ip_address
  fast_connect: true
  manual_ip:
    static_ip: $static_ip_address
    gateway: $static_ip_gateway
    subnet: $static_ip_subnet

  # Enable fallback hotspot (captive portal) in case wifi connection fails
  ap:
    ssid: !secret fallback_wifi_ssid
    password: !secret fallback_wifi_password

http_request:
  useragent: esphome/$device_name
  timeout: 2s

# Enable logging
logger:
  level: $log_level

output:
  - platform: esp8266_pwm
    id: pwm_output
    pin: $gpio_servo_pin
    frequency: 50 Hz

servo:
  - id: catdoor_servo
    output: pwm_output
    auto_detach_time: 2s
    max_level: 12.8%

number:
  - platform: template
    id: catdoor_position
    name: "catdoorposition"
    min_value: -100
    max_value: 100
    step: 1
    optimistic: true
    set_action:
      then:
        - servo.write:
            id: catdoor_servo
            level: !lambda 'return x / 100.0;'

sensor:
  - platform: adc
    pin: VCC
    name: "VCC Voltage"

deep_sleep:
  id: deep_sleep_1
  run_duration: $sleep_duration_awake
  sleep_duration: $sleep_duration
3

You can try the “early pin init” config in esphome to see if it changes the behavior.