File	Description
`boot.py`	WiFi connect + OTA trigger
`ota.py`	Gitea API poller for OTA updates
`gaugemqtt.py`	Main MQTT controller
`gauge.py`	Stepper driver for VID28/BKA30D/X25 gauges
`config.json`	Configuration (create from `config.example.json`)
`config.example.json`	Template with all options

Deployment

# First time: upload via USB
ampy --port /dev/ttyUSB0 put boot.py
ampy --port /dev/ttyUSB0 put ota.py
ampy --port /dev/ttyUSB0 put gaugemqtt.py
ampy --port /dev/ttyUSB0 put gauge.py
ampy --port /dev/ttyUSB0 put config.json
ampy --port /dev/ttyUSB0 put lib/gauge.py /lib/gauge.py

# Monitor serial output
minicom -D /dev/ttyUSB0 -b 115200

MQTT Topics

All topics are prefixed with mqtt_prefix:

Topic	Direction	Description
`/set`	←	Target value from HA
`/state`	→	Current value
`/status`	→	`online`/`offline`
`/zero`	←	Trigger zero calibration
`/led/red/set`	←	`ON`/`OFF`
`/led/green/set`	←	`ON`/`OFF`
`/led/backlight/set`	←	Brightness 0-100

Configuration

Copy config.example.json to config.json and edit:

WiFi

Key	Default	Description
`wifi_ssid`	—	WiFi network name
`wifi_password`	—	WiFi password

MQTT

Key	Default	Description
`mqtt_broker`	—	Broker IP/hostname
`mqtt_port`	1883	Broker port
`mqtt_user`	—	MQTT username
`mqtt_password`	—	MQTT password
`mqtt_client_id`	—	Unique client ID
`mqtt_prefix`	—	Topic prefix for all MQTT messages

Gauge

Key	Default	Description
`gauge_pins`	`[12, 13, 26, 27]`	GPIO pins (IN1, IN2, IN3, IN4)
`gauge_min`	0	Minimum value
`gauge_max`	7300	Maximum value
`gauge_pulse`	4	Pulse width in milliseconds
`gauge_half_step`	false	Use 8-phase half-step mode (1200 steps, smoother)
`smooth_step_ms`	50	Smooth movement interval
`idle_release_ms`	3000	Release coils after idle (ms)
`rezero_interval_ms`	3600000	Auto-rezero interval (ms, default 1hr)

LEDs

Key	Default	Description
`led_red_pin`	33	Red LED GPIO pin
`led_green_pin`	32	Green LED GPIO pin
`led_bl_pin`	23	Backlight PWM GPIO pin

Home Assistant Discovery

Key	Default	Description
`device_name`	"Selsyn 1"	Device name in HA
`device_model`	"Chernobyl Selsyn-inspired gauge"	Device model
`device_manufacturer`	"AdeBaumann"	Device manufacturer
`device_area`	"Control Panels"	Suggested area in HA
`gauge_entity_name`	"Selsyn 1 Power"	Gauge entity name
`gauge_unit`	"W"	Unit of measurement for gauge
`red_led_entity_name`	"Selsyn 1 Red LED"	Red LED entity name
`green_led_entity_name`	"Selsyn 1 Green LED"	Green LED entity name
`backlight_entity_name`	"Selsyn 1 Backlight"	Backlight entity name
`backlight_unit`	"%"	Unit for backlight

Timing

Key	Default	Description
`heartbeat_ms`	10000	State publish interval (ms)