USB serial

Connect a USB-C cable to Sentinel and open a serial monitor (e.g. PlatformIO pio device monitor, or any terminal program). Type a command then press Enter.

Note

Opening the serial port from a computer resets the board (DTR/RTS signals). Commands sent during boot wait in a small buffer (64 bytes).

Boot log

The expected boot log contains identity, version, mode, and topic:

[boot] device a2cb8ff8768d fw 0.21.1 mode gateway topik sentinel/a2cb8ff8768d/...
[sensors] DS18B20 terdeteksi: 1
[sensors] t1 terikat ke 28a54dca18253061 (baru)

The MAC on the first line is Sentinel’s identity in all topics and in Celestian; the MAC also shows on the LCD (OK, Device, first screen).

Commands

Command	Function
show	display the whole effective configuration, rejected, and fw_status
status	current sensor readings (temperature per slot, inputs, power, touch buttons), active alarms, Ethernet and MQTT status
rules	the effective rules
rescan	scan the DS18B20 bus now and show unbound sensors
i2cscan	list I2C addresses that respond, and the PCF8574 / LCD addresses in use
i2cdiag	each PCF8574 address (0x20…0x27, 0x38…0x3F): probe, read, write. Living addresses ACK; if all addresses ACK, the bus has a problem (pull-ups, wiring)
out o1 on 30	turn o1 on for 30 seconds (off turns it off; seconds optional). The slot must be enabled (oN_en)
identify	buzzer and blue LED for 5 seconds
reset_config	configuration and rules return to default, connection kept, then reboot. reset_config all also resets the connection
reset_factory	factory reset, including the web password and web language. See Reset and moving racks
reboot	restart
{"key":value,…}	one JSON line = configuration (same keys as the config topic)

Example status result on a Sentinel with one bound temperature sensor and no PZEM:

{"ds18b20_found":1,"temp":{"t1":23.4},"din":{},"voltage":null,"alarm_level":0,"eth":false,"mqtt":false,"time_valid":false}

voltage: null means the PZEM is not connected or not responding. If no temperature sensor is connected, temp is empty.

Connecting to Celestian over serial

For direct mode, send one JSON line:

{"workspace":"<workspace>","channel":"<channel>","mqtt_host":"<broker>","mqtt_user":"<device ID>","mqtt_pass":"<device key>"}

Over serial, configuration is applied and stored immediately; this is also the recovery route if the connection is misconfigured. A single line may be at most 4096 characters (enough for a private CA mqtt_ca).