DD3 LoRa Bridge Raspi Debugger

Headless Raspberry Pi Zero W project:

WiFi client or fallback AP (serial / serialserial)
Web portal (http://192.168.4.1/ in AP mode)
ESP32 USB serial bridge with live SSE stream and daily log files (/home/pi/xxx_YYYY-MM-DD_HH-MM-SS.log)
Stable symlink to active log (/home/pi/xxx.log)
RTC boot restore + NTP sync + RTC write-back
Autostart via systemd

Current State

Current implementation status:

Boot flow restores system time from RTC (hwclock -s) before starting logging.
If WLAN + internet is unavailable, AP fallback starts on wlan0:
- SSID: serial
- Password: serialserial
- AP IP: 192.168.4.1/24
- DHCP range: 192.168.4.10 to 192.168.4.200
Web portal is available on port 80:
- / WiFi scan + connect UI
- /serial live serial console (SSE via /events/serial)
ESP32 serial bridge:
- Auto-detects /dev/ttyUSB*, /dev/ttyACM*, /dev/serial/by-id/*
- Reconnects automatically on unplug/replug
- Daily log rollover at midnight with datetime filename
Once internet is available, NTP sync runs and writes corrected time back to RTC (hwclock -w).

Runtime check commands:

systemctl status serial-bridge
journalctl -u serial-bridge -f
ip a show wlan0
ls -l /home/pi/xxx.log /home/pi/xxx_*.log
sudo hwclock -r

Use I2C1 pins on the 40-pin header:

RTC module pin	Raspberry Pi pin	BCM GPIO	Notes
`VCC`	`Pin 1`	3V3	Use 3.3V
`GND`	`Pin 6`	GND	Common ground
`SDA`	`Pin 3`	GPIO2 (`SDA1`)	I2C data
`SCL`	`Pin 5`	GPIO3 (`SCL1`)	I2C clock

Minimal pin marker (header top):

Pin 1 (3V3)   Pin 2 (5V)
Pin 3 (SDA1)  Pin 4 (5V)
Pin 5 (SCL1)  Pin 6 (GND)

Enable I2C + RTC overlay (example DS3231):

sudo raspi-config nonint do_i2c 0
echo 'dtoverlay=i2c-rtc,ds3231' | sudo tee -a /boot/firmware/config.txt
sudo reboot

Verify:

ls -l /dev/rtc0
sudo i2cdetect -y 1
sudo hwclock -r

chmod +x install.sh
sudo ./install.sh

Then reboot:

sudo reboot