Notes on Nyan prototype / development boxes I have built.

The NMEA 2000 connector wires have the wrong colours. I have used the correct colours of ferrules to mark them, according to the colours tabulated in NMEA 2000, except that shield is marked green.

Plastic box with:

• Pi 5. Has official fan heatsink.
• Heltec WSL V3
• INA3221. CH1: 50mR, power input. CH2: 5V converter output, voltage only.
• Lightning sensor
• RS485 - UART interface, for wind sensor / NMEA0183. Used as RS422 RX. Maybe could be used as RS485 depending on configuration of WX510.
• RS422 - USB interface, for same to talk to pi if needed, e.g. for config of WXT510.
• PoE splitter

Pi is connected as a JTAG debug probe to the Heltec.

RS422 UART board screw terminals are connected externally. Additionally, the signals and ground are connected with soldered wires to the USB RS422 interface. The colours are misleading: green is A+, red ground, black B-.

Stripboard to connect I2C bus. 470uF electrolytic on this board's 3.3V power rail, because the lightning sensor detects significantly less noise with it.

1000uF 50V caps: One on power input before anything, and one on the buck input. A ferrite with three windings of ground, input, and 5V sense line that goes to the INA3221 board are between them.

JTAG enable pin now connected to pi GPIO 4 via resistor.

470uF added to pi 5V header, and also to Heltec Vext pin.

Metal box

Pico W, Waveshare CAN and LoRa. Small 24V in to USB switcher.

Uses about 60mA from 12V (0.72W), running Nyan meshtastic.