4-Port Isolated VE.Direct HAT
Four galvanically isolated serial ports for solar and energy devices.
The brief
Reading several Victron devices from one Raspberry Pi means several serial links, and those devices are not going to be at the same potential as the Pi. Without isolation the shared ground turns every reading into a ground-loop problem.
Four galvanically isolated channels, each with its own isolated supply, is the answer — with the isolation itself powered from the Pi’s I2C bus so four channels still fit one connector.
What we did
A Raspberry Pi HAT that adds four galvanically isolated serial ports, so a Pi can read data from Victron solar and energy devices (VE.Direct) without ground loops or voltage spikes reaching it.
- Four isolated channels: Each port has its own isolation barrier, so the four devices are electrically separate from each other and from the Pi.
- UART expansion over I2C: Two SC16IS752 dual-UART bridges with 14.7456 MHz crystals provide four serial channels over the Pi’s I2C bus. Each bridge has its own interrupt line back to the Pi.
- Digital isolation: An ADuM1201 isolator on each channel carries TX and RX across the barrier.
- Isolated power: A B0505S-1W isolated DC-DC converter per channel powers the device side, followed by an AMS1117-3.3 LDO and decoupling to give each port a clean 3.3 V supply.
- Connectors: Four JST 4-pin connectors, one per VE.Direct device, plus a 40-pin Raspberry Pi GPIO header with pass-through.
- I2C addressing and pull-ups: The two bridges use separate addresses on a shared bus, with 4.7 kΩ pull-ups.
Design details
Design summary
| CAD tool | KiCad |
|---|---|
| Overview | A Raspberry Pi HAT that adds four galvanically isolated serial ports, so a Pi can read data from Victron solar and energy devices (VE.Direct) without… |
| Four isolated channels | Each port has its own isolation barrier, so the four devices are electrically separate from… |
| UART expansion over I2C | Two SC16IS752 dual-UART bridges with 14.7456 MHz crystals provide four serial channels over… |
| Digital isolation | An ADuM1201 isolator on each channel carries TX and RX across the barrier. |
| Isolated power | A B0505S-1W isolated DC-DC converter per channel powers the device side, followed by an… |
| Connectors | Four JST 4-pin connectors, one per VE.Direct device, plus a 40-pin Raspberry Pi GPIO header… |
| I2C addressing and pull-ups | The two bridges use separate addresses on a shared bus, with 4.7 kΩ pull-ups. |
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