FemtoLCC is a four-layer accessory node for model railroad layouts. It joins an LCC/OpenLCB network over CAN, takes an opto-isolated DCC feed from the layout, and drives four independent block outputs from a single board. The whole thing fits on a 3.00 × 3.75 in board.
What is on the board
An ESP32-C6-WROOM-1 module runs the node firmware, bringing Wi-Fi, BLE and 802.15.4 along with its RISC-V core. The LCC bus arrives on a standard RJ45 connector through an MCP2562 CAN transceiver, and the DCC feed passes through an HCPL-0630 dual optocoupler so the layout stays galvanically separated from the logic.
The four block outputs are driven by DRV8874 H-bridges, one per channel, fed through SN74HC253 dual 4:1 multiplexers for channel steering. An MCP23018 I²C port expander handles additional discrete I/O. Power comes in through a P-MOSFET reverse-protection path to 5 V and 3.3 V rails.
Connectors
The four block driver outputs land on Phoenix MKDS 5.08 mm terminal blocks, with the DCC and power feeds on 3.5 mm Phoenix MCV headers. Also on the board are a USB-C port, a 6-pin UART header, a PMOD socket and a 4-pin JST SH connector.
Documentation
The project documentation covers what each block on the board does, the mechanical outline with its mounting pattern and drill schedule, and what you need to get boards made. The KiCad project, fabrication pipeline and firmware are all in the public repository.