GPIO breakout via the 40-pin FPC connector
A 0.5 mm 40-pin FPC-to-DIP adapter plugged into the mainboard connector above the compute module exposes the Pi's GPIO.
What it takes
- Disassembly
- Purchase required
Difficulty 2 of 3 — moderate.
Details
The mainboard has a 40-pin FPC header carrying the compute module's GPIO. A cheap FPC-to-DIP breakout brings it out, but orientation isn't marked: one way round there is no 3.3 V or 5 V, the other way an R-01 core heated up fast. lis6502's thread works through pin mapping and continuity checks, and the same connector is what the fan and I²C boards use.
Links
Open at Forum threadRelated mods
Vitaly's open-hardware card puts an RP2040 microcontroller and a GPIO pinout in the expansion slot for sensors, hats and firmware projects.
Zucker's minimal card: a microSD slot, an internal-facing USB port and every GPIO from the PCIe-style connector broken out.
AleReb's card adds more GPIO, a camera connection and several I²C headers, built on PotatoMania's KiCad template.
Three boards that replace the stock adapter and battery board: PCIe NVMe storage, RJ45 Gigabit Ethernet and USB 3.0 (CM5), plus a PWM fan header.
The all-in-one expansion card: RTL-SDR, SX1262 LoRa, GNSS, RTC and a USB hub with internal USB-C; the adapter board adds USB 3.0 and Gigabit Ethernet.
The 2024 original: an RTL-SDR (R820T2), USB hub and real-time clock on one expansion card — the board that started the AIO line.