I didn’t understand how you got your information so I found it for myself:
I’ll be referencing the ClockworkPi mainboard schematic and the CM4 adapter board schematic. Ranges are inclusive of the start and end.
On the mainboard, the WLAN subsystem uses the GPIO pins 3-7 for basic configuration, 14-17 for UART, 18-21 for PCM, and 22-27 for SDIO. These are all wired to the SODIMM connector for the core modules. The adapter board wires the SODIMM pins to the CM4 pins like so:
- SODIMM GPIO3-5 → CM4 GPIO3-5
- SODIMM GPIO6-7 → floating
- SODIMM GPIO14-27 → floating
So the best one can do with the CM4 adapter board is mess with the enabled state of some of the radio components on the mainboard, and one would need a new adapter board to use the mainboard’s radios.
I remain unsure of the significance of the gpio35-39 from the overlay name. It would make some sense that the mentioned pins 35-39 were physical pins on the Pi 3, corresponding to Broadcom GPIO numbers (on the schematics) 19 (PCM_SYNC), 16 (UART_RTS_N), 26 (SDIO_D_2), 20 (PCM_OUT), and ground, respectively, but then that looks like a garbled mess of signal lines.