It seems like CFexpress is going to replace CFast and CF card as the new de-facto DSLR storage medium, at least for Japanese camera manufacturers. The Internet kept its mouth very shut about what this CFexpress Card actually is, with specification no where to be found.
However, piecing a few separate pieces of information together, we can make up pretty much what the specification is: it’s more-or-less M.2 with non PCI-e pins removed, with a new “INS#” pin. It’s also single sided, and utilizes a PCB edge connector.
The connector looks like this:
Here’s the pin assignment table:
| PIN | Signal | I/O Direction | Required on Media? R/O/NC | Required on Host? R/O/NC | Notes |
|---|---|---|---|---|---|
| 1 | GND | R | R | ||
| 2 | PERp1 | O | O | R | |
| 3 | PERn1 | O | O | R | |
| 4 | GND | R | R | Tie to ground if lane 1 present | |
| 5 | PETn1 | I | O | R | |
| 6 | PETp1 | I | O | R | |
| 7 | Reserved | NC | R | ||
| 8 | Reserved | NC | R | ||
| 9 | PERST# | I | R | R | |
| 10 | +3V3 | R | R | ||
| 11 | CLKREQ# | O | R | O | Active Low. Pull-up of >5kOhm on Host |
| 12 | INS# | O | R | R | Active Low. Tie to ground on media side. Pull-up of 100-200kOhm on Host |
| 13 | REFCLK- | I | R | R | |
| 14 | REFCLK+ | I | R | R | |
| 15 | GND | R | R | ||
| 16 | PERn0 | O | R | R | |
| 17 | PERp0 | O | R | R | |
| 18 | GND | R | R | ||
| 19 | PETn0 | I | R | R | |
| 20 | PETp0 | I | R | R | |
| 21 | GND | R | R |
Host-side dimensions drawing:
(From: http://www.rego.com.tw/_admin/upload/product/rego_15562428745ngxni.pdf)
It seems trivial to make a dummy CFexpress card and just use a NVMe drive instead. Project for another day?