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?
Hi,
Great work! I found your page when I searching CFexpress Type A Pin assignment.
Still not found any usefull info…
But I assume that the CFe-A Pinout is almost same as Type B from Pin9 to Pin21, not sure.
Do you have some info for this Type A card?
Hytean,
Looking at a picture of a CFExpress Type A card at https://www.nextorage.net/en/articles/pr002/ – and assuming that longer pins are power with the intent that power/GND are made before others on insert, and broken after others on removal, I think you are correct that it’s the same as Pin9 to Pin21, with Pin9 on the left of the picture in that link
Thank you a lot for this post!
I have one question:
Do I need to pull pin 4 (GND Lane 1) to ground on a host device which has only a single lane (Raspberry Pi CM4 in this case) or do I have to leave it floating?
Best regards,
Richard