Add OCP-TAP's TimeHAT V1

[geerlingguy]

Today I received a couple early prototypes of the TimeHAT V1 (not to be confused with TimeHat), which places a PTP-capable Intel i225 NIC on a Pi HAT with PPS in/out (though there aren't full docs as this is an early prototype with a few bodges to get it somewhat functional).

The design files are available here in the Time-Appliance-Project incubation folder, and right now the main issue is Intel's i225 drivers seem to not work on Pi 5 (see #606), whereas they did work on Pi CM4... weird.

[geerlingguy]

I also received the cutest little PCIe card (that's not a PCIe card) along with this TimeHAT V1 prototype:

It's called the 'Time Stick', and it has an ASIX AX88179B Gigabit NIC with PTP (IEEE 1588v2 and 802.1AS). It also has a female SMA for the 1PPS signal from the AX88179B. Linux drivers are located here, and Ahmad Byagowi has a LinkedIn Post with more info:

The offset error is under +/-10ns (1st sigma) because we used Epson's TCXO TGSO32CGN on the left side Time Stick (acting as the the time server). On the Time Stick, in addition to the XO, there are footprints for TCXO and OCXO, should you choose to have a higher stability in your offset correction.

[geerlingguy]

It's on the site here: https://pipci.jeffgeerling.com/hats/ocp-tap-timehat.html

[geerlingguy]

Note: There's a V2, which I'm documenting here: #674

It has fixed a few hardware bugs in V1, so I'll close out this issue and move on to there.