The interface is based on the WCH CH376 chip and allows access to USB mass storage and other USB devices on CPC.
The CH376 chip implements FAT32 in hardware, which means no filesystem driver is needed on the CPC side. This makes it very easy to use the interface with a microSD card, USB stick or hard drive and access files on the FAT32 partition directly, without using a lot of CPU power or memory on the CPC.
It also implements the lower level aspects of USB, making it relatively easy to write drivers for other USB devices (mouse, joystick, ...). It is simple enough that the mouse driver was initially written completely in BASIC.
This will allow to, for example, use one board for mass storage, and the other to connect various USB devices: mouse, MIDI controller, printer, whatever you need (as long as you find someone to write a driver).
Strictly speaking, it might be possible to handle both a mouse and a USB stick on one card by using a USB hub. But this has to be coded and tested, the CH376 documentation is unclear on this topic. [https://www.cpcwiki.eu/forum/amstrad-cpc-hardware/albireo-usbsd-interface-for-cpc-new-version-without-serial/msg248489/#msg248489 Source]
[[File:Albireo 2.0 top.jpg|500px]] [[File:Albireo 2.0 bottom.jpg|500px]]
The decoding is clean, this means there aren't any mirror ports or undecoded address bits. Just the addresses listed below are used.
The addresses are in the I/O range, which means you access them with the OUT and IN instructions. They are not memory mapped, and to match with the CPC address decoding, the address is decoded on 16 bytes. This makes using OTIR and similar looped instructions tricky, but is required for compatibility with the CPC.
==== CH376 registers ====
== Links ==
*[https://www.cpcwiki.eu/forum/amstrad-cpc-hardware/albireo-usbsdserial-interface-for-cpc/ Albireo] [https://www.cpcwiki.eu/forum/amstrad-cpc-hardware/albireo-usbsd-interface-for-cpc-new-version-without-serial/ Albireo 2.0] Topics on CPCWiki forum
*[[Media:Albireo1.0 schematics.pdf|Albireo KiCad schematics]]
*[https://framagit.org/shinra/albireo Albireo project] [https://framagit.org/offset/albireo-acepansion Albireo ACEpansion] on Framagit
*[https://pulkomandy.github.io/shinra.github.io/albireo.html Albireo - Programmer's manual]
*[[Media:Ch376ds1.pdf|CH376 datasheet]] [[Media:CH376DS2.PDF|CH376 auxiliary commands]] USB flash drive and SD card controller