Swan Project
From S1MP3 Wiki
The Swan firmware project aims to provide a complete operating system replacement for Actions based MP3 players (aka "S1MP3" or "MP4" players), especially the most common ATJ2085 types. This includes both a kernel and all shell (GUI) applications as well as a software development kit.
The goals of the project are described in detail at Swan proposal.
This is a preliminary specification for our own open source firmware for S1MP3-type players.
Use the talk page to propose your ideas or correction or to simply ask questions.
The goal is to make it at least just as powerfull as the stock firmwares, but easier to develop on.
SWAN is split in three parts: the Kernel, the API libraries and the applications.
Contents |
Wish List
Stuff we would like to see on swan : Swan Wish List
Resources we have
The ATJ2085 has the following resources:
- BROM/TROM. We don't touch those for now, but just leave the current rescue image in place.
- ZRAM This is 16KB of non-banked memory
- IPM/IDM. This is 6*16+4K=100K of memory, mapped to a 16K space. This is shared with the DSP, in such a fashion that the DSP programs and data occupy a slice of memory in all the banks. What's left would be something like 10K*6+4K.
- NOR flash. Lots of it :) It's probably quite slow to load something from it, though, with all the ECC checking going on.
About memory
Most of the ZRAM will be used for the OS-routines and display drivers, etc, and the rest of it as a data area to keep variables which shoudl remain persistent between bank-switches. If the Zram isn't enough, we can probably use a few bytes of IPM/IDM-banks for the slower routines, and we can load the really not much used routines (USB etc) from the NOR flash if needed. We can then use another slice of IPM bank to fit the currently running application in, and a third one for the background tasks like playing mp3s while another app is running, which can be used by the app but which would mean no concurrent mp3s.
Kernel
This is the part that does things like load programs from flash and execute them, schedule programs, act like a hardware abstractor. It has drivers for devices that aren't exactly the same across players, like the display, keyboard, FM-radio, flash...
The OS will be a single-tasking OS, there's not enough RAM to do more than just the tiniest bit of multitasking. The Z80 core isn't designed for it, either. The ideas the original firmware already uses will be used here too: an OS in RAM to handle the filesystem, display etc, a background driver to play music files and do other stuff in parallel with the currently running app, and the currently running app itself.
Libraries
Click here to read the full API specification
The API is a set of functions which allow the Applications Programmer to Interface to the hardware without the need to understand how the hardware works.
Applications
The base applications which use the API libraries for useful purposes, e.g. edit playlists, play a game, record sounds, ... We already have a few of them, see Main Page
Current Status
Toolchain
Nothing has been decided yet. Some candidates are Z88dk and sdcc. Z88dk seems to be used by the most project members.
Kernel
Contributors: Kidscracker, Bluechip
Kernel's first draft is in progress, see it!
Also see Swan.
API
Contributors: Bluechip
The API specification is complete, see API.
User Interface
Contributors: Wladston, Ian Hawdon, Abner
We have a set of user interface mockups, see User interface.
Software Development Kit
We have S1SDK, but it needs to be made compilant with the [[API].
