Rockbox General > Rockbox General Discussion
work on best low cost mp3 player for rockbox
saratoga:
ATJ213XX is pretty old, so it may not be as efficient as newer parts. Still, well optimized most chips do roughly 1.5 to 2x what the vendor claims once properly optimized.
The new atj cores without dram do well by having such simple hardware, but not that well. The old as3525v2 uses nearly the same current once voltage scaling is enabled, and it has real dram and no DSP, just arm9e. I think the DSP is more about cost savings than anything.
hunterleo:
--- Quote from: pamaury on November 03, 2015, 07:24:58 AM ---I would be extremely careful with manufacturer figures. For example the Fuze+ with Freescale OS lasts 25h on a 550mAh battery but Rockbox lasts around 45h. And most of the savings don't come from the CPU, since with proper frequency management you can decrease it a lot, but rather properly shutting down or suspending LCD, touchpad, mmc/sd.
--- End quote ---
Great! Thanks for the advice. I will list all the chips available, and let's figure them out which one is best for rockbox.
hunterleo:
--- Quote from: wodz on November 03, 2015, 11:37:05 AM ---I am working on Iriver e100/150/200/300 series (e150 is my playground). If you have documentation for atj213x (or more precisely the one I don't have) that would be helpful.
--- End quote ---
Could you list the documentation precisely you don't have? I checked with the manufacturer, they have several versions (new and old)of packages of documentation for the chip is quite old.
wodz:
I have lots of various documents BUT the crucial one I have are:
Actions ATJ2135N Product Datasheet version 1.0 dated May 2008
Actions ATJ2135 Product Programming Guide version 1.1 dated January 2007
1) I'd love to have linux sources (which I know exist for atj2137n) and some document describing various members of this family (what is the difference between 2135 and 2137 etc.).
2)USB controller is not documented at all in datasheet. I have some idea how it works (I ported hwstub and it works pretty well) based on reverse engineering but thats it.
3)Flash controller documentation is vague and incomplete in datasheet.
4)DSP core is not documented. I know it is instruction compatible with ADSP-21xx but I suspect it has 24bit data path and have some custom registers.
5)Documentation for eCOS SDK would be nice - what are components:
- what is BREC, MBREC how they are stored on flash
- how exactly boot process is done
- what is actually run on DSP
6)I have no idea what FTL is used.
Any help in this topics is appreciated.
hunterleo:
OK. wodz. I will search them.
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