Rockbox Development > New Ports
SanDisk Sansa c200v2, m200v4, clipv1, clipv2, clip+, and fuzev2
funman:
--- Quote from: FlynDice on May 04, 2009, 07:55:14 PM ---Do we use the ide interface at all for the ams sansas? I'm trying to understand why the ide interface gets enabled and clocked in sd_init. I thought the internal sd was on the nand interface and the microsd was on the sd/mmc interface, connected to the processor through the apb/ahb bus. Does the ide interface need to be enable for some reason? DRAM? What's the connection here?
--- End quote ---
The IDE interface is needed for internal SD to operate correctly, but I don't know how it is connected internally : probably a Sansa extension.
To verify, just comment out the line which enables IDE clock and see if SD works.
Note : if we reset IDE interface (in CCU_SRC, see system_init()) SD stops working, all other peripherals can be resetted.
FlynDice:
I posted http://www.rockbox.org/tracker/task/10191 to see if synchronous clocking has any advantage. For MAX speed it runs the processor at 248Mhz and peripherals at 248/4= 62 MHz. For NORMAL speed it runs the processor and peripherals at 31 Mhz. I don't know that this is any better than what we do now but I thought it was worth checking out. It seemed to be more stable while I was investigating the mmu but I think funman may have found a solution there. The one thing I can say for sure is better is the wheel light flashes much less during disc accesses, but it still flashes once in a while.
rp:
How is the wheel light connected to this?
I thought it's controlled by GPIO D7?
bertrik:
If we run the processor at less than 200 MHz, the core voltage can be reduced from 1.2V to 1.1V, according to the as3525 datasheet (see the note in paragraph 6.2.2) . This could save some power (in a simple approximation dissipated power is inversely proportional to the *square* of the voltage). I think we don't really *need* to run at absolute maximum speed of 248 MHz, so we could save power by running slightly lower than 200 MHz.
By the way, I noticed that AMS has a new revision (rev1.13) of the as3525 datasheet on their website, see http://www.austriamicrosystems.com/eng/Products/Mobile-Entertainment/High-Performance-Microcontrollers
Llorean:
You really should make the full speed available while boosted, I'd imagine. Otherwise you're potentially cutting off file formats (ApeV2 at certain compression levels possibly) as well as restricting the bitrates and possibly resolutions at which video can be encoded.
The whole point of being boosted is that things that need a large amount of CPU can get the full capabilities of the player behind them.
If there's a role for "not quite full power" it should probably be engineered in as a general thing, rather than choosing to limit just one port (well, set of ports).
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version