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32MB Fuze V1, Checksum error
Jennifur:
--- Quote from: soap on August 21, 2010, 12:06:21 PM ---Don't get me wrong, this hack is cool by default.
But may I ask why?
--- End quote ---
I have thought about doing something like this as well. Can't speak for anyone else, but having the extra RAM would be quite useful for buffering and being able to play GBC roms while listening to music like you can do on the Gigabeat S would be quite nice as well.
sss:
I replaced the 32MB chip (4bit) with a chip should be perfectly compatible, the 16MB HYNIX hy57V281620etp-h (16bit, and from a FON 2100). The datasheets say these two chips are pin for pin compatible and the organization is the same as what was replaced (8MB, 16bit M12L64164A from ESMT).
I did this just to test before I bothered ordering a more ideal chip, the MT48LC32M16A2 (64MB, 16bit Micron chip).
I STILL GET THE BAD CHECKSUM ERROR:
This time the SUM value changed to "175534B"
This means the checksum takes into account the ram module. How do I get around this?
saratoga:
--- Quote from: sss on August 24, 2010, 01:17:47 AM ---This means the checksum takes into account the ram module. How do I get around this?
--- End quote ---
The checksum just steps over the file adding the value of each word. It does not take into account the memory size as I recall. More likely its wrong because the memory isn't working the firmware is corrupted as soon as its loaded into RAM.
funman:
--- Quote from: funman on August 21, 2010, 08:20:26 AM ---You'll probably also need to change the SDRAM settings in memory_init.S
The registers are described in the datasheet for the PL172 memory controller and the settings should be provided by the SDRAM chip manufacturer.
good luck :)
--- End quote ---
No chance it will work if you don't modify the memory controller setup
sss:
When I came home today to try fixing the firmware and bootloader part of this, I realized the fuze would definitely not allow me to change its filesystem (with the USB cable in the device appears to do absolutely nothing, but in fact it gets into a crashed state which requires you to hold the onswitch up for 10+ seconds to reset it so it can attempt to boot again the next time).
So I cannot really boot the fuze, and I cannot connect it to my PC.
I guess the only way to do this is to get the bootloader and firmware right and install it on the fuze DIRECTLY BEFORE removing and upgrading the ram! Since nobody is exactly sure about everything that must be changed, there is no practical way of doing this!
Other than the memory model definitions in firmware/target/arm/as3525/memory-init.S (pick one):
--- Code: ---#define MEMORY_MODEL 0x5
--- End code ---
(8MB)
--- Code: ---#define MEMORY_MODEL 0x9
--- End code ---
(16MB)
--- Code: ---#define MEMORY_MODEL 0xD
--- End code ---
(32MB)
--- Code: ---#define MEMORY_MODEL 0x11
--- End code ---
(64MB)
and the "export MEMORYSIZE=XX" variable in both the firmware and bootloader makefiles (generated from the tools/configure script). I am not exactly sure of what must be changed, and I need to be completely sure the first time because if it's done wrong, it's a toasted fuze that needs the old memory chip reattached to see the light of day again. (Do they make 54 pin TSOP sockets so I can swap ram chips without resoldering?)
I have not yet tried the jumper based recovery mode: http://www.rockbox.org/wiki/SansaAMSUnbrick
nor am I sure if it will work or not. I will probably solder a wires and a switch to those two pads so I can try it without worrying about my tweezers slipping and shorting something.
Is anyone else familiar with memory upgrades on rockbocked players? Any other tips or pointers?
(thanks for the helpful input so far, the PL172 datasheet is a bit of a labyrinth to steer through)
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