Rockbox Development > New Ports
SanDisk Sansa c200v2, m200v4, clipv1, clipv2, clip+, and fuzev2
daniel_at:
Hello... I was indeed working on that approch - but somehow none of the accessible pins (i have tested) make sense compared to the description in the datasheet... Non of the JTAG pins are connected to any of the pins from that connector...
Tested some of the dbop_d (Display port data) pins - none seem to be connected with the LCD (Bec. the XPC[0] Pin is also a dbop_d Pin...). But some supply pins i measured were okay.
So there are some possibilities
*) I mixed up the pin-numbering (i am dyslexic :) ) (but i tried rotated and mirrored versions of it)
*) This is a multilayer with not-though-all-layers-vias (dont know if that is possible?)
*) Sandisk has a ordered a special Pinout for the chip
*) My DMS is playing tricks on me...
Dont know - maybe someone with an other hardware could give it a try...
Daniel
atomikpunk:
Hi Daniel and everyone,
- yes indeed I tried multiple "delays" between my USB connection and the unbridging of the pads, but it doesn'T seem to change anything...
- the M250 have a single flash chip, but I did probe the pad and it "beeps" on both flash pin 19. This means that both pin 19 are pulled down simultaneously when the pads are shorted
- I tried using fdisk /dev/sda and the message is "unable to read /dev/sda", fdisk -l /dev/sda yields nothing at all, but I didn't try fdisk -s
- Thanks for the hex editor link, I was used to frhed, but I'll give it a try someday :)
But btw, if you want to try looking at XPC[0], you must pull _down_ the pins, not pull up ;) The bootloader is actually called on low XPC[0], and the unsoldered resistor has a pad to both chips write protect and the other connected to ground, so this is definitely a pull down.
And looking at your pictures, you seem to have the good pinout. However, just in case, did you remove a bit of the protective screen before probing the vias? Or used a needle to probe through it? Because the protective green screen is isolant... I also know that it is possible to have partial or hidden vias, but it grows the production cost so most production will try to stay away from that except when absolutely needed...
andva: "EDIT: It looks like he already did that!" He = daniel_at ;)
daniel_at:
Hello...
Pull down? Why do you think so?
--- Code: ---XPC[0]
BOOT LOADER source select input
1: internal ROM
0: external ROM/Flash
--- End code ---
(see also p21)
Or did I miss somewhere a "not"?
> - the M250 have a single flash chip, but I did probe the pad and it "beeps" on both flash pin 19. This means that both pin 19 are pulled down simultaneously when the pads are shorted
Sorry, I dont understand that sentence fully... One flash... both "pin 19" - [edit]err... just understood it... You have a place for a second Chip on your pcb? Okay ... that makes sense [/edit]
Youre idea about the writelock seems to be true - i googled some (other) datasheets for 32Gbit-TSOP48-Flashe-Chips and they all have \WL on pin 19... Dont understand why that leads to a failed boot - maybe an other pin is also connected to that net.
Maybe youll brave enough to try a method noted by JD24 - there someone just shorted all 8 IO-Pins while booting the player (not a SanDisk at all). Usually it should be enough to ground one or two pins, so that the internal bootldr wont get the correct headers. BUT I dont know what the I/O-Drivers of the SoC would think about it :)
> did you remove a bit of the protective screen before probing the vias?
Yep - i did... i have grinded a very sharp needle-probe for my DMS for that things... And i had connections to most of the pins - but with very high-impedance - so no direct (copper) connection.
Daniel
mitchlr:
Atomicpunk,
Did you get a replacement player yet? If not, perhaps a couple of us who lack the ability to work on the project can see what we can do to get one to you.
Kindest regards,
Rob
atomikpunk:
Hi Daniel, Rob and everyone,
Well the unsoldered pads is definitely for a pulldown resistor because one of its pad is tied to ground (I probed it while unplugged and measured its voltage while plugged). But I think you are right, when XPC[0] is high, the cpu is supposed to boot on internal ROM. So there is something we miss in the circuit... ???
Yeah sorry I wasn't clear, there is effectively 2 flash footprints on the PCB, but on the M250 there is only 1 x 2Gb chip soldered.
About my player, thanks everyone's support and particularly for Bagder (in rockbox's name), which came with a very generous replacement offer to me so that I'll be able to get a replacement player very soon. :) [shameless_plug]It's all possible thanks to the generous donators, so as Rob said, if you aren't able to contribute technically with the development, you can all do your part by donating to the project.[/shameless_plug]
But this is also very good news on the "hardware investigation" side because I'll be a little less shy trying things with my bricked player.
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