Rockbox Development > New Ports
Cowon D2
torne:
--- Quote from: cowonoid on August 12, 2010, 11:12:27 AM ---wouldn't it be more effective to find out about the exact shematic? Look for some defect D2s or buy one (everyone interested spents a few $) or even use the own one cautiously and disassemble it (like the guys from anythingbutipod)? Measure each pin of a chip with an ohmeter and look where it is connected to and during that tipping the information into Eagle layout designer?
--- End quote ---
Not really, for several reasons:
1) Not every component in a given player has a public datasheet, or can even be identified at all. It doesn't help to know how something is connected if you don't know what it *is*.
2) Most connections are obvious and boring (e.g. buses), there's no need to figure most things out this way at all.
3) Testing with an ohmmeter doesn't actually guarantee there's a plain trace between two things.
4) You have to basically destroy the player to be able to get anything like a full picture, since there's no other way to get to the contacts of a BGA package :)
5) It's really time-consuming and tedious. It's not at all guaranteed to be faster than disassembling the firmware...
Occasionally it's useful to know how certain things are connected (e.g. GPIOs that have no obvious function) and someone will investigate the hardware, but generally a schematic would add little value, and it's really not as easy to produce one as you suggest.
saratoga:
--- Quote from: cowonoid on August 12, 2010, 11:12:27 AM ---I am curious: there were so many hours and days of work spent on backwards-engineering the D2 by disassembling the firmware;
wouldn't it be more effective to find out about the exact shematic? Look for some defect D2s or buy one (everyone interested spents a few $) or even use the own one cautiously and disassemble it (like the guys from anythingbutipod)? Measure each pin of a chip with an ohmeter and look where it is connected to and during that tipping the information into Eagle layout designer?
--- End quote ---
About 99% of the interesting stuff is all on the main system on a chip, so the traces wouldn't tell you much.
cowonoid:
--- Quote from: torne on August 12, 2010, 11:34:37 AM ---1) Not every component in a given player has a public datasheet, or can even be identified at all. It doesn't help to know how something is connected if you don't know what it *is*.
--- End quote ---
For sure. However, every part of the D2 seems to be identified and there was a time at which even the TCC7801 datasheet was available to the public (and for some people it probably still is)
--- Quote from: torne on August 12, 2010, 11:34:37 AM ---3) Testing with an ohmmeter doesn't actually guarantee there's a plain trace between two things.
--- End quote ---
Then an oscilloscope and applied AC to the contacts. There surely is a way to check on physical connection.
--- Quote from: torne on August 12, 2010, 11:34:37 AM ---4) You have to basically destroy the player to be able to get anything like a full picture, since there's no other way to get to the contacts of a BGA package :)
--- End quote ---
If I have the datasheet and thus the PIN descriptions and locations; couldn't I guess the traces? (the traces must leave the chip somewhere)
--- Quote from: torne on August 12, 2010, 11:34:37 AM ---5) It's really time-consuming and tedious. It's not at all guaranteed to be faster than disassembling the firmware...
Occasionally it's useful to know how certain things are connected (e.g. GPIOs that have no obvious function) and someone will investigate the hardware, but generally a schematic would add little value, and it's really not as easy to produce one as you suggest.
--- End quote ---
Probably it would be much work, but with a different result than disassembling the firmware: you would know the whole architecture and could build up your own rockbox low-level firmware, which has nothing todo with the original one.
--- Quote from: saratoga on August 12, 2010, 11:40:36 AM ---About 99% of the interesting stuff is all on the main system on a chip, so the traces wouldn't tell you much.
--- End quote ---
You mean, it's in the software for the TCC processor? With rockbox all the original soundprocessing software is screwed up anyway, isn't it?
What I mean is: there are people in this forum speaking about building an own DAP dedicated for rockbox (which is amazing!)
What would be the difference between this player and the D2? Isn't it, that you know every connection and the intention of every single part?
saratoga:
--- Quote from: cowonoid on August 12, 2010, 02:04:54 PM ---You mean, it's in the software for the TCC processor?
--- End quote ---
Hardware and software. What I'm saying is theres very little of the player on the board. Most of it is inside a single chip. Finding traces doesn't help if nothing of importance uses traces.
--- Quote from: cowonoid on August 12, 2010, 02:04:54 PM ---What I mean is: there are people in this forum speaking about building an own DAP dedicated for rockbox (which is amazing!)
What would be the difference between this player and the D2? Isn't it, that you know every connection and the intention of every single part?
--- End quote ---
You pick parts that are all well documented, and then you don't bother with ones that would require reverse engineering software (like the D2's flash translation layer).
peaceful1:
guys in the last few weeks I cant use new rockbox builts, mostly they don't boot any more, can anyone give me a clue what to do ?!
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version