Gen 5 Davinci UART0 Pinout ?

Special Developer Edition Firmwares and Hacking on Archos 5 IT, 5/7 IMT, 605/705, with Android, ├àngstr├Âm and other Linux
BamBam
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Gen 5 Davinci UART0 Pinout ?

Post by BamBam »

Can anyone confirm if the Davinci UART0 rxd pin is accessible in any way ?

I can say that TXD appears brought out to pin 9 of the smaller docking connector ( i.e. the one which normally takes the usb sync cable ).

The reason I'm asking is that I have managed to get my 605Wifi into "BOOTME" mode ( i.e. the ROM bootloader of the ARM chip - NOT the Archos bootloader ).

If I can find RXD - there is a good chance to re-flash my device to revert to 1.7.13 AND thus use moldy cheeze / AND therefore fix my hard disk by replacing it.

( So far I have not found RXD - but it could be that it is only enabled by the correct cable - so at least tracing it might help ).
Even if someone can confirm that RXD is not brought out from the BGA - that would help.

Anyone have pictures of the bare PCB without the Davinci DM6441 ?
CheBuzz
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Re: Gen 5 Davinci UART0 Pinout ?

Post by CheBuzz »

There were pictures as you described, with the DaVinci chip removed. Somewhere on this forum. I don't have it handy though so you will have to go a-searchin'.
BamBam
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Re: Gen 5 Davinci UART0 Pinout ?

Post by BamBam »

CheBuzz wrote:There were pictures as you described, with the DaVinci chip removed. Somewhere on this forum. I don't have it handy though so you will have to go a-searchin'.
I saw pictures of the Davinci chip removed from the PCB - but haven't as yet seen the pads from under the chip.

The post seemed to suggest the author had saved the chips - but not the PCB.
Will keep looking.
grond
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Re: Gen 5 Davinci UART0 Pinout ?

Post by grond »

BamBam wrote:The reason I'm asking is that I have managed to get my 605Wifi into "BOOTME" mode
What is that and how did you manage to do this?
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Re: Gen 5 Davinci UART0 Pinout ?

Post by BamBam »

grond wrote:
BamBam wrote:The reason I'm asking is that I have managed to get my 605Wifi into "BOOTME" mode
What is that and how did you manage to do this?
BOOTME is the request sent out by the ARM core when attempting to boot over UART0.

Check page 62 of the Datasheet for the DM6441 http://focus.ti.com/lit/ds/symlink/tms320dm6441.pdf , you'll see talk of the BOOTCFG register - specifically BTSEL0/1
For the Gen5 , it looks like BTSEL is '01'

Setting BTSEL to '11' will cause the ARM to enter internal ROM boot mode ( after reset ) rather than booting from NOR flash ( normal Archos Boot ).
BTSEL1 is accessible - there is a missing link - which when shorted will cause the CPU to enter UART boot on reset.

There is code to talk this boot protocol "DM644x_FlashAndBootUtils_1_50.tar.gz"
( Protocol description is contained in the TI document spraai0.pdf )

So - if we can get the Gen 5 to listen to the reply - we should be able to download code and re-flash.
denotsko
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Re: Gen 5 Davinci UART0 Pinout ?

Post by denotsko »

;) I feel smarter by just reading that man.
Sychophantom
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Re: Gen 5 Davinci UART0 Pinout ?

Post by Sychophantom »

It reminds me of the very early days of Xbox hacking and the eeprom keys.
generic_username
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Re: Gen 5 Davinci UART0 Pinout ?

Post by generic_username »

kinda like the way you flash cellphones if i understand correctly. you just need that diagnostic pins/pads for the IC's and then you force it into a bootloader state (sometimes there are special key combinations needed to enter boot mode, sometimes special diagnostic cables that short one pin to another etc). like what you would do when the factory gets it ready for sale/resale, or for an emergency recovery type of boot
nz
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Re: Gen 5 Davinci UART0 Pinout ?

Post by nz »

BamBam wrote:Can anyone confirm if the Davinci UART0 rxd pin is accessible in any way ?

I can say that TXD appears brought out to pin 9 of the smaller docking connector ( i.e. the one which normally takes the usb sync cable ).

The reason I'm asking is that I have managed to get my 605Wifi into "BOOTME" mode ( i.e. the ROM bootloader of the ARM chip - NOT the Archos bootloader ).

If I can find RXD - there is a good chance to re-flash my device to revert to 1.7.13 AND thus use moldy cheeze / AND therefore fix my hard disk by replacing it.

( So far I have not found RXD - but it could be that it is only enabled by the correct cable - so at least tracing it might help ).
Even if someone can confirm that RXD is not brought out from the BGA - that would help.
... before you start tearing your unit apart, i confirm that
L0wt3ch
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Re: Gen 5 Davinci UART0 Pinout ?

Post by L0wt3ch »

Hey nz, since this product line has been abandoned and all, can you help us with a way to downgrade firmware for the 605? There's a lot of Linux enthusiasts on here dying for a chance to try to install an alternative OS. I think this would be a great way to show a little love to us folks in the Linux community who are also proud Archos owners. What do you say? :)
NITRO1250
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Re: Gen 5 Davinci UART0 Pinout ?

Post by NITRO1250 »

I agree!

I was deeply saddened a few weeks ago to find that youtube no longer runs on my 605 wifi. Give a new OS a chance and give us some more life on our pocket toys :D
BamBam
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Re: Gen 5 Davinci UART0 Pinout ?

Post by BamBam »

nz wrote:
BamBam wrote:Can anyone confirm if the Davinci UART0 rxd pin is accessible in any way ?

I can say that TXD appears brought out to pin 9 of the smaller docking connector ( i.e. the one which normally takes the usb sync cable ).

The reason I'm asking is that I have managed to get my 605Wifi into "BOOTME" mode ( i.e. the ROM bootloader of the ARM chip - NOT the Archos bootloader ).

If I can find RXD - there is a good chance to re-flash my device to revert to 1.7.13 AND thus use moldy cheeze / AND therefore fix my hard disk by replacing it.

( So far I have not found RXD - but it could be that it is only enabled by the correct cable - so at least tracing it might help ).
Even if someone can confirm that RXD is not brought out from the BGA - that would help.
... before you start tearing your unit apart, i confirm that
Insteresting - it almost seems as though that pin is grounded - I wonder if it might be grounded via something that can be isolated.
I suppose it'll have to wait until I have a dead motherboard to play with.
nz
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Re: Gen 5 Davinci UART0 Pinout ?

Post by nz »

NITRO1250 wrote:I agree!

I was deeply saddened a few weeks ago to find that youtube no longer runs on my 605 wifi. Give a new OS a chance and give us some more life on our pocket toys :D
did you try http://www.youtube.com/xl ? this one should still work.
L0wt3ch
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Re: Gen 5 Davinci UART0 Pinout ?

Post by L0wt3ch »

nz wrote:
NITRO1250 wrote:I agree!

I was deeply saddened a few weeks ago to find that youtube no longer runs on my 605 wifi. Give a new OS a chance and give us some more life on our pocket toys :D
did you try http://www.youtube.com/xl ? this one should still work.
Is that a "no"? :p

It sure would be cool if Archos could help us open up these discontinued devices. You never know, it might result in some positive press for your company, in places like Slashdot, etc.

Come on, be a pal! :D
generic_username
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Re: Gen 5 Davinci UART0 Pinout ?

Post by generic_username »

my bet is on an unused pin on the usb or the dock side of the connector... alright who wants to start shorting pins and hope it doesnt brick shit? lol
CheBuzz
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Re: Gen 5 Davinci UART0 Pinout ?

Post by CheBuzz »

What do you think shorting pins is going to do for you, besides possibly frying some ICs? If you want to find a UART pin, you need a logic analyzer.
generic_username
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Re: Gen 5 Davinci UART0 Pinout ?

Post by generic_username »

im not necessarily talking about the uart0, im talking about trying to find a way to force the archos into something similar to what they call DM mode or emergency boot on phones (which in the phone world allows you to flash custom firmwares etc)

also for the record, I DO NOT SERIOUSLY RECOMMEND ANYONE SHORT ANYTHING ON THEIR ARCHOS (unless you are fairly certain you know what you are doing)

i just know on some devices they short one of the pins on the cable to another to indicate to the device it is a programming/serial cable (however since there is a second multi pin connector on the dock thats not used by the usb cable, my moneys on that connector)

edit:
http://e2e.ti.com/forums/t/12354.aspx
i dunno if this is the same chip but it looks like on this one (if i understood what i read) the uart0 pin is muxed with other signals (so even with a logic device it may still be a task to identify without tracing)

edit2: although, i guess there are alot(10+) unused possible pins on the std usb cable:
http://pinouts.ru/PortableDevices/archo ... nout.shtml

Device
Pin Number PC USB
Pin Number Description
1 2 USB D+
2 4 via SMD resistor 104
4 3 USB D+
6 1 USB Vcc
11 4 USB GND
BamBam
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Re: Gen 5 Davinci UART0 Pinout ?

Post by BamBam »

Using a very fine drill ( 0.65mm ) I drilled beneath the area where UART0 RXD is supposed to be.

What was beneath was copper and it appeared it was connected to ground.

So - until someone takes hi-res pictures of the pad layouts beneath the Davinci - this is a no go.

I only have one 605 - so if I remove the davinci - I'll not be able to continue - a bit chicken 'n' egg.

It *might* be that the grounded pin could be isolated - either with some very careful drilling - or ideally there is a link or trace which can be easily cut.

Of course - non of this is for the faint of heart. :lol:
denotsko
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Re: Gen 5 Davinci UART0 Pinout ?

Post by denotsko »

Does anyone here work in medical or dental areas? If I had a 605 I'd take some x-ray images for you at work. Surely 6 or 8 close in x-ray exposures from various angles would help see more PCB details.
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Re: Gen 5 Davinci UART0 Pinout ?

Post by grond »

denotsko wrote:Does anyone here work in medical or dental areas? If I had a 605 I'd take some x-ray images for you at work. Surely 6 or 8 close in x-ray exposures from various angles would help see more PCB details.
Hm, this is just from the physics I learned at school (and the far smaller part I still remember) but isn't

xrays + metal = electricity?

I'm not sure whether x-raying an electronic device is such a great idea.
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