UART port found on Fire HD6

[powerpoint45]

I found the UART port on the Fire HD6. It's on the JDEBUG pins. Will post more info later. For now here is a demo:

UART connection layout image
Normal Boot Log
Fastboot Boot Log
My infinite adb reboot script

Edit: RX and TX ports found on the fire HD7 5th gen: http://xdaforums.com/amazon-fire/development/bootloader-unlock-ideas-t3289721/post66265656

 

[mai77]

great find !

there should be some interesting stuff being output via UART

 

[notorious.dds]

I realize that I'm necro'ing a 15 month old thread and for that I apologize. However, I've found NOTHING else on the web regarding this topic, hence the necro'ing.

At any rate, I recently bricked my Fire HD 7 (4th Gen) after flashing the 5.2.0 stock recovery zip. It's bricked to the point of having zero signs of life. So, my questions are:

1. Did you ever locate both Tx and Rx pins on the board?
2. If I can successfully communicate with this board via my TTL serial adapter, is there any chance of a successful recovery?

I realize that the effort required to do this is not justified by the current value of the device. However, that is not my concern. I'm simply in it for the challenge.

Thanks!

 

[bibikalka]

I realize that I'm necro'ing a 15 month old thread and for that I apologize. However, I've found NOTHING else on the web regarding this topic, hence the necro'ing.

At any rate, I recently bricked my Fire HD 7 (4th Gen) after flashing the 5.2.0 stock recovery zip. It's bricked to the point of having zero signs of life. So, my questions are:

1. Did you ever locate both Tx and Rx pins on the board?
2. If I can successfully communicate with this board via my TTL serial adapter, is there any chance of a successful recovery?

I realize that the effort required to do this is not justified by the current value of the device. However, that is not my concern. I'm simply in it for the challenge.

Thanks!

If you are still around, please head over here :
http://xdaforums.com/amazon-fire/development/unbrick-fire-7-5th-gen-downgrade-t3388747

The first question is, can you establish any communication with the Fire HD 2014 preloader when it's bricked ??? If you can, that'd be quite exciting !

 

[powerpoint45]

I realize that I'm necro'ing a 15 month old thread and for that I apologize. However, I've found NOTHING else on the web regarding this topic, hence the necro'ing.

At any rate, I recently bricked my Fire HD 7 (4th Gen) after flashing the 5.2.0 stock recovery zip. It's bricked to the point of having zero signs of life. So, my questions are:

1. Did you ever locate both Tx and Rx pins on the board?
2. If I can successfully communicate with this board via my TTL serial adapter, is there any chance of a successful recovery?

I realize that the effort required to do this is not justified by the current value of the device. However, that is not my concern. I'm simply in it for the challenge.

Thanks!

Man I have been trying for hours now. I'm a bit disappointed. I created a whole breakout board setup for what I thought was the uart port. I still have only found the TX. Going to head over to that other thread as well and see if he knows anything about it. It could still be where I am looking but am just missing it...

 

[toasterboy1]

I know this is a really old post, so I might not get a response, but did you ever figure out the pin for RX? Have a HD6 that all I get is the amazon logo at boot. the how to that I have used to unbrick before does not work because this happened after the update to 5.6.0.1. Wondering how to go about communicating through the JDEBUG port. I used gtkterm like I do when configuring cisco equipment. Are there certain setting for the port to communicate properly. Really trying to bypass the read and write block through the usb that seem to happen with the update.

Update- Found half my answer serial and UART are not really the same thing. Looks like I need a USB to UART cable.

 

[notorious.dds]

Personally, I'd recommend you go with this if you're simply trying to unbrick:

https://xdaforums.com/fire-hd/development/video-linux-iso-unbrick-fire-hd6-hd7-t3474999

I'm pretty sure that it will require that you fully brick it first though (i.e. No Amazon logo, or any real signs of life)

However, if you're getting to an Amazon logo, you should be able to boot to recovery, no? If so, you shouldn't even need to use that aforementioned unbrick process.

I know this is a really old post, so I might not get a response, but did you ever figure out the pin for RX? Have a HD6 that all I get is the amazon logo at boot. the how to that I have used to unbrick before does not work because this happened after the update to 5.6.0.1. Wondering how to go about communicating through the JDEBUG port. I used gtkterm like I do when configuring cisco equipment. Are there certain setting for the port to communicate properly. Really trying to bypass the read and write block through the usb that seem to happen with the update.

Update- Found half my answer serial and UART are not really the same thing. Looks like I need a USB to UART cable.

 

[toasterboy1]

Personally, I'd recommend you go with this if you're simply trying to unbrick:

https://xdaforums.com/fire-hd/development/video-linux-iso-unbrick-fire-hd6-hd7-t3474999

I'm pretty sure that it will require that you fully brick it first though (i.e. No Amazon logo, or any real signs of life)

However, if you're getting to an Amazon logo, you should be able to boot to recovery, no? If so, you shouldn't even need to use that aforementioned unbrick process.

That is the previous unbricking method I mentioned. Worked really well in the past but does not work with 5.6.0.1 it blocked the reading and writing so trying to get around that. It started with trying to flash from cm11 to FireOS and the recovery got lost, so no recovery. It has spiraled down from there. Now I cannot even get to the boot loader because I cannot get into adb. I figure it is a lost cause and already have a replacement, so I figure what better time to learn. It is already beyond broken.

 

[notorious.dds]

That is the previous unbricking method I mentioned. Worked really well in the past but does not work with 5.6.0.1 it blocked the reading and writing so trying to get around that. It started with trying to flash from cm11 to FireOS and the recovery got lost, so no recovery. It has spiraled down from there. Now I cannot even get to the boot loader because I cannot get into adb. I figure it is a lost cause and already have a replacement, so I figure what better time to learn. It is already beyond broken.

Just curious... what if you tried a fastboot cable? I know the fastboot cable is not supposed to work with this device, but I wonder if it makes any difference when there's no recovery installed.

Also, my experience with UART hasn't been super positive. It works, but there's a nice learning curve associated. Subsequently, I found it rather easy to destroy a couple of bootloaders.

Hopefully, you learn quicker than I.

 

[toasterboy1]

Just curious... what if you tried a fastboot cable? I know the fastboot cable is not supposed to work with this device, but I wonder if it makes any difference when there's no recovery installed.

Also, my experience with UART hasn't been super positive. It works, but there's a nice learning curve associated. Subsequently, I found it rather easy to destroy a couple of bootloaders.

Hopefully, you learn quicker than I.

Thought about the fastboot cable. I know it is possible to DIY so I might try that or might just buy one when I get around to getting a 1.8v UART USB board, I think that is what is needed. Not in a hurry now as I just bought a lot of 2 HD6s off ebay that where listed for parts and they are both working fine. Already rooted, TWRP, and CM11 on one as that how the one I destroyed was setup. Hopefully I can get the other one on FireOS 5 and build a device tree and try building CM12, unless I am told that would be impossible. This whole thing started because I wanted to get the headphones working in CM11.

Would appreciate any information you could share on UART. I was just going to try the unbrick ISO through the UART port.

 

[notorious.dds]

Would appreciate any information you could share on UART. I was just going to try the unbrick ISO through the UART port.

Most of my experience with the UART port comes from trying to unbrick wireless routers. UART is simply the serial interface that lets you communicate directly with the board. Once you know which pins are which on your board, getting it connected is relatively straight forward.

However, after you get it connected, this is in my experience where things get messy. There are many different environments in which you could find yourself once connected. Depending on the environment, you may or may not be able to get decent help from Google as to how to procede.

In general, what you're doing with UART is writing directly to the board's memory. This allows you to possibly overwrite the bootloader, recovery, etc.

What I can say is that the ISO will likely do you no good via UART. It's possible that you might be able to extract some info from the ISO that you could use in contructing your UART commands.

If done correctly, you could get your device back. If done incorrectly, you might have a true brick.

 

[Software Service]

Need help same situation here

That is the previous unbricking method I mentioned. Worked really well in the past but does not work with 5.6.0.1 it blocked the reading and writing so trying to get around that. It started with trying to flash from cm11 to FireOS and the recovery got lost, so no recovery. It has spiraled down from there. Now I cannot even get to the boot loader because I cannot get into adb. I figure it is a lost cause and already have a replacement, so I figure what better time to learn. It is already beyond broken.

Ive got 2 hd6 device stuck on fire logo no recovery no fast boot even that linux unbrick method not working with new update which not allow you to read and write

 

[Rortiz2]

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