5,606,530 Members 33,594 Now Online
XDA Developers Android and Mobile Development Forum

UART Location How-To

Tip us?
 
AdamOutler
Old
#1  
AdamOutler's Avatar
Recognized Developer - OP
Thanks Meter 9432
Posts: 5,126
Join Date: Feb 2011
Location: Louisiana

 
DONATE TO ME
Plug UART Location How-To

As much as I despise Qualcomm's lock down practices, I must admit that the Qualcomm processor is pretty darn solid. There aren't too many problems with Qualcrapp . However, that's now and I've got some information which may help some of you out in the future.

I did some hacking last night on a live stream with a few other XDA members from this and other forums. The goal was to find the UART location on the AT&T Galaxy S3.

Why, you might ask, would this be useful? During kernel and bootloader development, sometimes the device won't boot to the point where you can obtain logs to determine the problem. UART can provide the realtime eyes-on that you need to troubleshoot such problems.

So the process was as follows... On a rooted device, pull the kernel. Extract it. Add command line parameters to enable UART.
Code:
console=ttyHSL0,115200n8 loglevel=9
Recompress into a boot.img. upload with Heimdall. Teardown the device. Adb shell into the device. Execute the following code so you push data through the UART port and know if the device has locked up.
Code:
su
while [ 0 ]; do date| tee /dev/ttyHSL0; busybox sleep .5; done
After that, you can locate the UART port by probing at 115200bps.

The TX from the board (your RX lead] is placed 2nd from the bottom on the battery side of the board. RX is either the one above that or middle on the other side.

Video:


In the video, at about 5 minutes in, I said I didn't know what the 31 value was... and the kmesg logs were pretty thin.. Well, turns out they are the kernel message levels. For full logging, change that to 987654321. Samsung usually uses the 9 identifier to represent shell access .

So, I hope this helps. UART provides eyes before any other method of debugging (aside from JTAG) begins to work. UART is the first thing to do in order to make a device into a development board.
Flash with Odin on Windows, Linux and Mac. Use JOdin3, Available in a web browser or offline
Check out my developer pages. Add me to your circles on Google Plus.
The Following 14 Users Say Thank You to AdamOutler For This Useful Post: [ Click to Expand ]
 
AdamOutler
Old
#2  
AdamOutler's Avatar
Recognized Developer - OP
Thanks Meter 9432
Posts: 5,126
Join Date: Feb 2011
Location: Louisiana

 
DONATE TO ME
Forgot to mention.. There is surely a switch in the PARAMS to enable early bootloader logging. This is yet to be found.
Flash with Odin on Windows, Linux and Mac. Use JOdin3, Available in a web browser or offline
Check out my developer pages. Add me to your circles on Google Plus.
The Following 4 Users Say Thank You to AdamOutler For This Useful Post: [ Click to Expand ]
 
stratatak7
Old
#3  
stratatak7's Avatar
Recognized Contributor / Swappa Representative
Thanks Meter 2463
Posts: 1,540
Join Date: Jun 2011
Location: Blacksburg, VA

 
DONATE TO ME
Thanks Adam, amazingly helpful as usual

 
Plays2
Old
#4  
Senior Member
Thanks Meter 103
Posts: 250
Join Date: Sep 2011
Location: Peachtree City
Wow awesome dude, good work! You never dissappoint haha.

Sent from my SAMSUNG-SGH-I747 using xda premium
-----------------------------------------------------------------------------------
Check me out on Youtube! http://bit.ly/16NAodO
 
upndwn4par
Old
#5  
upndwn4par's Avatar
Recognized Developer
Thanks Meter 8601
Posts: 3,116
Join Date: Jan 2012
Location: Beyond the Wall
I haven't watched the video yet because the loading is soooo slow.

Is it possible to uart in to the headphone jack on this device?

We were able to do this on the Atrix 4G.
 
AdamOutler
Old
#6  
AdamOutler's Avatar
Recognized Developer - OP
Thanks Meter 9432
Posts: 5,126
Join Date: Feb 2011
Location: Louisiana

 
DONATE TO ME
Quote:
Originally Posted by upndwn4par View Post
I haven't watched the video yet because the loading is soooo slow.

Is it possible to uart in to the headphone jack on this device?

We were able to do this on the Atrix 4G.
No. If anything were possible it would be the USB port.
Flash with Odin on Windows, Linux and Mac. Use JOdin3, Available in a web browser or offline
Check out my developer pages. Add me to your circles on Google Plus.
 
jamcar
Old
#7  
jamcar's Avatar
Senior Member
Thanks Meter 370
Posts: 1,166
Join Date: Aug 2010
Location: Virginia Beach
Quote:
Originally Posted by AdamOutler View Post
As much as I despise Qualcomm's lock down practices, I must admit that the Qualcomm processor is pretty darn solid. There aren't too many problems with Qualcrapp .
Wasn't fully aware they had lock down practices. Could you say more about that? Like what is it? What did they do?
Thanks.


Aaron Swartz, Rest in Pixels.

Aaron Swartz, Rest in Pixels.
check me on twitter jamcarXDA
Remember if i helped you then hit "Thanks"
 
m11kkaa
Old
#8  
m11kkaa's Avatar
Recognized Contributor
Thanks Meter 1268
Posts: 797
Join Date: Jan 2011

 
DONATE TO ME
I try to find the UART port on an APQ8064(Mi2 and Nexus4 are using it).
Just one question: how can I probe uart? just random connecting my RX to any pins on the board?
Can't this completely break the hardware?

Follow me on twitter: https://twitter.com/m11kkaa

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes


XDA PORTAL POSTS

Speed up the ROM or Kernel Build Process

Creating a kernel, ROM, or any other development projectrequires knowledge and tools. While … more

Google Glass Now Open to Anyone… with $1500 to Spend (Update: Not Anymore)

Google Glass, which recently received its official update … more

Android 4.4.2 OTA Now Available for the Verizon Droid DNA

A couple of days ago, we talked about how the Android 4.4.2 upgrade for the HTC … more