LinuxQuestions.org
Support LQ: Use code LQ3 and save $3 on Domain Registration
Go Back   LinuxQuestions.org > Forums > Linux Forums > Linux - Newbie
User Name
Password
Linux - Newbie This Linux forum is for members that are new to Linux.
Just starting out and have a question? If it is not in the man pages or the how-to's this is the place!

Notices


Reply
  Search this Thread
Old 07-30-2013, 02:06 PM   #1
david_8274
Member
 
Registered: Jun 2013
Location: California
Distribution: Ubuntu, Fedora
Posts: 74

Rep: Reputation: Disabled
programming a chip through JTAG vs UART


Hi,

This may be a bit off-topic.
As I know we can load new firmware image to a chip through JTAG or UART. I know that JTAG programming is raw access of the chip's memory thus it doesn't require any pre-existing code(such as a bootloader) in the chip.
My question is, for UART programming, do we require to and pre-existing code (bootloader) in the chip?

Regards,
Dave Xu
 
Old 07-30-2013, 03:08 PM   #2
brianL
LQ 5k Club
 
Registered: Jan 2006
Location: Oldham, Lancs, England
Distribution: Slackware & Slackware64 14.1
Posts: 7,453
Blog Entries: 55

Rep: Reputation: Disabled
Can't help with the question, but press the Report button and ask for this thread to be moved to the Linux - Embedded & Single-board computer forum. You'll hopefully get more attention there.
 
Old 07-30-2013, 03:26 PM   #3
salasi
Senior Member
 
Registered: Jul 2007
Location: Directly above centre of the earth, UK
Distribution: SuSE, plus some hopping
Posts: 4,052

Rep: Reputation: 881Reputation: 881Reputation: 881Reputation: 881Reputation: 881Reputation: 881Reputation: 881
Quote:
Originally Posted by david_8274 View Post
This may be a bit off-topic.
Well, you define the topic, more or less...



Quote:
Originally Posted by david_8274 View Post
As I know we can load new firmware image to a chip through JTAG or UART. I know that JTAG programming is raw access of the chip's memory thus it doesn't require any pre-existing code(such as a bootloader) in the chip.

Up to a point. You don't have to write it, but somebody does. And you may call it 'firmware', if that helps, in any way.

Quote:
Originally Posted by david_8274 View Post
My question is, for UART programming, do we require to and pre-existing code (bootloader) in the chip?
The simple answer is yes. Firstly, something has to put the UART into an appropriate mode. I don't what it is about UARTs, but the defaults are rarely useful for anything, but otherwise you might, conceivably, get away without doing this (but, you'd probably not like the default, so that might not be a biggie).

Secondly, even with the UART in the right mode, something has to take data coming in and interpret it, in some way (was that a command? what command? which is the data, which is the address, etc). That isn't going to happen without some code. Occasionally, you might get some code pre-programmed into the chip, but, again, someone has to do it, even if it isn't you.

If this stuff did happen by default, there would be security implications of there being a universal backdoor which could be used to put bytes into memory (not saying that there aren't other backdoors in some cases or that there aren't some applications where this issue might be unimportant, just that it would be A Bad Thing (TM) if that was true of everything and everywhere).
 
  


Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off



Similar Threads
Thread Thread Starter Forum Replies Last Post
Where does uart console get its value of uart port membase? unifoxz Linux - Kernel 1 12-20-2011 03:28 PM
Why use JTAG Emulator? kennyfly899 General 5 11-16-2009 04:58 AM
Difference between ICE and JTAG? nesta Programming 2 05-07-2007 12:04 PM
Jtag Cottsay Linux - Hardware 2 03-01-2006 07:44 PM
how do I read a camera chip thru an internal usb chip reader? CPUFreak91 Linux - Newbie 2 07-20-2005 01:15 AM


All times are GMT -5. The time now is 06:46 PM.

Main Menu
Advertisement
My LQ
Write for LQ
LinuxQuestions.org is looking for people interested in writing Editorials, Articles, Reviews, and more. If you'd like to contribute content, let us know.
Main Menu
Syndicate
RSS1  Latest Threads
RSS1  LQ News
Twitter: @linuxquestions
Facebook: linuxquestions Google+: linuxquestions
Open Source Consulting | Domain Registration