Go Back   USB JTAG > General > News

Thread Tools Display Modes
Old 04-18-2010, 11:15 AM
usbbdm usbbdm is offline
Join Date: Jul 2005
Posts: 8,885
Default 24MHz JTAG clock?

Some devices needs faster speed. Like XBOX and big SPI flash.
Just want to ask if there is any interest to double the speed of JTAG clock. I can raise the clock speed for JTAG (SPI) and new code needs to be changed. This will be another version of hardware (different CPLD programming).

Pros. For some device it will significantly improve the speed (XBOX for example or big SPI flash, SB6120).

Cons. The cable must be short or you might get corrupt data. Lower level software needs to be re-written.

For normal MIPS JTAG the speed improvement might not be visible for DMA but should see much faster on non-DMA programming. I think with the current speed EJTAG is enough. What I found is not enough is people who program big NAND on XBOX and any speed improvement is needed.
Reply With Quote
Old 04-21-2010, 11:43 PM
usbbdm usbbdm is offline
Join Date: Jul 2005
Posts: 8,885
Default Prototyping 24M clock.

I made small change to the CPLD of USB JTAG NT and let the default JTAG clock to be 24MHz.
Modified the SPI code on SB6120. Here is the test result.

1. Read jump from 915KB/s to 1321KB/s 44% increase.
2. Write jump from 253KB/s to 273KB/s. 7.3% increase.

The standard length of USB JTAG NT cable seems to be able to handle this speed without error. Since SPI on USB JTAG NT is a bonus so the speed cannot be optimized. If the NT is built only for SPI it can be much faster (I will expect at least 3MB/s or even 6M speed if we use full 48M clock).

You can see the write speed does not change much since the the flash itself needs a lot time to program and the software have to wait.

Here is the screen result screen to program and cmpram the SB6120 firmware.
-flshdct 0 
 Found Address= 00000000 25FL064A
-program 0 800000 
 Erase starts...
 Erase time 00:00:46 (.484)
 Program Starts...
 Program speed 273.08 KB/s
 Program time 00:00:30 (.203)
 Program pass, if no further programming needed, power off/on the target
-cmpram 0 800000 
 Time 00:00:06 (.437) 
 Compare data OK
The read speed displays as 1321.97KB/s.

Translate to MIPS JTAG for DMA JTAG it will not be a lot faster, but for non-DMA or trap on mode the read speed can be improved (expect 30-40% faster at least).

The above is only experimental. If absolute speed is needed I will make a version for it (maybe call NT V2) so people who need speed can get those.
Reply With Quote
Old 04-22-2010, 11:58 AM
CAPONE CAPONE is offline
Senior Member
Join Date: Dec 2008
Posts: 5,093

Great News Buddy
Reply With Quote
Old 04-22-2010, 07:59 PM
lordvader lordvader is offline
Join Date: Mar 2009
Posts: 25

wow..good news and good job admin
Reply With Quote
Old 06-01-2010, 11:21 PM
usbbdm usbbdm is offline
Join Date: Jul 2005
Posts: 8,885

I think I would work on ARM first. The first device I will work on is LPC2103 (ARM7). Hope to get this working soon then find an ARM 9 target to work on. I have a 2Wire modem/router and that should be an ARM core. The protocol for ARM JTAG is different for MIPS, the NT hardware is optimized for MIPS JTAG, so I expect different speed for ARM JTAG.

The 24MHz JTAG can done easily but there is not a lot of interest in it. Most people would like to see more devices being added to the support list.

Another task is to support GDB for MIPS development. There was once a need for GDB support for PIX32MX and the job started and then stopped. I still have the PIC32MX development board. When I have time I might finish this task.
Reply With Quote
Old 07-12-2010, 05:59 PM
jsalz45 jsalz45 is offline
Junior Member
Join Date: Sep 2009
Posts: 5

u have any u want to sell i would take one even if itz a beta
Reply With Quote

Thread Tools
Display Modes

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 On
HTML code is Off
Forum Jump

All times are GMT -7. The time now is 02:42 AM.

Powered by vBulletin® Version 3.7.3
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.