Re-sent cos this PC defaults to Rich Text. Sorry Admins.
From: keithjamieson@hotmail.co.uk To: main@lists.alug.org.uk Subject: RE: [ALUG] JTAG Date: Thu, 28 Apr 2011 18:05:28 +0100
Mark
JTAG is used to use a PC to program an embedded device. I have made one the parallel port of a PC to recover my Linksys WRT54G. It also, I think, can be used to debug the device.
Its a "standard" which is adopted by manufactured, althought I have not heard of the newer one you mentioned. But I have not been in this field for some time!
In the older times you would remove an EEPROM and pur it into a programmer, then put it back into your device. This is the lead to illiminate that need.
Keith
On 28/04/11 18:07, keithjamieson@hotmail.co.uk wrote:
JTAG is used to use a PC to program an embedded device. I have made one the parallel port of a PC to recover my Linksys WRT54G. It also, I think, can be used to debug the device.
Its a "standard" which is adopted by manufactured, althought I have not heard of the newer one you mentioned. But I have not been in this field for some time!
So is JTAG "standard" in that if I need a JTAG programming lead then any will do? When I look around a lot of them seem to refer to ARM or whatever, suggesting that the cable is specific to a certain chipset. I ordered a cheap USB JTAG cable off eBay to play with but I'm not sure whether I need to be a bit more careful about picking the right kit for the right job.
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Date: Tue, 3 May 2011 14:07:47 +0100 From: mark@more-solutions.co.uk To: main@lists.alug.org.uk Subject: Re: [ALUG] JTAG
On 28/04/11 18:07, keithjamieson@hotmail.co.uk wrote:
JTAG is used to use a PC to program an embedded device. I have made one the parallel port of a PC to recover my Linksys WRT54G. It also, I think, can be used to debug the device.
Its a "standard" which is adopted by manufactured, althought I have not heard of the newer one you mentioned. But I have not been in this field for some time!
So is JTAG "standard" in that if I need a JTAG programming lead then any will do? When I look around a lot of them seem to refer to ARM or whatever, suggesting that the cable is specific to a certain chipset. I ordered a cheap USB JTAG cable off eBay to play with but I'm not sure whether I need to be a bit more careful about picking the right kit for the right job.
The electrical connections are the same, but the pin outs differ. I made the one for the WRT54G, see http://www.tiaowiki.com/w/Debrick_Routers_Using_JTAG_Cable And from http://www.dd-wrt.com/wiki/index.php/JTAG_pinouts I get the info <<<<<<<<<<<<<< Buffalo WBR-G54 jtag is pins 1-12 (normal jtag pinout: 3: TDI, 5: TDO, 7: TMS, 9: TCK)
| |mini-pci card
| |_______________
| 2 12 JP1
| o o o o o o |o o|
| o o o o o o |o o|
| 1 11 JP2>>>>>>>>>>>>>>>>> which appears to be the "standard" connection
2 4 6 8 10 121 3 5 7 9 11
But some do have "other" pin outs, like below have the same things on the same pins but they are numbered differently!! <<<<<<<<<<<<<<Airlink AR430W The router follows the MIPS 2.6 EJTAG Specification and has the same PIN information. But on the board the PINS are layed out as
1 2 3 4 5 6 7
14 13 12 11 10 9 8
1 - nTRST
3 - TDI
5 - TDO
7 - TMS
9 - TCK
2, 4, 6, 8, 10 - GND [you only need one GND for JTAG]
You dont need the following pins
11 - nSRST
14 - VCC
12, 13 - N/C
>>>>>>>>>>>
HTH Keith
On 08/05/11 08:59, keithjamieson@hotmail.co.uk wrote:
The electrical connections are the same, but the pin outs differ. I made the one for the WRT54G, see http://www.tiaowiki.com/w/Debrick_Routers_Using_JTAG_Cable And from http://www.dd-wrt.com/wiki/index.php/JTAG_pinouts I get the info
Hmm, thanks for this. Doesn't look like something I can just dip my toe into!
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Date: Mon, 9 May 2011 10:56:56 +0100 From: mark@quarella.co.uk To: main@lists.alug.org.uk Subject: Re: [ALUG] JTAG
On 08/05/11 08:59, keithjamieson@hotmail.co.uk wrote:
The electrical connections are the same, but the pin outs differ. I made the one for the WRT54G, see http://www.tiaowiki.com/w/Debrick_Routers_Using_JTAG_Cable And from http://www.dd-wrt.com/wiki/index.php/JTAG_pinouts I get the info
Hmm, thanks for this. Doesn't look like something I can just dip my toe into!
Its not *that* bad. Its if you have pin one which is nTRST but its on pin 7. Get a socket which fits your kit and put the leads into it,if its a ribbon cable then split the wires. Then use a plug which goes into the cable then solder the lead from pin 7 from the socket onto pin one on the plug. Repeat for the rest of the wires in use.
Its not rocket science, just a bit *big* if you have not done it before. If you already have a check JTAG coming, then whats the price of a few bits from Maplins?
Have a think before you dismiss the idea. If you do go ahead and make a cable up, then write in permanent ink on the cable what it fits!!! If you get a few its not easy guessing the correct one.
Keith
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keithjamieson＠hotmail.co.uk -
Mark Rogers -
Mark Rogers