JTAG hardware

[ezanen9]

Posted on September 14, 2005 at 12:57

JTAG hardware

[ezanen9]

Posted on September 13, 2005 at 13:40

Hello,

I want to implement the JTAG hardware on my PCB as descibed in the ''hardware getting started.pdf'' (figure 11)from the ST microelectronics site.

Before I implement the JTAG this way, is there somebody who already did this before? And does it work properly this way?

I am doubting because in the schematics of my evaluation board there are extra resistors being added.(see red arrows in attached drawing) These are mainly series/damping resistors.

Will the basic ST microelectronics version work properly?

Thanks,

Jimmey

[ This message was edited by: Jimmey on 13-09-2005 17:11 ]

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Attachments :

JTAG.JPG : https://st--c.eu10.content.force.com/sfc/dist/version/download/?oid=00Db0000000YtG6&ids=0680X000006HtJd&d=%2Fa%2F0X0000000aLV%2FcWM2xLkSjQOGHexAN5u6X0LKPh2vityw6rALyrk3K58&asPdf=false

[halim]

Posted on September 14, 2005 at 06:44

Hello Jimmey,

I used the interface JTAG with the STR710 but I noticed that there is modifications has to do by report has the one indicates in the getting started hardware.

You find in attached file the JATG parts reference (its work very well)

Concerning the addition resistor in your board, all are ok but I suggest to remove R57 or to replace with 0 ohm

Thanks,

Punto

[ This message was edited by: Punto on 14-09-2005 10:15 ]

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Attachments :

JTAG.pdf : https://st--c.eu10.content.force.com/sfc/dist/version/download/?oid=00Db0000000YtG6&ids=0680X000006HtJn&d=%2Fa%2F0X0000000aLY%2FBAzX85KFld09KtXvKZtPQGwBCtM5i5mbKqgHwd5FG.s&asPdf=false

[boris239955]

Posted on September 14, 2005 at 06:53

Hi Jimmey,

I have implemented the basic circuit on a board (except the reset circuitry which is a bit different) and it works fine. I had to reduce the JTAG speed a little but maybe it's due to the length of cable I use.

Note that two of the added resistors in the schematic are 0 ohm, so they don't matter.

According to the doc, the resistor on JTCK can be either pull-up or pull-down.

I don't know about the 100 ohm resistor on JTDO. It's probably used for damping, as you said, but it doesn't seem to be really needed.