Forum : ARM
Original Post
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January 7, 2008 - 11:17am
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Hi, I have a RLink pro, and I want debug my own PCB with this Rlink but I don't find schematic of Rlink. Thanks |
Hi,
You don't need the schematic of the RLink for that.
You just need to use the JTAG-ARM ADP that you received with the RLink. It provides the standard 20-pins ARM JTAG connector as defined by ARM. Here is its description:
signal | 20pts(ARM) | GND | 4,6,8,10,12,14,16,18,20 VCC | 1,2 TRST | 3 TDI | 5 TMS | 7 TCK | 9 RTCK | 11 TDO | 13 RST | 15 DBGRQ | 17 !!! DO NOT CONNECT !!! DBGACK | 19You can find more information in the ARM and ST documentations.
Finally, please note that RST and TRST are two completely different signals and should NOT be connected to each other. It is a common mistake to do so, because they have very similar names. But if you do, then the JTAG communication will very probably fail.
Best Regards,
Vincent
It ok!
Thanks.
can you give us the pinout of the 24 pin cable from RLINK ?
so we dont have to use the 24-20 adapter ?
I also like to know if there exist a "standard" pinout for Jtag STM32 using a 10 pin IDC connector ?
we dont need the RTCK and DBGRQ and DBGACK
so that is 6 signals plus gnd and VCC left, so a 10 pin connector will be fine, I assume.
if we make the 10 pin flat cable like this:
signal
gnd
signal
gnd
signal
vcc
signal
vcc
signal
signal
the last signal will not the perfectly shilded and will have cross talk at hi frequencyes,
so we have to simply put the most uncritical signal there, I think the two reset signals
will contain the lowest rise time.
Hi,
Here it is:
signal | 20pts(ARM) | 24 pts(RLink3) | 14pts (uPSD) / signal ID | | | GND | 4,6,8,10,12,14,16,18,20 | 3,4,10,17,19,21,22 | 3,10 VCC | 1,2 | 1 | 7 TRST | 3 | 6 | 2 TDI | 5 | 8 | 5 TMS | 7 | 12 | 9 TCK | 9 | 13 | 11 RTCK | 11 | 5 | 1 TDO | 13 | 15 | 13 RST | 15 | 11 | 8 DBGRQ | 17 | 9 | 6 !!! DO NOT CONNECT !!! DBGACK | 19 | 16 | 14The signals of the 24-pins connector that are not referenced here must be left floating. They contain other functions (not for JTAG) which might cause electrical damage if used in the wrong way. (12V charge pump, 12MHz clock, etc.) This is why we prefer customers to use our adapters.
As to the shielding, the most important is to make cables short enough. I have connected some of these devices with just a handful of wires without any shielding consideration and it was fine. Only the wires were never longer than 20cm.
Thomas, your suggestion for the 10-pins connector should be fine, but I think that there are already some 10-pins connectors defined by ARM. (or maybe ST...)
Vincent
Thanks !
I have found some info about JTAG and 10 pin IDC here:
http://www.hardwarebook.info/JTAG
but I think I need both JNTRST and NRST for STM32 ?
Hi,
Yes, you do need both TRST and RST. (with or without Ns or Js depending on the guy who wrote the spec)
The connectors described in the page you reference are more like "standard JTAG". I think I saw somewhere a Cortex-specific 10-pins connector, but I cannot find it now... ;(
Vincent
please see this schematic:
I have modified it slightly for STM32, I think if you say this will work
I will make this our in-house standard :-)