Author Topic: Twist the same JTAG pinout into fitting almost everything: is it a good idea?  (Read 1165 times)

0 Members and 1 Guest are viewing this topic.

Offline technixTopic starter

  • Super Contributor
  • ***
  • Posts: 3507
  • Country: cn
  • From Shanghai With Love
    • My Untitled Blog
I found myself getting a bit of habit here: I am using the same pinout, a modified ARM CoreDebug 1.27mm 2x5 connector, for almost all chips that uses JTAG, regardless of what it might be. I have even designed adapters for various debug pods to make them fit the ARM CoreDebug paradigm. Is that a good design habit, or should I shake it ASAP?

Here is the pinout I am using:
VDD
1
2
JTAG_TMS/SWD_DIO/C2_DQ/SJTAG_DQ
UART_TX/USB_D-
3
4
JTAG_TCK/SWD_CLK/C2_CK/SBW_TCK
UART_RX/USB_D+
5
6
JTAG_TDO/SWD_SWO/SBW_TDIO
JTAG_nTRST/TI_TEST
7
8
JTAG_TDI
GND
9
10
SYS_nRESET
 

Offline SiliconWizard

  • Super Contributor
  • ***
  • Posts: 14297
  • Country: fr
Why not.

Just one thing that comes to mind is your use of pins 3, 5, 7. In the pin-out description I have, those are connected to GND. Problem with using kind of a "standard" connector is that there's a probability someone would plug a generic debug probe that shorts those pins to GND (I happen to have one for instance) and you'd thus have them shorted on your board, which may be a problem depending on what's connected to those on some of your boards. Just a thought.

 

Offline ataradov

  • Super Contributor
  • ***
  • Posts: 11228
  • Country: us
    • Personal site
I use the same connector for all programming interfaces, but I just use a standard pinout for the target whenever possible.
Alex
 

Offline technixTopic starter

  • Super Contributor
  • ***
  • Posts: 3507
  • Country: cn
  • From Shanghai With Love
    • My Untitled Blog
Why not.

Just one thing that comes to mind is your use of pins 3, 5, 7. In the pin-out description I have, those are connected to GND. Problem with using kind of a "standard" connector is that there's a probability someone would plug a generic debug probe that shorts those pins to GND (I happen to have one for instance) and you'd thus have them shorted on your board, which may be a problem depending on what's connected to those on some of your boards. Just a thought.
On standard ARM CoreSight connector pins 3 and 5 are GND, and pin 7 is key/NC. Here on my version the debug UART/USB port is grounded but the nTRST is left floating.

I use the same connector for all programming interfaces, but I just use a standard pinout for the target whenever possible.
Hmm... This might be a better idea than mine...
 

Offline ataradov

  • Super Contributor
  • ***
  • Posts: 11228
  • Country: us
    • Personal site
I also made universal 1:1 adapter boards for 10 and 20 pins. Obviously they can be populated with any size connector, since they are 1:1. And gender and positioning (top/bottom) of the connectors can be arbitrary as well.

Here is a picture of a real-life use on a current project. One is a standard Cortex Debug header, the other one is a standard Altera JTAG header.
Alex
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf