SWD/Jtag communication failure

[lpcware]

Content originally posted in LPCWare by h.lotfi on Tue Sep 23 02:05:58 MST 2014
Hi,
i Design a board with LPC4357, and i Program it.
after about 30times programing i have a error in programing!!!
Keil unknown my programmer!!
i use ulink2 and keil Version4.72
now when i want program my board ,i get this error:
in jtag mode: Jtag communication failure
in SW mode: SWD communication failure

any body can offer me?

thank you in advance

[lpcware]

Content originally posted in LPCWare by feynman on Wed Feb 10 03:21:16 MST 2016

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Quote: bavarian

One word to the possibility of damaged JTAG pins:  we have seen situations where the voltage potential between the power domains of the board supply and the debugger supply (normally 2 separate switching power supplies) were huge. During physical disconnect/connect events there could be short but rather high current peaks which could destroy JTAG/SWD input pins. Then you need to replace the chip in case you need the JTAG port for your work.

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We seem to have this very issue with our LPC4357 parts and our Keil ULINKpro debuggers. When the problem occurs, the only way to program the device is via flash magic.
We have to replace the LPC4357 to be able to use our Keil debuggers again.

Ist their more information or a workaround to this issue?

[lpcware]

Content originally posted in LPCWare by bavarian on Fri Sep 26 02:40:35 MST 2014
I see the following ways to analyze the situation:

[list]
  [*]  Please enter into ISP mode (LOW level on pin P2_7 during reset). You need to configure the bootmode pins to USART0 or USART3 bootmode. This causes the bootloader to wait for an input on the selected UART.
  [*]  If you then can't see cores in the Keil debugger settings, the debugger connection is broken (one or more of the JTAG pins damaged). Please send with a terminal program a '?' character to the selected UART (115kbaud) and check if the chip responds with a string. If this is the case FlashMagic should also work.
  [*]  If you see the cores, you should try to erase the internal flash and then check if everything is back to normal
[/list]


One word to the possibility of damaged JTAG pins:  we have seen situations where the voltage potential between the power domains of the board supply and the debugger supply (normally 2 separate switching power supplies) were huge. During physical disconnect/connect events there could be short but rather high current peaks which could destroy JTAG/SWD input pins. Then you need to replace the chip in case you need the JTAG port for your work.

Regards,
NXP Support Team

[lpcware]

Content originally posted in LPCWare by h.lotfi on Wed Sep 24 03:38:03 MST 2014

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Quote: LabRat
Boot into ISP...

http://www.lpcware.com/content/faq/lpcxpresso/regaining-debug-access

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Thank you for answer.
flash magic can't connect to my board!

i did this mechanism:
i don't have any mechanism that easily i can erase the chip!
but soldered three pull-down resistors on P1.1,P1.2,P2.8 and a pull-up resistor on P2.9, and P2.7 ,reset pins was pull-uped.
and use this circuit :
http://www.mediafire.com/view/e77118w7sjichg6/program.jpg
i want use USART3 and flash magic tool for erasing the chip!
but flash magic can't connect to my board!!

[lpcware]

Content originally posted in LPCWare by LabRat on Tue Sep 23 02:30:20 MST 2014
Boot into ISP...

http://www.lpcware.com/content/faq/lpcxpresso/regaining-debug-access