topic Re: T4240 couldn't be programmed by JTAG in T-Series

T4240 couldn't be programmed by JTAG

zhangkun2015 — Mon, 19 Dec 2016 03:57:51 GMT

Hello,

We made a board with reference of T4240RDB, recently we met a problem which is shown in the title. After many checks,

we found an abnormal phenomenon:

the impedance between VDD_OVDD_P1V8 and GND is only 9.2 Ohm,while the impedance between P1V8_AVDD and GND is 2262Ohm.
Is there something wrong with the inner part of T4240?

Re: T4240 couldn't be programmed by JTAG

ufedor — Mon, 19 Dec 2016 05:37:43 GMT

Please provide the processor connection schematics as PDF.

Re: T4240 couldn't be programmed by JTAG

zhangkun2015 — Mon, 19 Dec 2016 08:56:05 GMT

Hi,thank you for your reply.

I am a fresher here. How Can I upload the PDF file ?

Re: T4240 couldn't be programmed by JTAG

ufedor — Mon, 19 Dec 2016 08:59:38 GMT

Just attach it to response.

Re: T4240 couldn't be programmed by JTAG

zhangkun2015 — Mon, 19 Dec 2016 09:25:29 GMT

Oh, thank you for your remind.

I choose the pages of the processor connections from the schematic,and made them to PDF files.

Re: T4240 couldn't be programmed by JTAG

ufedor — Mon, 19 Dec 2016 09:36:31 GMT

Now please describe the processor behaviour and restate the question.

Re: T4240 couldn't be programmed by JTAG

zhangkun2015 — Tue, 20 Dec 2016 01:52:08 GMT

OK,Let me state the problem from the beginning.

Actually, last week, my board had just been ready for the frist time programme. But the first time we connected the debug device to the board, the problem happened. The figure is shown below.

OK, the Chinese characters could be ignored. So, we began to check the relevant hardware.

Finally,we found two abnormal states.

the impedance between VDD_OVDD_P1V8 and GND is only 9.2 Ohm,while the impedance between P1V8_AVDD and GND is 2262Ohm. the net of VDD_OVDD_P1V8 is only connected to two places,one is in PDF 24 and the other is in PDF 36

Re: T4240 couldn't be programmed by JTAG

zhangkun2015 — Tue, 20 Dec 2016 01:53:57 GMT

OK, the PDF is attached here.

Re: T4240 couldn't be programmed by JTAG

zhangkun2015 — Tue, 20 Dec 2016 02:12:47 GMT

And the second abnormal state is :

The 1st foot of JTAG connector is short circuit.

and the net of the 1st foot, named "COP_TDO" is directly connected to T4240's pin,which is K42.

Now, we are so worried that there is something wrong with the inside of the T4240.

Re: T4240 couldn't be programmed by JTAG

zhangkun2015 — Wed, 21 Dec 2016 00:54:38 GMT

ufedor‌

Hi,I need your help.Thanks a lot.

Re: T4240 couldn't be programmed by JTAG

ufedor — Thu, 22 Dec 2016 16:38:37 GMT

Please confirm whether the processor is capable to complete its POR sequence - refer to the T4240 RM, 4.6.1 Power-on reset sequence.

Re: T4240 couldn't be programmed by JTAG

zhangkun2015 — Fri, 23 Dec 2016 01:20:56 GMT

Thank you for your reply. But Why the impedance between VDD_OVDD_P1V8 and GND is so low？

Re: T4240 couldn't be programmed by JTAG

ufedor — Fri, 23 Dec 2016 05:13:10 GMT

The impedance in question is not characterized, so it is not specified what is its normal value.