I used JTAG on our own hardware (called "Verdin") through a Segger J-Link Pro JTAG adapter.
I was able to scan the following JTAG IDs
(BOOT_MODE1; BOOT_MODE0; TEST_MODE; JTAG_MOD) = 1100
ID = 0x5BA00477
This is expected
(BOOT_MODE1; BOOT_MODE0; TEST_MODE; JTAG_MOD) = 1101
ID = 0x088E401D
The JTAG ID listed in the BSDL file IMX8MMINI-BSDL.bsdl is 0x1CF80553.
Question: Why am I reading this unexpected ID?
I'm aware that my strap pins are not in compliance with the boundary scan requirements, but according to the block diagrams in the reference manual I should still access the boundary scan controller.
Is there an error in the BSDL file, or am I accessing a different JTAG unit due to the wrong strapping? Unfortunately I cannot make my hardware strappings compliant, and on NXP's EVK JTAG is currently not working at all for me.
Regards, Andy
Hi Andy
>I'm aware that my strap pins are not in compliance with the boundary scan requirements, but
>according to the block diagrams in the reference manual I should still access the boundary scan controller.
according to Figure 4-21. System JTAG Controller (SJC) Block Diagram
i.MX 8M Mini Applications Processor Reference Manual
JTAG_MOD=0 does not allow to access boundary scan controller.
Best regards
igor
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Hi Igor
I fully agree. With JTAG_MOD=0, I see the JTAG ID = 0x5BA00477 (as expected).
My question is about JTAG_MOD=1.
Section 4.10.1.5 of the Reference manual states
Test mode: JTAG_MOD == 1, SJC is the only TAP controller in the daisy chain.
1149.1-compliant, and support 1149.6 AC coupled test.
Therefore I would expected to see the JTAG ID which is defined in the BSDL file (0x1CF80553).
Best Regards, Andy
Hi Andy
I asked internally and was adviced, below:
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Have you followed i.MX8M Mini HDG chapter 5.5 to enter boundary scan mode? This is how JTAG ID of DFT_TAP (for IEEE1149.1) could be seen.
HDG : https://www.nxp.com.cn/webapp/sps/download/preDownload.jsp?render=true
Best regards
igor