I.MX8MM JTAG daisy chain

[michalkotyla]

Hi,

I see in I.MX8M Mini is two SJC modes:

- JTAG_MOD == 0: DAP is the only TAP in the daisy chain,

- JTAG_MOD == 1: SJC is the only TAP in the daisy chain.

I get it from chapter "4.11.1.5 JTAG topology" of document "i.MX 8M Mini Applications Processor Reference Manual, Rev. 3, 11/2020". There also is a little different (or I do not understand it correctly) information in "Figure 4-23" and "Table 4-29": In MOD 1 only one available TAP is SJC (without DAP's), and in MOD 0 there is everything - SJC, SDMA, DAP's. Also, I found a note in the reference manual (and suggestions on a similar topic on this forum) that I need this IO configuration for daisy chain mode:

"(TEST_MODE, BOOT_MODE1,BOOT_MODE0, JTAG_MOD) = (1110)"

How it should work? which version of JTAG_MOD description is correct and what else I need? Any of these can give me access to DAP and SJC in one session (this is my goal)?

Best regards,

Michał

[igorpadykov]

Hi Michał 

>How it should work? which version of JTAG_MOD description is correct and what else I need?

according to Table 4-29 JTAG_MOD = 0 is used for software debugging.

For bsdl tests it is necessary to follow "NOTE":

IEEE1149.1 standard features are enabled by below IO
configurations: (TEST_MODE, BOOT_MODE1,
BOOT_MODE0, JTAG_MOD) = (1110)

BSLD is described in sect.5. Using BSDL for board-level testing  i.MX 8M Mini Hardware Developer’s Guide

Best regards
igor