we have i.mx8mplus-EVK and custom board. we tried to detect the custom board using jtag but getting unable to detect the board. So, we checked with 8mplus evk in that also we got the same error.
we had previously worked on i.mx6(dual lite) custom board in this board we are able connect the board with JTAG. we compared all the jtag pins for working i.mx6(dual lite) with 8mplus evk and i.mx8mplus custom board
The observed jtag pin values in oscilloscope with and without jtag for I.MX8MPLUS EVK and Custom boards(both imx6 and 8mplus) are mentioned in below attached tables.


For both boards I.MX6 and I.MX8MPLUS we are using same tool and software (Arm development studio and Dstream-ST),
Questions:
1. Is there any difference for JTAG connections in I.MX6 Dual Lite and I.MX8MPLUS ?
2. we have attached the JTAG pin Values with JTAG and without JTAG connection,
Without JTAG i.mx6 and i.mx8mplus are same but after connecting JTAG,
in I.MX8MPLUS TCK and TDO are in same state before and after connecting,
but in I.MX6 Dual Lite the TCK and TDO changing see the above table Highlighted values.
Does it mean the i.mx8mplus processor is not responding to the JTAG?
3. For I.MX8MPLUS what are values will get after connecting JTAG , we had observed the above values for EVK and CUSTOM(I.MX8MP) .