Sometimes you want to disable the JTAG access on a
device to avoid any debug access to the device. This
can be done by using the JTAGLOCK feature on this
device. You need to follow a two step process to
enable the JTAGLOCK feature (both steps can be
performed at the same time).
- Program the JTAG passwords. This device has a
128-bit JTAG password that needs to be programmed
in Z1 USER OTP. JTAG passwords are split into two
parts, JTAGPSWDH and JTAGPSWDL. JTAGPSWDH is part
of Z1 USER OTP header and JTAGPSWDL is part of Z1
Zone Select Block (ZSB). What this means is
program JTAGPSWDH once and change the JTAGPSWDL
multiple times, if needed. Code Composer Studio
has an integrated tool that you need to use to
unlock the JTAGLOCK on device.
- After programming the JTAG passwords, you need to
enable the JTAGLOCK module (JLM) by programming
bit [3:0] of Z1OTP_JLM_ENABLE with any value other
than 0xF. It is recommended to program all four
bits with a value 0x0.