PXR40RM Datasheet, PDF (298/1434 Pages) Freescale Semiconductor, Inc – PXR40 Microcontroller

Boot Assist Module (BAM)
Censored Flash Array
64-bit Password
Compare
Enable/disable
Other Nexus Clients
• eDMA
• e200z7 core
.
.
.
Nexus client
TAP controller
JTAG Port Controller
64-bit Password
CENSOR_CTRL register
Debug/Calibration Tool
Access
Figure 9-8. Enabling JTAG/Nexus port access on a censored device
The steps to enable the debug port on a censored device are as follows:
1. After the RSTOUT pin has is negated, hold the device in system reset state using a debugger or
other tool.
2. While the device is being held in system reset state shift the 64-bit password into the
CENSOR_CTRL register (see Section 32.3.4, CENSOR_CTRL Register) via the JTAG port using
the JTAG ENABLE_CENSOR_CTRL instruction. The JTAG serial password is compared against
the serial boot flash password from the flash shadow block.
3. If there is a match the Nexus client TAP controller enters normal operation mode and the DISNEX
flag in the SIU_CCR register is negated, indicating Nexus is enabled. Upon negation of reset the
debug / calibration tool is able to access the device via NEXUS port and JTAG. If the JTAG serial
password does not match the serial boot flash password or the serial boot flash password is an
illegal password then the debug / calibration tool is not able to access the device.
After the debug port is enabled, the tool can access the censored device and can erase and
reprogram the shadow flash block in order to uncensor the device.
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PXR40 Microcontroller Reference Manual, Rev. 1
Freescale Semiconductor