Exiting Wir Mode; Master And Control Subsystem Wir Mode Flow - Texas Instruments Concerto F28M35 Series Technical Reference Manual

WIR Mode

1.4.2 Exiting WIR Mode

As explained earlier, after the master subsystem and/or control subsystem enter WIR mode, they stay in
this mode as long as the EMU0 and EMU1 bits in the respective WIR register are set to match the
WIR_MODE_YES value. If they do not match the WIR_MODE_YES value, then the boot ROM continues
its execution by exiting the WIR mode. Although both the boot ROMs in the master subsystem and control
subsystem continue to read the WIR mode register, they do not force the EMU0 and EMU1 bits to re-latch
the EMU0 and EMU1 pin status by setting the sample bits. So in order to force re-latching of the EMU0
and EMU1 bits of WIR mode registers, the user has to give an XRS reset or has to set the re-sample bit
from the debugger.
Below are different options for bringing the device out of WIR mode after it enters the mode.
• Set EMU0 and EMU1 pins on the device to a value other than the WIR_MODE_YES value as shown
in Table 1-7 and give an XRS reset to the device. Refer to the device-specific data manual for more
details on the pin locations.
• EMU0 and EMU1 bits in MWIR and CWIR registers are R/W type bits and are reset to the actual state
of EMU0 and EMU1 pins on XRS reset or whenever the sample bit is set in the respective WIR
registers to re-sample these pins. The user can then directly write a value other than the
WIR_MODE_YES value (refer to
94
System Control and Interrupts
Figure 1-2. Master and Control Subsystem WIR Mode Flow
Master Subsystem Reset Released
(go to M-bootROM)
Release Control subsystem out of reset
Read MWIR Register
WIR Mode Enabled When
Latched EMU0 == 0
Latched EMU1 == 1
WIR Mode ?
no
Continue With
M-bootROM Procedure
Control Subsystem Reset Released
(go to C-BootROM)
Read CWIR Register
WIR Mode Enabled When
Latched EMU0 == 0
Latched EMU1 == 1
WIR Mode ?
no
Continue With
C28 Boot Procedure
Table 1-7) to these bits, and not set the sample bit. Therefore, when
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yes Read MWIR Register
no
WIR Mode ?
yes
Read CWIR Register
no
WIR Mode ?
SPRUH22I – April 2012 – Revised November 2019
www.ti.com
yes
yes
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