MPC5604B/C Microcontroller Reference Manual, Rev. 8
Freescale Semiconductor 209
source event (except the power-on reset event) to be converted from a reset to either a SAFE mode request
issued to the MC_ME or to an interrupt request issued to the core.
Alternate event selection for a given reset source is made via the RGM_F/DERD and RGM_F/DEAR
registers as shown in Table 9-13.
The alternate event is cleared by deasserting the source of the request (i.e. at the reset source that caused
the alternate request) and also clearing the appropriate RGM_F/DES status bit.
NOTE
Alternate requests (SAFE mode as well as interrupt requests) are generated
asynchronously.
NOTE
If a masked ‘destructive’ reset event which is configured to generate a
SAFE mode/interrupt request occurs during PHASE0, it is ignored, and the
MC_RGM will not send any safe mode/interrupt request to the MC_ME.
The same is true for masked ‘functional’ reset events during PHASE1.
9.4.7 Boot Mode Capturing
The MC_RGM provides sampling of the boot mode PA[8] and PA[9] for use by the system to determine
the boot mode. This sampling is done five fast internal RC oscillator (16 MHz) clock cycles before the
rising edge of RESET. The result of the sampling is then provided to the system. For each bit, a value of
‘1’ is produced only if each of the oldest three of the five samples have the value ‘1’, otherwise a value of
‘0’ is produced.
NOTE
In order to ensure that the boot mode is correctly captured, the application
needs to apply the valid boot mode value to the device at least five fast
internal RC oscillator (16 MHz) clock periods before the external reset
deassertion crosses the V
IH
threshold.
NOTE
RESET can be low as a consequence of the internal reset generation. This
will force re-sampling of the boot mode pins.
Table 9-13. MC_RGM Alternate Event Selection
RGM_F/DERD
Bit Value
RGM_F/DEAR
Bit Value
Generated Event
0 X reset
1 0 SAFE mode request
1 1 interrupt request
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