56F8366_07 Datasheet, PDF (133/184 Pages) Freescale Semiconductor, Inc – 16-bit Digital Signal Controllers

6.8 Stop and Wait Mode Disable Function
Stop and Wait Mode Disable Function
Permanent
Disable
D
Q
D-FLOP
C
56800E
Reprogrammable
Disable
D
Q
D-FLOP
STOP_DIS
Clock
Select
Reset
CR
Note: Wait disable circuit is
similar
Figure 6-17 Internal Stop Disable Circuit
The 56800E core contains both STOP and WAIT instructions. Both put the CPU to sleep. For lowest
power consumption in Stop mode, the PLL can be shut down. This must be done explicitly before entering
Stop mode, since there is no automatic mechanism for this. When the PLL is shut down, the 56800E
system clock must be set equal to the prescaler output.
Some applications require the 56800E STOP and WAIT instructions be disabled. To disable those
instructions, write to the SIM control register (SIM_CONTROL) described in Part 6.5.1. This procedure
can be on either a permanent or temporary basis. Permanently assigned applications last only until their
next reset.
6.9 Resets
The SIM supports four sources of reset. The two asynchronous sources are the external RESET pin and
the Power-On Reset (POR). The two synchronous sources are the software reset, which is generated within
the SIM itself by writing to the SIM_CONTROL register, and the COP reset.
Reset begins with the assertion of any of the reset sources. Release of reset to various blocks is sequenced
to permit proper operation of the device. A POR reset is first extended for 2²¹ clock cycles to permit
stabilization of the clock source, followed by a 32 clock window in which SIM clocking is initiated. It is
then followed by a 32 clock window in which peripherals are released to implement Flash security, and,
finally, followed by a 32 clock window in which the core is initialized. After completion of the described
reset sequence, application code will begin execution.
Resets may be asserted asynchronously, but they are always released internally on a rising edge of the
system clock.
56F8366 Technical Data, Rev. 6
Freescale Semiconductor
133
Preliminary