MC908GZ60CFUE Datasheet, PDF (145/352 Pages) Freescale Semiconductor, Inc – Standard features, Features of the CPU08

Low-Power Modes
.
Table 12-2. MSCAN08 versus CPU Operating Modes
MSCAN08 Mode
Power Down
Sleep
Soft Reset
Normal
1. ‘X’ means don’t care.
STOP
SLPAK = X⁽¹⁾
SFTRES = X
CPU Mode
WAIT or RUN
SLPAK = 1
SFTRES = 0
SLPAK = 0
SFTRES = 1
SLPAK = 0
SFTRES = 0
12.8.1 MSCAN08 Sleep Mode
The CPU can request the MSCAN08 to enter the low-power mode by asserting the SLPRQ bit in the
module configuration register (see Figure 12-7). The time when the MSCAN08 enters sleep mode
depends on its activity:
• If it is transmitting, it continues to transmit until there is no more message to be transmitted, and
then goes into sleep mode
• If it is receiving, it waits for the end of this message and then goes into sleep mode
• If it is neither transmitting or receiving, it will immediately go into sleep mode
NOTE
The application software must avoid setting up a transmission (by clearing
or more TXE flags) and immediately request sleep mode (by setting
SLPRQ). It then depends on the exact sequence of operations whether
MSCAN08 starts transmitting or goes into sleep mode directly.
MSCAN08 RUNNING
MCU
SLPRQ = 0
or MSCAN08
SLPAK = 0
MCU
MSCAN08 SLEEPING
SLPRQ = 1
SLPAK = 1
SLEEP REQUEST
SLPRQ = 1
SLPAK = 0
MSCAN08
Figure 12-7. Sleep Request/Acknowledge Cycle
MC68HC908GZ60 • MC68HC908GZ48 • MC68HC908GZ32 Data Sheet, Rev. 6
Freescale Semiconductor
145