Functional Operation
17-38
ADSP-BF50x Blackfin Processor Hardware Reference
CAN Built-In Sleep Mode
The next level of power savings can be realized by using the CAN mod-
ule’s built-in sleep mode. This mode is entered by setting the sleep mode
request (
SMR
) bit in the
CAN_CONTROL
register. The module enters the sleep
mode after the current operation of the CAN bus is finished. Once this
mode is entered, many of the internal CAN module clocks are shut off,
reducing power consumption, and the sleep mode acknowledge (
SMACK
)
bit is set in
CAN_INTR
. When the CAN module is in sleep mode, all register
reads return the contents of
CAN_INTR
instead of the usual contents. All
register writes, except to
CAN_INTR
, are ignored in sleep mode.
A small part of the module is clocked continuously to allow for wakeup
out of sleep mode. A write to the
CAN_INTR
register ends sleep mode. If the
WBA
bit in the
CAN_CONTROL
register is set before entering sleep mode, a
dominant bit on the
CANRX
pin also ends sleep mode.
CAN Wakeup From Hibernate State
For greatest power savings, the Blackfin processor provides a hibernate
state, where the internal voltage regulator shuts off the internal power sup-
ply to the chip, turning off the core and system clocks in the process. In
this mode, the only power drawn (roughly 50
A) is that used by the
regulator circuitry awaiting any of the possible hibernate wakeup events.
One such event is a wakeup due to CAN bus activity. After hibernation,
the CAN module must be re-initialized.
For low power designs, the external CAN bus transceiver is typically put
into standby mode via one of the Blackfin processor’s general purpose I/O
pins. While in standby mode, the CAN transceiver continually drives the
recessive logic ‘1’ level onto the
CANRX
pin. If the transceiver then senses
CAN bus activity, it will, in turn, drive the
CANRX
pin to the dominant
logic ‘0’ level. This signals to the Blackfin processor that CAN bus activity
has been detected. If the internal voltage regulator is programmed to
recognize CAN bus activity as an event to exit hibernate state, the part
Содержание EZ-KIT Lite ADSP-BF506F
Страница 50: ...Contents l ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 92: ...Development Tools 1 30 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 110: ...Interface Overview 3 12 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 132: ...Unique Information for the ADSP BF50x Processor 4 22 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 236: ...Internal Flash Memory Control Registers 6 92 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 342: ...Unique Information for the ADSP BF50x Processor 7 106 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 484: ...Unique Information for the ADSP BF50x Processor 10 60 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 493: ...ADSP BF50x Blackfin Processor Hardware Reference 11 9 Core Timer Unique Information for the ADSP BF50x Processor None ...
Страница 494: ...Unique Information for the ADSP BF50x Processor 11 10 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 506: ...Unique Information for the ADSP BF50x Processor 12 12 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 544: ...Unique Information for the ADSP BF50x Processor 13 38 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 650: ...Programming Examples 15 56 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 712: ...Unique Information for the ADSP BF50x Processor 16 62 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 804: ...Programming Examples 17 92 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 972: ...Unique Information for the ADSP BF50x Processor 20 38 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 1194: ...Programming Examples 24 90 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 1256: ...ACM Registers A 50 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 1264: ...Boundary Scan Architecture B 8 ADSP BF50x Blackfin Processor Hardware Reference ...