Atmel Xplained Pro Evaluation Kit ATSAM4E-XPRO ATSAM4E-XPRO Data Sheet
Product codes
ATSAM4E-XPRO
667
SAM4E [DATASHEET]
Atmel-11157D-ATARM-SAM4E16-SAM4E8-Datasheet_12-Jun-14
Figure 33-8.
Enabling Low-power Mode
33.7.5.2 Disabling Low-power Mode
The CAN controller can be awake after detecting a CAN bus activity. Bus activity detection is done by an external
module that may be embedded in the chip. When it is notified of a CAN bus activity, the software application
disables Low-power Mode by programming the CAN controller.
module that may be embedded in the chip. When it is notified of a CAN bus activity, the software application
disables Low-power Mode by programming the CAN controller.
To disable Low-power Mode, the software application must:
̶
Enable the CAN Controller clock. This is done by programming the Power Management Controller
(PMC).
(PMC).
̶
Clear the LPM field in the CAN_MR
The CAN controller synchronizes itself with the bus activity by checking for eleven consecutive “recessive” bits.
Once synchronized, the WAKEUP signal in the CAN_SR is set.
Once synchronized, the WAKEUP signal in the CAN_SR is set.
Depending on the corresponding mask in the CAN_IMR, an interrupt is generated while WAKEUP is set. The
SLEEP signal in the CAN_SR is automatically cleared once WAKEUP is set. WAKEUP signal is automatically
cleared once SLEEP is set.
SLEEP signal in the CAN_SR is automatically cleared once WAKEUP is set. WAKEUP signal is automatically
cleared once SLEEP is set.
If no message is being sent on the bus, then the CAN controller is able to send a message eleven bit times after
disabling Low-power Mode.
disabling Low-power Mode.
If there is bus activity when Low-power mode is disabled, the CAN controller is synchronized with the bus activity
in the next interframe. The previous message is lost (see
in the next interframe. The previous message is lost (see
).
SLEEP
(CAN_SR)
MRDY
(CAN_MSR1)
LPM
(CAN_MR)
LPEN= 1
CAN BUS
MRDY
(CAN_MSR3)
Mailbox 1
Mailbox 3
Arbitration lost
WAKEUP
(CAN_SR)
0x0
CAN_TIM