NXP Semiconductors MWCT101 S Series, Reference Manual

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49.5.5 Receive process under Pretended Networking mode
Pretended Networking mode adds specific wakeup functionality in low power mode
(Stop mode). When Pretended Networking mode (PN) is enabled by asserting
MCR[PNET_EN], FlexCAN continues processing Rx CAN messages under low power
mode, and is able to detect specific wakeup messages by filtering them against ID and
payload target values using preselected matching criteria. Wakeup functionality is not
available for messages in CAN FD format. When in Pretended Networking mode, CAN
FD format messages are ignored.
PN registers are located in the 0x0B00–0B7C address range and can be written only in
Freeze mode. These registers are used for writing PN configuration (both control and
target values) prior to entering Pretended Networking mode, and for reading wakeup
flags and the received message ID and data when returning back to normal mode after
wakeup. The CPU must wait for MCR[LPMACK] to be negated before performing any
access to FlexCAN PN registers.
PN control registers are described in Pretended Networking Control 1 Register
(CTRL1_PN) and Pretended Networking Control 2 Register (CTRL2_PN). The control
bit fields that configure the filtering criteria are:
• PLFS: payload filtering selection
• IDFS: ID filtering selection
• FCS: filtering combination selection
PN target values are:
• FLT_IDE: IDE target value used to filter the incoming message by its format
(standard or extended).
• FLT_RTR: RTR target value used to filter the incoming message by its type (data or
remote frame).
• FLT_DLC_HI and FLT_DLC_LO: target DLC range used to filter the size of
payload part of an incoming message.
• FLT_ID1: ID target value used to filter the incoming message ID (equal to, smaller
than or equal, greater than or equal, or the lower limit value in an ID range).
• FLT_ID2: ID target value used as the upper limit in an ID range.
• PL1: Payload target value used to filter the incoming message payload (equal to,
smaller than or equal, greater than or equal, or the lower limit value in a payload
range).
• PL2: Payload target value used as the upper limit in a payload range.
Chapter 49 FlexCAN
MWCT101xS Series Reference Manual, Rev. 3, 07/2019
NXP Semiconductors 1669