Datasheet

UM10398 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2014. All rights reserved.
User manual Rev. 12.3 — 10 June 2014 287 of 547
NXP Semiconductors
UM10398
Chapter 16: LPC111x/LPC11Cxx C_CAN controller
Remark: The busoff recovery sequence (see CAN Specification Rev. 2.0) cannot be
shortened by setting or resetting the INIT bit. If the device goes into busoff state, it will set
INIT, stopping all bus activities. Once INIT has been cleared by the CPU, the device will
then wait for 129 occurrences of Bus Idle (129  11 consecutive HIGH/recessive bits)
before resuming normal operations. At the end of the busoff recovery sequence, the Error
Management Counters will be reset.
During the waiting time after the resetting of INIT, each time a sequence of 11
HIGH/recessive bits has been monitored, a Bit0Error code is written to the Status Register
CANSTAT, enabling the CPU to monitor the proceeding of the busoff recovery sequence
and to determine whether the CAN bus is stuck at LOW/dominant or continuously
disturbed.
16.6.1.2 CAN status register
A status interrupt is generated by bits BOFF, EWARN, RXOK, TXOK, or LEC. BOFF and
EWARN generate an error interrupt, and RXOK, TXOK, and LEC generate a status
change interrupt if EIE and SIE respectively are set to enabled in the CANCTRL register.
A change of bit EPASS and a write to RXOK, TXOK, or LEC will never create a status
interrupt.
Reading the CANSTAT register will clear the Status Interrupt value (0x8000) in the
CANINT register.