Datasheet

Section 15 Controller Area Network for Tiny (TinyCAN)
Rev. 4.00 Mar. 15, 2006 Page 330 of 556
REJ09B0026-0400
4. If an arbitration loss occurs in the arbitration field, the TinyCAN starts reception. When the
DART or MBn bit in TXCR is set to 1, a transmit request for message 1 is canceled. At this
time, the MBn bits in TXPR and TXCR are cleared to 0 and the MBn bit in ABACK and the
EMPI bit in TCIRR1 are set to 1. The MBn bit in TXACK is always 0.
5. When there is a transmit request after reception has completed (for details, see section 15.5.4,
Message Reception), the arbitration for message 2 is determined and it is transmitted to the
CAN bus. When there is no transmit request, the TinyCAN starts reception.
HRXD
SOF
Bus idle
Bus idle
Arbitration Control Data
Message 1
[4] Arbitration loss
Transmission for message 1
cannot be cancelled by TXCR
Internal arbitration for message 2 can be configurable
(Transmission settings can be changed by TXPR/TXCR)
Message 1 reception
Transmission for message 2
cannot be cancelled by TXCR
Internal arbitration for message 3
can be configurable
[5] Internal arbitration for message 2
is determined after normal reception
has completed
[3] Internal arbitration for message 1
is determined
[2] Set TXPR
Message 2
Message 2
CRC ACK EOF
Intermission
SOF
SOF Arbitration
ACK bit
Intermission
SOF
HTXD
MBn in TXPR
MBn in TXCR
EMPI in TCIRR1
MBn in ABACK
DART
Figure 15.8 Internal Arbitration at Reception Caused by CAN Bus Arbitration Loss
(MBn in TXCR = 0 and DART = 0)