Datasheet

Section 15 Controller Area Network for Tiny (TinyCAN)
Rev. 4.00 Mar. 15, 2006 Page 332 of 556
REJ09B0026-0400
HRXD
[5] Overwrite DART bit for message 2
[4] Clear MBn bit in TXPR for message 1
[2] Set TXPR
[3] Load DART bit when message 1
is transferred to temporary buffer
HTXD
DART
TXPR.MBn
TXCR.MBn
ABACK.MBn
TCIRR.EMPI
TXACK.MBn
Transmission for message 1
cannot be cancelled by TXCR
Message 1 reception
Transmission for message 2
cannot be cancelled by TXCR
Internal arbitration for message 2 can be configurable
(Transmission settings can be changed by TXPR/TXCR)
SOF Arbitration Control Data CRC ACK EOF
Intermission
SOF
SOF Arbitration
ACK Bit
Internal arbitration for message 3
can be configurable
[5] Internal arbitration for message 2
is determined after normal reception
has completed
If other Mailbox has a transmit
request, transmission is started at this
timing
[4] Set MBn in ABACK and EMPI in TCIRR1 for message 1
Message 1
[4] Arbitration loss
Message 2
Bus idle
Bus idle
Figure 15.10 Internal Arbitration at Reception Caused by CAN Bus Arbitration Loss
(DART = 1)
CAN Bus Error: Figures 15.11 to 15.13 show timings for internal arbitration caused by an error
on the CAN bus. Procedure and operation are as follows.
1. Write data of a transmit message to MCn0, MCn4 to MCn7, and MDn0 to MDn7 [n = 1 to 3]
before clearing the MBn bit in MBCR corresponding to the Mailbox of the transmit message to
0 (initial setting).
2. Set the MBn bit in TXPR to 1 (start condition issuance). Then, the start condition is generated.
3. The internal arbitration for message 1 is determined and the transmit message is transferred to
the temporary buffer. After that, even if a transmit request cancellation is issued to the message
being transmitted by the DART or MBn bit in TXCR, message 1 is transmitted continuously
unless the TinyCAN detects an arbitration loss or error on the CAN bus.