MC68HC05X4 Datasheet, PDF (81/156 Pages) Motorola, Inc – HCMOS Microcontroller Unit

Freescale Semiconductor, Inc.
Motorola CAN
Interface to the MC68HC05X4 CPU
RRB — Release receive buffer
When set this releases the receive buffer currently attached to the
CPU, allowing the buffer to be reused by the MCAN. This may result
in another message being received, which could cause another
receive interrupt request (if RIE is set). This bit is cleared
automatically when a message is received, i.e. when the RS bit (see
MCAN status register (CSTAT)) becomes set.
1 = Released – receive buffer is available to the MCAN.
0 = No action.
AT — Abort transmission
When this bit is set a pending transmission will be cancelled if it is not
already in progress, allowing the transmit buffer to be loaded with a
new (higher priority) message when the buffer is released. If the CPU
tries to write to the buffer when it is locked, the information will be lost
without being signalled. The status register can be checked to see if
transmission was aborted or is still in progress.
1 = Present – Abort transmission of any pending messages.
0 = No action.
TR — Transmission request
1 = Present – Depending on the transmission buffer’s content, a
data frame or a remote frame will be transmitted.
0 = No action. This will not cancel a previously requested
transmission; the abort transmission command must be used
to do this.
13-mcan
MOTOROLA
Motorola CAN
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MC68HC05X4 Rev 1.0
81