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C165H
IOM-2 Interface Controller
Data Sheet
315
2001-04-19
PRELMNARY
a recommended software timer (GPT) expires
A reception is aborted by the C165H if
an abort request from the transmitting device occurs, see
Figure 107
. This abort
request has basically the same waveform as an end of transmission, see
Figure 108
.
Note:
In case the C165H does not detect identical monitor messages in two successive
frames, transmission is not aborted. Instead the C165H will wait until two identical
bytes are received in succession.
-EXCERPT-
The internal MX,MR control indicates or acknowledges a new byte in the MON slot by
toggling MX,MR from the active to the inactive state for one frame.
Two frames with the MX-bit in the inactive state indicate the
end of transmission
.
Two frames with the MR-bit set to inactive indicate a receiver request for
abort
(see
Chapter 14.3.2).
The transmitter can
delay a transmission
sequence by sending the same byte
first byte occurrence.
Since a
double last-look criterion
is implemented the receiver is able to receive the
MON slot data at least twice (in two consecutive frames). The receiver acknowledge
the data after the reception of two identical bytes in two successive frames.
To control this handshake procedure a collision detection mechanism is implemented
in the transmitter. This is done by making a
collision check
per bit on the transmitted
MONITOR data and the MX bit.
Monitor data will be transmitted repeatedly until its reception is acknowledged or the
transmission time-out timer expires.
Two frames with the MX bit in the inactive state indicates the
end of a message
(EOM).
MONITOR control commands are processed sequential that means e.g. during a read
on a register no further command is executed.
14.3.2
Abort Procedure
During a transmission process, it is possible for the receiver to ask a transmission to be
aborted by sending an inactive MR bit value in two consecutive frames. This is effected
by the microcontroller writing the MR control bit MRC to ’0’. An aborted transmission is
indicated by a MONITOR Channel Data Abort MAB interrupt status at the transmitter.
The MX/MR bits are under control of the microcontroller through MXC or MRC
respectively. An abort is indicated by an MAB interrupt or MER interrupt respectively.
A transmission is aborted by the C165H if
abort request from receiver is detected (see
Figure 106
)
a collision on the IOM bus of the MONITOR data or MX bit occurs