Datasheet

Section 16 Serial Communication Interface (SCI, IrDA)
(The H8S/2695 is not equipped with an IrDA function)
Page 770 of 1434 R01UH0166EJ0600 Rev. 6.00
Mar 02, 2011
H8S/2633 Group, H8S/2633 F-ZTAT
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H8S/2633R F-ZTAT
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16.3.3 Multiprocessor Communication Function
The multiprocessor communication function performs serial communication using the
multiprocessor format, in which a multiprocessor bit is added to the transfer data, in asynchronous
mode. Use of this function enables data transfer to be performed among a number of processors
sharing transmission lines.
When multiprocessor communication is carried out, each receiving station is addressed by a
unique ID code.
The serial communication cycle consists of two component cycles: an ID transmission cycle
which specifies the receiving station, and a data transmission cycle. The multiprocessor bit is used
to differentiate between the ID transmission cycle and the data transmission cycle.
The transmitting station first sends the ID of the receiving station with which it wants to perform
serial communication as data with a 1 multiprocessor bit added. It then sends transmit data as data
with a 0 multiprocessor bit added.
The receiving station skips the data until data with a 1 multiprocessor bit is sent.
When data with a 1 multiprocessor bit is received, the receiving station compares that data with its
own ID. The station whose ID matches then receives the data sent next. Stations whose ID does
not match continue to skip the data until data with a 1 multiprocessor bit is again received. In this
way, data communication is carried out among a number of processors.
Figure 16.9 shows an example of inter-processor communication using the multiprocessor format.
Data Transfer Format
There are four data transfer formats.
When the multiprocessor format is specified, the parity bit specification is invalid.
For details, see table 16.10.