Section 13 Serial Communication Interface (SCI)
Rev. 1.00 Mar. 12, 2008 Page 460 of 1178
REJ09B0403-0100
13.5 Multiprocessor
Communication Function
Use of the multiprocessor communication function enables data transfer to be performed among a
number of processors sharing communication lines by means of asynchronous serial
communication using the multiprocessor format, in which a multiprocessor bit is added to the
transfer data. 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 for
the specified receiving station. The multiprocessor bit is used to differentiate between the ID
transmission cycle and the data transmission cycle. If the multiprocessor bit is 1, the cycle is an ID
transmission cycle, and if the multiprocessor bit is 0, the cycle is a data transmission cycle. Figure
13.10 shows an example of inter-processor communication using the multiprocessor format. The
transmitting station first sends the ID code 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. 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 data until data with a 1
multiprocessor bit is again received.
The SCI uses the MPIE bit in SCR to implement this function. When the MPIE bit is set to 1,
transfer of receive data from RSR to RDR, error flag detection, and setting the RDRF, FER, and
ORER status flags in SSR to 1 are prohibited until data with a 1 multiprocessor bit is received. On
reception of a receive character with a 1 multiprocessor bit, the MPB bit in SSR is set to 1 and the
MPIE bit is automatically cleared, thus normal reception is resumed. If the RIE bit in SCR is set to
1 at this time, an RXI interrupt is generated.
When the multiprocessor format is selected, the parity bit setting is invalid. All other bit settings
are the same as those in normal asynchronous mode. The clock used for multiprocessor
communication is the same as that in normal asynchronous mode.
Summary of Contents for H8S Family
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Page 70: ...Section 1 Overview Rev 1 00 Mar 12 2008 Page 22 of 1178 REJ09B0403 0100...
Page 108: ...Section 2 CPU Rev 1 00 Mar 12 2008 Page 60 of 1178 REJ09B0403 0100...
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Page 206: ...Section 6 Bus Controller BSC Rev 1 00 Mar 12 2008 Page 158 of 1178 REJ09B0403 0100...
Page 420: ...Section 9 14 Bit PWM Timer PWMX Rev 1 00 Mar 12 2008 Page 372 of 1178 REJ09B0403 0100...
Page 476: ...Section 12 Watchdog Timer WDT Rev 1 00 Mar 12 2008 Page 428 of 1178 REJ09B0403 0100...
Page 552: ...Section 14 CRC Operation Circuit CRC Rev 1 00 Mar 12 2008 Page 504 of 1178 REJ09B0403 0100...
Page 712: ...Section 18 I2 C Bus Interface IIC Rev 1 00 Mar 12 2008 Page 664 of 1178 REJ09B0403 0100...
Page 804: ...Section 19 LPC Interface LPC Rev 1 00 Mar 12 2008 Page 756 of 1178 REJ09B0403 0100...
Page 838: ...Section 20 Ethernet Controller EtherC Rev 1 00 Mar 12 2008 Page 790 of 1178 REJ09B0403 0100...
Page 964: ...Section 24 RAM Rev 1 00 Mar 12 2008 Page 916 of 1178 REJ09B0403 0100...
Page 1066: ...Section 25 Flash Memory Rev 1 00 Mar 12 2008 Page 1018 of 1178 REJ09B0403 0100...
Page 1098: ...Section 26 Boundary Scan JTAG Rev 1 00 Mar 12 2008 Page 1050 of 1178 REJ09B0403 0100...
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