HD6417034B RENESAS [Renesas Technology Corp], HD6417034B Datasheet - Page 415

• Manufacturer Part Number: HD6417034B
• Description: 32-Bit RISC Microcomputer
• Manufacturer: RENESAS [Renesas Technology Corp]

13.3.3
The multiprocessor communication function enables several processors to share a single serial
communication line. The processors communicate in asynchronous mode using a format with an
additional multiprocessor bit (multiprocessor format).
In multiprocessor communication, each receiving processor is addressed by a unique ID. A serial
communication cycle consists of an ID-sending cycle that identifies the receiving processor, and a
data-sending cycle. The multiprocessor bit distinguishes ID-sending cycles from data-sending
cycles. The transmitting processor starts by sending the ID of the receiving processor with which it
wants to communicate as data with the multiprocessor bit set to 1. Next the transmitting processor
sends transmit data with the multiprocessor bit cleared to 0.
Receiving processors skip incoming data until they receive data with the multiprocessor bit set to
1. When they receive data with the multiprocessor bit set to 1, receiving processors compare the
data with their IDs. The receiving processor with a matching ID continues to receive further
incoming data. Processors with IDs not matching the received data skip further incoming data
until they again receive data with the multiprocessor bit set to 1. Multiple processors can send and
receive data in this way.
Figure 13.9 shows an example of communication between processors using the multiprocessor
format.
Figure 13.8 Example of SCI Receive Operation (8-Bit Data with Parity and One Stop Bit)
TDRE
Serial
FER
data
Multiprocessor Communication
1
Start
bit
0
D
0
D
1
1 frame
Data
D
7
Parity
bit
0/1
RXI request
Stop
bit
1
Section 13 Serial Communication Interface (SCI)
Start
bit
0
and clears RDRF to 0
RXI interrupt handler
reads data in RDR
D
0
Rev. 7.00 Jan 31, 2006 page 389 of 658
D
1
Data
D
7
Parity
bit
0/1
Framing error,
ERI request
Stop
bit
REJ09B0272-0700
0
Idle (mark)
1
state