HD6433636SW datasheet(276/418 Pages) RENESAS

276 / 418 page

262

Notes: 1. To switch from transmitting to simultaneous transmitting and receiving, first confirm

that TDRE and TEND are both set to 1 and that SCI3 has finished transmitting. Next

clear TE to 0. Then set both TE and RE to 1.

2. To switch from receiving to simultaneous transmitting and receiving, after confirming

that SCI3 has finished receiving, clear RE to 0. Next, after confirming that RDRF and

the error flags (OER FER, PER) are all 0, set both TE and RE to 1.

10.3.6

Multiprocessor Communication Function

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 an ID code. A serial

communication cycle consists of two cycles: an ID-sending cycle that identifies the receiving

processor, and a data-sending cycle in which communication data is sent to the specified receiving

processor. The multiprocessor bit is used to distinguish between the ID-sending cycle and the

data-sending cycle. The multiprocessor bit is 1 in an ID-sending cycle, and 0 in a data-sending

cycle.

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. When a receiving processor receives data

with the multiprocessor bit set to 1, it compares the data with its own ID. If the data matches its

ID, the receiving processor continues to receive incoming data. If the data does not match its ID,

the receiving processor skips further incoming data until it again receives data with the

multiprocessor bit set to 1. Multiple processors can send and receive data in this way.

Figure 10.19 shows an example of communication among different processors using a

multiprocessor format.

HD6433636SW Folha de dados(PDF) 276 Page - Renesas Technology Corp