7733 datasheet(265/940 Pages) RENESAS

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SERIAL I/O

7733 Group User’s Manual

8–62

8.4 Clock asynchronous serial I/O (UART) mode

Master

Slave B

Slave A

Slave D

Slave C

Data is transferred between the master

microcomputer and one specific slave

microcomputer, which is selected from

multiple slave microcomputers.

8.4.9 Sleep mode (UART0 and UART1)

This mode is used when data is transferred between the master microcomputer and one slave microcomputer,

which is selected from multiple slave microcomputers connected to the master microcomputer using UARTi.

The sleep mode is selected when the sleep selection bit (bit 7 at addresses 3016 and 3816) is set to “1”

at receiving.

In the sleep mode, the receive operation is performed when the MSB (D8 when the transfer data has a

length of 9 bits; D7 when the transfer data has a length of 8 bits; D6 when the transfer data has a length

of 7 bits) of the receive data = “1.” The receive operation is not performed when the MSB = “0.” (The UARTi

receive register’s contents is not transferred to the UARTi receive buffer register. The receive completion

flag and error flags do not change and a UARTi receive interrupt request does not occur, also.)

A usage example of the sleep mode when the transfer data has a length of 8 bits is described below.

Set the same transfer data format for the master and slave microcomputers. Select the sleep mode for

the slave microcomputer.

Transmit the data, which has “1” in bit 7 and the address of the slave microcomputer to be communicated

in bits 6 to 0, from the master microcomputer to all slave microcomputers.

All slave microcomputers receive data in operation . (At this time, a UARTi receive interrupt request

occurs.)

For all slave microcomputers, check in the interrupt routine whether bits 6 to 0 in the receive data match

their own addresses.

For the slave microcomputer whose address matches bits 6 to 0 in the receive data, terminate the sleep

mode. (Do not terminate the sleep mode for the other slave microcomputers.)

By performing operations to , “the slave microcomputer which performs transmission” can be specified.

Transmit the data, which has “0” in bit 7, from the master microcomputer. (Only the microcomputer

selected by operations to receives this data. The other microcomputers do not receive this data.)

By repeating operation , data is transferred between two specific microcomputers in succession. Also,

by performing operations to , another slave microcomputer can be specified.

Fig. 8.4.13 Sleep mode

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