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SERIAL I/O
7.4 Clock asynchronous serial I/O (UART) mode
7.4.8 Sleep mode
This mode is used to transfer data between the specified microcomputers, which are connected by using
UARTi. The sleep mode is selected by setting the sleep select bit (bit 7 at addresses 30
receiving.
In the sleep mode, receive operation is performed when the MSB (D
bits, D
when it is 8 bits, D
7
when the MSB is "0." (The UARTi receive register's contents are not transferred to the UARTi receive
buffer register. Additionally, the receive complete flag and error flags do not change and the UARTi receive
interrupt request does not occur.)
The following shows an usage example of sleep mode when the transfer data length is 8 bits.
Set the same transfer data format for the master and slave microcomputers. Select the sleep mode for
the slave microcomputers.
Transmit data, which has "1" in bit 7 and the address of the slave microcomputer with which communicates
in bits 0 to 6, from the master microcomputer to all slave microcomputers.
All slave microcomputers receive data of step
occurs.)
In all slave microcomputers, check in the interrupt routine whether bits 0 to 6 in the receive data match
their addresses.
In the slave microcomputer of which address matches bits 0 to 6 in the receive data, clear the sleep
mode. (Do not clear the sleep mode for the other slave microcomputers.)
By performing steps
Transmit data, which has "0" in bit 7, from the master microcomputer. (Only the microcomputer specified
in steps
to
can receive this data. The other microcomputers do not receive this data.)
By repeating step
communicating with another microcomputer, perform steps
microcomputer.
Slave A
Fig. 7.4.12 Sleep mode
7–52
when it is 7 bits) of the receive data is "1." Receive operation is not performed
6
to
, "specification of the microcomputer performing transfer" is realized.
, transfer can be performed between the same microcomputers continuously. When
Master
Slave B
7751 Group User's Manual
8
. (At this time, the UARTi receive interrupt request
to
Transfer data between the master
microcomputer and one slave microcomputer
selected from multiple slave microcomputers.
Slave C
, 38
16
16
when the transfer data length is 9
in order to specify the new slave
Slave D
) to "1" when
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