SERIAL I/O
11.3 Clock synchronous serial I/O mode
[When using interrupts]
[When not using interrupts]
A UARTi transmit interrupt request occurs
when the transbission starts (when the
UARTi transmit buffer register becomes
empty).
Checking state of UARTi transmit buffer register
UART0 transmit/receive control register 1 (Address 3516
)
UART1 transmit/receive control register 1 (Address 3D16
)
UARTi transmit interrupt
b7
b0
b0
1
Transmit buffer empty flag
0: Data is present in transmit buffer register.
1: No data is present in transmit buffer register.
(Writing of next transmit data is possible.)
Note:
This figure shows the bits and registers required
for processing.
Writing of next transmit data
See Figures 11.3.6 and 11.3.7 for the change of
flag state and the occurrence timing of an interrupt
request.
UART0 transmit buffer register (Address 3216
UART1 transmit buffer register (Address 3A16
)
)
b7 b0
Transmit data is set.
Fig. 11.3.3 Write operation of data after transmission start
[When using interrupts]
[When not using interrupts]
Checking start of transmission
A UARTi transmit interrupt request
occurs when the transmission starts.
UART0 transmit interrupt control register (Address 7116
UART1 transmit interrupt control register (Address 7316
)
)
UARTi transmit interrupt
b7
b
0
Interrupt request bit
0: No interrupt requested
1: Interrupt requested
(Transmission has started.)
Note:
This figure shows the bits and registers required
for processing.
Checking completion of transmission
UART0 transmit/receive control register 0 (Address 3416
UART1 transmit/receive control register 0 (Address 3C16
)
)
See Figures 11.3.6 and 11.3.7 for the change
of flag state and the occurrence timing of an
interrupt request.
b0
b7
Transmit register empty flag
0: Transmission is in progress.
1: Transmission is completed.
Processing at completion of transmission
Fig. 11.3.4 Detect operation of transmit completion
7906 Group User’s Manual Rev.2.0
11-25
RENESAS [ RENESAS TECHNOLOGY CORP ]
