SERIAL I/O
11.4 Clock asynchronous serial I/O (UART) mode
[When using interrupts]
[When not using interrupts]
A UARTi transmit interrupt request occurs
when the transmission 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.)
This figure shows the bits and registers
required for processing.
Note:
Writing of next transmit data
See Figures 11.4.7 to 11.4.9 for the change
of flag state and the occurrence timing of an
interrupt request.
UART0 transmit buffer register (Addresses 3316, 3216
UART1 transmit buffer register (Addresses 3B16, 3A16
)
)
b15 b8 b7 b0
Transmit data is set.
Fig. 11.4.5 Write operation of data after transmission start
7906 Group User’s Manual Rev.2.0
11-42
RENESAS [ RENESAS TECHNOLOGY CORP ]
