7733 Datasheet, PDF (262/940 Pages) Renesas Technology Corp – 16-BIT SINGLE-CHIP MICROCOMPUTER

SERIAL I/O
8.4 Clock asynchronous serial I/O (UART) mode
8.4.6 Receive operation
When the receive enable bit is set to “1,” the UARTi enters the receive enable state. And then, the transfer
clock is generated when ST is detected, and reception is started.
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____
When the RTS function is selected (UART0, UART1), the RTSi pin’s output level becomes “L” if the UARTi
enters the receive enable state and the microcomputer informs the transmitter side that reception is
____
enabled. When reception is started, the RTSi pin’s output level becomes “H.” Accordingly, by connecting
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____
the RTSi pin (receiver side) and the CTSi pin (transmitter side), the timing of transmission and that of
reception can be matched. Figure 8.4.11 shows an connection example.
The receive operation is described below.
ΠThe signal which is input from the RxDi pin is taken in the most significant bit of the UARTi receive
register synchronously with the transfer clock’s rising edge.
 The contents of UARTi receive register is shifted by 1 bit to the right.
Ž Operations Œ and  are repeated at each transfer clock’s rising edge.
 When a set of data is prepared, in other words, when shifted several times depending on the specified
data format, the UARTi receive register’s contents is transferred to the UARTi receive buffer register.
 Simultaneously with , the receive completion flag is set to “1.” Furthermore, a UARTi receive interrupt
request occurs and the interrupt request bit is set to “1.”
The receive completion flag is cleared to “0” when the low-order of the UARTi receive buffer register is read
out.
The
____
RTSi
pin’s
output
level
becomes
“L”
simultaneously
with

(when
____
RTS
function
is
selected).
Figure
8.4.12 shows an example of receive timing when transfer data has a length of 8 bits.
Transmitter side
TxDi
RxDi
Receiver side
TxDi
RxDi
CTSi
RTSi (Note)
Note: The RTSi output function is not assigned for
Fig. 8.4.11 Connection example
7733 Group User’s Manual
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