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7733 Datasheet, PDF (245/940 Pages) Renesas Technology Corp – 16-BIT SINGLE-CHIP MICROCOMPUTER | |||
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SERIAL I/O
8.3 Clock synchronous serial I/O mode
8.3.7 Processing when an overrun error is detected
In the clock synchronous serial I/O mode, an overrun error can be detected.
An overrun error occurs when the next data is prepared in the UARTi receive register with the receive
completion flag = â1â (in other words, data is present in the UARTi receive buffer register), and then the
next data is transferred to the receive buffer register. In other words, when the next data is prepared before
the contents of the UARTi receive buffer register is read out, an overrun error occurs. When an overrun
error occurs, the next data is written into the UARTi receive buffer register. At this time, the UARTi receive
interrupt request bit does not change.
An overrun error is detected when data is transferred from the UARTi receive register to the UARTi receive
buffer register. At this time, the overrun error flag is set to â1.â The overrun error flag is cleared to â0â when
the serial I/O mode selection bits are cleared to â0002â or when the receive enable bit is cleared to â0.â
When an overrun error occurs during reception, initialize the overrun error flag and the UARTi receive
buffer register, and then perform reception again. When it is necessary to perform transmission owing to
an overrun error which occurs in the receiver side, set the UARTi transmission buffer register again, and
then starts transmission again.
The method of initializing the UARTi receive buffer register and that of setting the UARTi transmission
buffer register again are described below.
(1) Method of Initializing UARTi receive buffer register
 Clear the receive enable bit to â0.â (Reception is disabled.)
 Set the receive enable bit to â1â again. (Reception is enabled.)
(2) Method of setting UARTi transmission buffer register again
 Clear the serial I/O mode selection bits to â0002.â (Serial I/O is ignored.)
 Set the serial I/O mode selection bits to â0012â again.
 Set the transmit enable bit to â1.â (Transmission is enabled.) And set the transmit data to the UARTi
transmission buffer register.
8â42
7733 Group Userâs Manual
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