3822_03 Datasheet, PDF (203/328 Pages) Renesas Technology Corp – 8-BIT SINGLE-CHIP MICROCOMPUTER

APPLICATION
2.5 Serial I/O
(4) Processing upon occurrence of an errors
sParity error, framing error, or summing error
If a parity error, a framing error, or a summing error occurs, the flag corresponding to each error in
the serial I/O status register is set to “1.” These flags cannot be cleared to “0” automatically, so set
them to “0” by software.
The parity error flag, framing error flag, and summing error flag is set to “0” by setting the receive
enable bit to “0” or writing dummy data into the serial I/O status register.
sOverrun error
An overrun error occurs when data is already input in the receive buffer register and yet all data is
input in the receive shift register.
If an overrun error occurs, the data of the receive shift register is not transferred and the data of the
receive buffer register is held. At this time, even if the data of the receive buffer register is read out,
the data of the receive shift register is not transferred.
Consequently, the data of the receive shift register becomes unreadable, so that the receive data
becomes invalid.
If an overrun error occurs, after set the overrun error flag of the serial I/O status register to “0”,
perform a receive operation again.
The overrun error flag is set to “0” by one of the following operations.
•Set the serial I/O enable bit to “0”
•Set the receive enable bit to “0”
•Write data (arbitrary) into the serial I/O status register
3822 GROUP USER’S MANUAL
2–137