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12
• About overrun error
If all bits of the next receive data are received in the SIO Receive Shift Register before you read out
the SIO Receive Buffer Register (an overrun error occurs), the receive data is not stored in the
Receive Buffer Register and the Receive Buffer Register retains the previously received data.
Thereafter, although receive operation is continued, no receive data is stored in the Receive Buffer
Register (the receive status bit = 1). To restart reception normally, you need to temporarily clear the
receive enable bit before you restart. This is the only way you can clear the overrun error flag.
• About DMA transfer request generation during SIO transmission
If the Transmit Buffer Register becomes empty (the transmit buffer empty flag = 1) while the
transmit enable bit is set to 1 (transmit enabled), an SIO transmit buffer empty DMA transfer
request is generated.
• About DMA transfer request generation during SIO reception
When the receive-finished bit is set to 1 (the receive buffer register full), a receive-finished DMA
transfer request is generated. However, if an overrun error has occurred, this DMA transfer request
is not generated.
12.5 Precautions on Using CSIO Mode
12-44
SERIAL I/O
Ver.0.10
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