NEC 78K0 User Manual page 255

(e) Reception error
Three types of errors may occur during reception: a parity error, framing error, or overrun error. If the error
flag of asynchronous serial interface reception error status register 0 (ASIS0) is set as a result of data
reception, a reception error interrupt request (INTSR0) is generated.
Which error has occurred during reception can be identified by reading the contents of ASIS0 in the reception
error interrupt servicing (INTSR0) (refer to Figure 12-3).
The contents of ASIS0 are reset to 0 when ASIS0 is read.
Reception Error
Parity error
Framing error
Overrun error
(f) Noise filter of receive data
The R D0 signal is sampled using the base clock output by the prescaler block.
X
If two sampled values are the same, the output of the match detector changes, and the data is sampled as
input data.
Because the circuit is configured as shown in Figure 12-10, the internal processing of the reception operation
is delayed by two clocks from the external signal status.
Base clock
R D0/SI10/P11
X
CHAPTER 12 SERIAL INTERFACE UART0
Table 12-3. Cause of Reception Error
The parity specified for transmission does not match the parity of the
receive data.
Stop bit is not detected.
Reception of the next data is completed before data is read from
receive buffer register 0 (RXB0).
Figure 12-10. Noise Filter Circuit
Internal signal A
In Q
Match detector
User's Manual U16227EJ2V0UD
Cause
In Q
LD_EN
Internal signal B
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