Reception Errors; Parity Types And Operations - NEC V850ES/F 3-L Series User Manual

Chapter 15
Note

15.5.9 Reception errors

Table 15-2
Error flag Reception error
UDnPE Parity error
Framing error
UDnFE
UDnOVE Overrun error
Note

15.5.10 Parity types and operations

Caution
416
and the UDnPWR bit = 0 or UDnRXE bit = 0 conflict, the INTUDnR signal
may be generated in spite of these being no data stored in the UDnRX
register.
To complete reception without waiting INTUDnR signal generation, be sure
to clear (0) the interrupt request flag (UDnRIF) of the UDnRIC register, after
setting (1) the interrupt mask flag (UDnRMK) of the interrupt control register
(UDnRIC) and then set (1) the UDnPWR bit = 0 or UDnRXE bit = 0.
1. If the low level is always input to the RXDDn pin, it is not judged as the start
bit.
2. In continuous reception, immediately after the stop bit is detected at the
first reception bit (when the reception completion interrupt is generated),
the next start bit can be detected.
3. If the UDnRDL = 1 (receive data inversion input) is selected, when the
reception is started, change the data reception pin to the UART receive pin
mode and then enable the reception. If the pin mode is changed after the
reception is enabled, the start bit is detected faultily if the pin level at this
time is high level.
Errors during a receive operation are of three types: parity errors, framing
errors, and overrun errors. Data reception result error flags are set in the
UDnSTR register and a status interrupt request signal INTUDnS is output
when an error occurs.
It is possible to ascertain which error occurred during reception by reading the
contents of the UDnSTR register.
Clear the reception error flag by writing 0 to it after reading it.
Reception error causes
Cause
Received parity bit does not match the setting
Stop bit not detected
Reception of next data completed before data was read from
receive buffer
Note that even in case of a parity or framing error, data is transferred from the
receive shift register to the receive data register UDnRX. Consequently the
data from UDnRX must be read. Otherwise an overrun error
UDnSTR.UDnOVE will occur at reception of the next data.
In case of an overrun error, the receive shift register data is not transferred to
UDnRX, thus the previous data is not overwritten.
When using the LIN function, fix the UDnPS1 and UDnPS0 bits of the
UDnCTL0 register to 00.
User's Manual U18743EE1V2UM00
Asynchronous Serial Interface (UARTD)