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Chapter 16
Error flag
UAnPE
UAnFE
UAnOVE
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16.5.8 Reception errors
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
UAnSTR register and a reception error interrupt request signal (INTUAnRE) is
output when an error occurs.
It is possible to ascertain which error occurred during reception by reading the
contents of the UAnSTR register.
Clear the reception error flag by writing 0 to it after reading it.
Table 16-6
Reception error causes
Reception error
Cause
Parity error
Received parity bit does not match the setting
Framing error
Stop bit not detected
Overrun error
Reception of next data completed before data was read from
receive buffer
Note
Note that even in case of a parity or framing error, data is transferred from the
receive shift register to the receive data register UAnRX. Consequently the
data from UAnRX must be read. Otherwise an overrun error UAnSTR.UAnOVE
will occur at reception of the next data.
In case of an overrun error, the receive shift register data is not transferred to
UAnRX, thus the previous data is not overwritten.
16.5.9 Parity types and operations
Caution
When using the LIN function, fix the UAnPS1 and UAnPS0 bits of the
UAnCTL0 register to 00.
The parity bit is used to detect bit errors in the communication data. Normally
the same parity is used on the transmission side and the reception side.
In the case of even parity and odd parity, it is possible to detect odd-count bit
errors. In the case of 0 parity and no parity, errors cannot be detected.
(1)
Even parity
• During transmission
The number of bits whose value is "1" among the transmit data, including
the parity bit, is controlled so as to be an even number. The parity bit values
are as follows.
– Odd number of bits whose value is "1" among transmit data:1
– Even number of bits whose value is "1" among transmit data:0
• During reception
The number of bits whose value is "1" among the reception data, including
the parity bit, is counted, and if it is an odd number, a parity error is output.
Preliminary User's Manual U17566EE1V2UM00
Asynchronous Serial Interface (UARTA)
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