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Rev. 2.50
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Rev. 2.50
253
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HT66F20/HT66F30/HT66F40/HT66F50/HT66F60
HT66FU30/HT66FU40/HT66FU50/HT66FU60
A/D Flash MCU with EEPROM
HT66F20/HT66F30/HT66F40/HT66F50/HT66F60
HT66FU30/HT66FU40/HT66FU50/HT66FU60
A/D Flash MCU with EEPROM
• Receiving break
Any break character received by the UART will be managed as a framing error. The receiver
will count and expect a certain number of bit times as specified by the values programmed into
the BNO and STOPS bits. If the break is much longer than 13 bit times, the reception will be
considered as complete after the number of bit times specified by BNO and STOPS. The RXIF
bit is set, FERR is set, zeros are loaded into the receive data register, interrupts are generated if
appropriate and the RIDLE bit is set. If a long break signal has been detected and the receiver has
received a start bit, the data bits and the invalid stop bit, which sets the FERR flag, the receiver
must wait for a valid stop bit before looking for the next start bit. The receiver will not make
the assumption that the break condition on the line is the next start bit. A break is regarded as
a character that contains only zeros with the FERR flag set. The break character will be loaded
into the buffer and no further data will be received until stop bits are received. It should be noted
that the RIDLE read only flag will go high when the stop bits have not yet been received. The
reception of a break character on the UART registers will result in the following:
♦
The framing error flag, FERR, will be set.
♦
The receive data register, RXR, will be cleared.
♦
The OERR, NF, PERR, RIDLE or RXIF flags will possibly be set.
• Idle status
When the receiver is reading data, which means it will be in between the detection of a start bit
and the reading of a stop bit, the receiver status flag in the USR register, otherwise known as the
RIDLE flag, will have a zero value. In between the reception of a stop bit and the detection of
the next start bit, the RIDLE flag will have a high value, which indicates the receiver is in an idle
condition.
• Receiver interrupt
The read only receive interrupt flag RXIF in the USR register is set by an edge generated by
the receiver. An interrupt is generated if RIE=1, when a word is transferred from the Receive
Shift Register, RSR, to the Receive Data Register, RXR. An overrun error can also generate an
interrupt if RIE=1.