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Rev. 1.21
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HT66F488/HT66F489
A/D Flash MCU with EEPROM
HT66F488/HT66F489
A/D Flash MCU with EEPROM
UART Module Serial Interface
The device contains an integrated full-duplex asynchronous serial communications UART interface
that enables communication with external devices that contain a serial interface. The UART function
has many features and can transmit and receive data serially by transferring a frame of data with
eight or nine data bits per transmission as well as being able to detect errors when the data is
overwritten or incorrectly framed. The UART function possesses its own internal interrupt which
can be used to indicate when a reception occurs or when a transmission terminates.
The integrated UART function contains the following features:
• Full-duplex, Universal Asynchronous Receiver and Transmitter (UART) communication
• 8 or 9 bits character length
• Even, odd or no parity options
• One or two stop bits
• Baud rate generator with 8-bit prescaler
• Parity, framing, noise and overrun error detection
• Support for interrupt on address detect (last character bit=1)
• Transmitter and receiver enabled independently
• 2-byte Deep FIFO Receive Data Buffer
• Transmit and receive interrupts
• Transmit and Receive Multiple Interrupt Generation Sources:
♦
Transmitter Empty
♦
Transmitter Idle
♦
Receiver Full
♦
Receiver Overrun
♦
Address Mode Detect
♦
RX pin Wake-up
UART External Interface
To communicate with an external serial interface, the internal UART has two external pins known
as TX and RX. The TX pin is the UART transmitter pin, which can be used as a general purpose I/O
or other pin-shared functional pin if the pin is not configured as a UART transmitter, which occurs
when the TXEN bit in the UCR2 control register is equal to zero. Similarly, the RX pin is the UART
receiver pin, which can also be used as a general purpose I/O or other pin-shared functional pin, if
the pin is not configured as a receiver, which occurs if the RXEN bit in the UCR2 register is equal to
zero. Along with the UARTEN bit, the TXEN and RXEN bits, if set, will automatically setup these
I/O or other pin-shared functional pins to their respective TX output and RX input conditions and
disable any pull-high resistor option which may exist on the RX pin.