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MB90560 series
CHAPTER 13 UART
355
G
Clock Selector
The clock selector selects the dedicated baud rate generator, external input clock, or internal
clock (clock supplied from the 16-bit reload timer) as the transmitting and receiving clocks.
G
Reception Control Circuit
The reception control circuit consists of a received bit counter, start bit detection circuit, and
received parity counter.The received bit counter counts receive data bits. When reception of one
data item for the specified data length is complete, the received bit counter generates a
reception interrupt request. The start bit detection circuit detects start bits from the serial input
signal. When the circuit detects a start bit, it writes data in the SIDR1 register by shifting at the
specified transfer rate. The received parity counter calculates the parity of the receive data.
G
Transmission Control Circuit
The transmission control circuit consists of a transmission bit counter, transmission start circuit,
and transmission parity counter.The transmission bit counter counts transmission data bits.
When transmission of one data item of the specified data length is complete, the transmission bit
counter generates a transmission interrupt request. The transmission start circuit starts
transmission when data is written to SODR0/1. The transmission parity counter generates a
parity bit for data to be transmitted when parity is enabled.
G
Reception Shift Register
The reception shift register fetches receive data input from the SIN pin, shifting the data bit by
bit. When reception is complete, the reception shift register transfers receive data to the SIDR0/1
register.
G
Transmission Shift Register
The transmission shift register transfers data written to the SODR0/1 register to itself and
outputs the data to the SOT pin, shifting the data bit by bit.
G
Serial Mode Control Register 1 (SMC0/1)
This register performs the following operations:
Selecting a UART operation mode
Selecting a clock input source
Setting up the dedicated baud rate generator
Selecting a clock rate (clock division value) when using the dedicated baud rate generator
Specifying whether to enable serial data output to the corresponding pin
Specifying whether to enable clock output to the corresponding pin