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M30245 Group
Clock synchronous serial I/O mode
Rev.2.00
Oct 16, 2006
page 132 of 264
REJ03B0005-0200
Clock synchronous serial I/O mode
The clock synchronous serial I/O mode uses a transfer clock to transmit and receive data. Table 1.44 list the specifica-
tions of the clock synchronous serial I/O mode.
Table 1.44. Clock synchronous serial I/O mode specifications
Note 1: "m" denotes the value 0016 to FF16 that is set in the UART bit rate generator.
Note 2: If an overrun error occurs, the value of the UiRB register will be indeterminate. The IR bit of
the SiRIC register does not change.
Item
Specification
Transfer data format
Transfer data length: 8-bits
Transfer clock
When internal clock is selected (bit 3 at address 03A816, 036816, 033816, 032816 ="0"):
fi/2(m+1) (Note 1)
fi = f1, f8, f32
When external clock is selected (bit 3 at 03A816, 036816, 033816, 032816 = "1"):
Input from CLKi pin
Transmission/reception control
CTS function/RTS function/CTS, RTS function not used
Transmission start condition
To start transfer, the following criteria must be met:
-Transmit enable bit (bit 0 at 03AD16, 036D16, 033D16, 032D16) = "1"
-Transmit buffer empty flag (bit 1 at 03AD 16, 036D16, 033D16, 032D16) = "0"
-When CTS function selected, CTS input level = "L"
Furthermore, if external clock is selected, the following requirements must also be met:
-CLKi polarity select bit (bit 6 at 03AC16, 036C16, 033C16, 032C16)= "0": CLKi input level = "H"
-CLKi polarity select bit (bit 6 at 03AC16, 036C16, 033C16, 032C16)= "1": CLKi input level = "L"
Receive start condition
To start reception, the following requirement must be met:
-Receive enable bit (bit 2 at 03AD16, 036D16, 033D16, 032D16) = "1"
-Transmit enable bit (bit 0 at 03AD16, 036D16, 033D16, 032D16) = "1"
-Transmit buffer empty flag (bit 1 at 03AD 16, 036D16, 033D16, 032D16) = "0"
Furthermore, if external clock is selected, the following requirement must be met:
-CLKi polarity select bit (bit 6 at 03AC16, 036C16, 033C16, 032C16)= "0": CLKi input level = "H"
-CLKi polarity select bit (bit 6 at 03AC16, 036C16, 033C16, 032C16)= "1": CLKi input level = "L"
Interrupt request generation
timing
When transmitting:
-Transmit interrupt cause select bit (bit 4 at 3AD16, 036D16, 033D16, 032D16) = "0": Interrupt requested
when data transfer from UARTi transfer buffer register to UARTi transmit register is complete
-Transmit interrupt cause select bit (bit 4 at 3AD16, 036D16, 033D16, 032D16) = "1": Interrupt requested
when data transmission from UARTi transmit register is complete
When receiving:
-Interrupt requested when data transfer from UARTi receive register to UARTi receive buffer register is
completed.
Error detection
Overrun error (Note 2)
This error occurs if the serial I/O starts receiving the next data and receives the 7th bit of the next
data before reading the UiRB register.
Select function
CLK polarity selection
Whether transmit data is output/input at the rising edge or falling edge or the transfer clock can be
selected
LSB first/MSB first selection
Whether transmission/reception begins with bit 0 or bit 7 can be selected
Continuous receive mode selection
Reception is enabled simultaneously by a read form the receive buffer register
Switching serial data log
Reverse data when writing to the transmission buffer register or reading the reception buffer register
can selected
TxD, RxD, I/O polarity reverse
This function reverses the TxD port output and RxD port input. All I/O data level is reversed.