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SERIAL I/O
7.4 Clock asynchronous serial I/O (UART) mode
7.4.3 Method of transmission
Figure 7.4.3 shows an initial setting example for relevant registers when transmitting.
The difference due to selection of transfer data length (7 bits, 8 bits, or 9 bits) is only that data length.
When selecting a 7- or 8-bit data length, set the transmit data into the low-order byte of the UARTi transmit
buffer register. When selecting a 9-bit data length, set the transmit data into that low-order byte and bit
0 of that high-order byte.
Transmission is started when all of the following conditions (
Transmit is enabled (transmit enable bit = "1").
Transmit data is present in the UARTi transmit buffer register (transmit buffer empty flag = "0").
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CTS
pin's input is "L" level (when CTS function selected).
i
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Note: When the CTS function is not selected, this condition is ignored.
When using interrupts, it is necessary to set the corresponding register to enable interrupts. For details,
refer to "Chapter 4. INTERRUPTS."
Figure 7.4.4 shows writing data after start of transmission, and Figure 7.4.5 shows detection of transmission's
completion.
7–40
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7751 Group User's Manual
to
) are satisfied:
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