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Serial I/O
12.6 Transmit Operation in UART Mode
32180 Group User's Manual (Rev.1.0)
12.6.3 Initializing UART Transmission
To transmit data in UART mode, initialize the serial I/O following the procedure described below.
(1) Setting SIO Transmit/Receive Mode Register
• Set the register to UART mode.
• Set parity (when enabled, select odd/even).
• Set the stop bit length.
• Set the character length (Note 1).
Note 1: During UART mode, settings of the internal/external clock select bit have no effect (only the
internal clock is useful).
(2) Setting SIO Transmit Control Register
• Select the clock divider’s divide-by ratio.
(3) Setting SIO Baud Rate Register
Set a baud rate generator value. (See Section 12.6.1, “Setting the UART Baud Rate.”)
(4) Setting SIO interrupt related registers
• Select the source of transmit interrupt request (transmit buffer empty or transmission finished)
(SIO Interrupt Request Source Select Register).
• Enable or disable SIO transmit interrupt requests (SIO Interrupt Request Enable Register).
(5) Setting Interrupt Controller (SIO Transmit Interrupt Control Register)
To use transmit interrupts, set their priority levels.
(6) Setting DMAC
To issue DMA transfer requests to the internal DMAC when the transmit buffer is empty, set up the DMAC.
(See Chapter 9, “DMAC.”)
(7) Selecting pin functions
Because the serial I/O related pins serve dual purposes, set the pin functions for use as SIO pins or input/
output ports. (See Chapter 8, “Input/Output Ports and Pin Functions.”)
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