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Serial I/O
12.3 Transmit Operation in CSIO Mode
32180 Group User's Manual (Rev.1.0)
12.3.2 Initializing CSIO Transmission
To transmit data in CSIO mode, initialize the serial I/O following the procedure described below.
(1) Setting SIO Transmit/Receive Mode Register
• Set the register to CSIO mode.
• Select the internal or an external clock.
(2) Setting SIO Transmit Control Register
• Select the clock divider’s divide-by ratio (when internal clock selected).
(3) Setting SIO Baud Rate Register
When the internal clock is selected, set a baud rate generator value. (See Section 12.3.1, “Setting the CSIO
Baud Rate.”)
(4) Setting the 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 transmit interrupt requests (SIO Interrupt Request Enable Register).
Note: • Transmission finished interrupt requests are effective only when the internal clock is selected.
(5) Setting the Interrupt Controller (SIO Transmit Interrupt Control Register)
To use transmit interrupts, set their priority levels.
(6) Setting the 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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