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Serial Interface
13-45
13.4.4 Description of Operation
■ UART Serial Interface connection
Two different connection methods are possible, one for unidirectional transfer, and the other for bi-directional
transfer.
The SBO pin is always an output, and the SBI pin is always an input.
Fig. 13-4-2 Connections
■ UART serial interface bit rate
The UART serial interface has an internal 7-bit dedicated counter that supports fast bit rates even with a comparatively
slow clock source.
For example, when IOCLK is being used and a transfer is being performed, the division ratio should be set as
follows:
Note: When an external clock signal is used as the clock source, the high and low widths of the external clock must
be at least 10, 5, or 2.5 SYSCLK cycles when (MCLK frequency/SYSCLK frequency) = 1, 2, or 4, respectively.
SBO
SBI
SBT
SBO
SBI
SBT
SBO
SBI
SBO
SBI
SBT SBT
ReceptionTransmission
Transmission/
reception
Transmission/
reception
External
clock
External
clock
Unidirectional transfer Bi-directional transfer