HD6433713 datasheet(194/324 Pages) RENESAS

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10.3.2 Data Transfer Format

Figure 10-2 shows the synchronous data transfer format. Data can be sent and received in lengths

of 8 bits or 16 bits. Data is sent and received starting from the least significant bit, in LSB-first

format. Transmit data is output from one falling edge of the serial clock until the next falling

edge. Receive data is latched at the rising edge of the serial clock.

Figure 10-2 Synchronous Data Transfer Format

10.3.3 Clock

Eight internal clock sources or an external clock may be selected as the serial clock. When an

internal clock is used, pin SCK1 is the clock output pin.

10.3.4 Data Transmit/Receive

Initializing SCI1

Before data is sent or received, first SCI1 must be initialized by software. This is done by

writing the desired transfer conditions in serial mode register 1 (SMR1).

Transmitting

A transmit operation is carried out as follows.

•

Set bit SO1 in port mode register 2 (PMR2) to 1, making pin P93/SO1 the SO1 output pin.

Also set bit SCK1 in PMR2 to 1, making pin P91/SCK1 the SCK1 I/O pin. If necessary, set

the SO1PMOS bit in PMR3 for NMOS open-drain output at pin SO1.

Bit 0

Bit 1

Bit 2

Bit 3

Bit n – 1

Bit n

SCK

SI input data

latch timing

LSB

MSB

n = 7: 8-bit transfer mode

n = 15: 16-bit transfer mode

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HD6433713 Datasheet(PDF) 194 Page - Renesas Technology Corp