HD404618TF datasheet(55/91 Pages) RENESAS

55 / 91 page

HD404618 Series

Serial Data Register (SRL: $006, SRU: $007): Eight-bit read/write register separated into upper and

lower digits located at sequential addresses.

Data in this register is output from the SO pin, LSB first, in synchronism with the falling edge of the

transmit clock, and data is input LSB first through the SI pin at the rising edge of the transmit clock.

Input/output timing is shown in figure 32.

Data cannot be read or written during serial data transmission. If a read/write occurs during transmission,

the accuracy of the resultant data cannot be guaranteed.

LSB

MSB

Transmit

clock

Serial

output

data

Serial input

data

latch timing

Figure 32 Serial Interface Timing

Selecting and Changing Operating Mode: Table 26 lists the serial interface operating modes. To select

an operating mode, use one of these combinations of PMR and SMR settings; to change the operating

mode, always initialize the serial interface internally by writing to the SMR.

Table 26 Serial Interface Operating Modes

SMR

PMRA

Bit 3

Bit 1

Bit 0

Operating Mode

Continuous clock output mode

Transmit mode

Receive mode

Transmit/receive mode

Serial Interface Operation: Three operating modes are provided for the serial interface; transitions

between them are shown in figure 33.

In STS waiting state, the serial interface is initialized and the transmit clock is ignored. If the STS

instruction is then executed, the serial interface enters transmit clock wait state.

In transmit clock wait state, input of the transmit clock increments the octal counter, shifts the serial clock

clock is continuously output but data is not transmitted.

HD404618TF Datasheet(PDF) 55 Page - Renesas Technology Corp