7477 datasheet(111/354 Pages) RENESAS

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HARDWARE

1-94

7470/7471/7477/7478 GROUP USER’S MANUAL

1.13 Serial I/O

[Transmit setting method]

1Clear the Serial I/O interrupt enable bit (bit 6 of the Interrupt control register 1) to “0.”

2Set the Serial I/O mode register according to “Table 1.13A.1.”

3When using the Serial I/O interrupt,

[1] Clear the Serial I/O interrupt request bit (bit 6 of the Interrupt request register 1) to “0.”

[2] Set the Serial I/O interrupt enable bit to “1.”

4Write transmit data into the Serial I/O register (address 00DD16).

Note: When the external clock is selected, perform a write operation while the synchronous clock is

at “H.”

Table 1.13A.1 shows a Serial I/O transmit setting.

Table 1.13A.1 Serial I/O transmit setting

Serial I/O mode register

(SM: Address 00DC16)

Bit

Setting value

Serial I/O port using

Serial I/O

Byte specification mode selection

____________________

P15/SOUT, SRDY pin output

format

(Note 3)

External clock

Internal clock

Serial I/O port (SOUT, CLK) (Note 2)

Ordinary port

_______________

SRDY

signal output

_______________

SRDY

signal

SARDY signal

Ordinary mode

Byte specification mode

CMOS output

N channel open drain output

Item

Synchronous clock selection

____________________

SRDY

signal output selection

____________________

SRDY

signal selection

Synchronous clock (at internal

clock selection)

(Note 1)

Notes 1: Select the internal clock as a synchronous clock in the following condition. In the 7470 group,

however, f(XCIN) is not available.

q When a divided signal of f(XIN) is selected, the system clock is f(XIN).

q When a divided signal of f(XCIN) is selected, the system clock is f(XCIN).

Select a system clock state by bit 7 of the CPU mode register.

2: When the ordinary port is switched over to the Serial I/O port, the Serial I/O interrupt request bit

may be set to “1.” Clear the Serial I/O interrupt request bit to “0” after one instruction or more

after switching the ordinary port over to the Serial I/O port.

3: When ordinary P17 is selected by bit 4 of the Serial I/O mode register, the CMOS output is

provided regardless of the set value of bit 7.

f(XIN)/8

f(XCIN)/8

f(XIN)/16

f(XCIN)/16

f(XIN)/32

f(XCIN)/32

f(XIN)/512

f(XCIN)/512

b1 • b0

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