7721 datasheet(225/577 Pages) RENESAS

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SERIAL I/O

7721 Group User’s Manual

11–22

11.3 Clock synchronous serial I/O mode

D0 D1 D2 D3

D4 D5 D6 D7 D0 D1 D2 D3 D4

D0 D1 D2 D3 D4 D5 D6 D7

TCLK

CLKi

TENDi

TxDi

Transfer clock

Transmit enable bit

Transmit buffer

empty flag

Transmit register

empty flag

UARTi transmit

interrupt request bit

Data is set in UARTi transmit buffer register.

UARTi transmit register

UARTi transmit buffer register.

Stopped because transmit enable bit = “0.”

TENDi: Next transmit conditions are examined when this signal level is “H.”

ENDi

is an internal signal. Accordingly, it cannot be read from the external.)

Tc = TCLK = 2(n+1) /fi

, f16, f64, f512)

Cleared to “0” when interrupt request is accepted or cleared by software.

The above timing diagram applies

when the following conditions are

satisfied:

q Internal clock selected

q CTS function not selected

D0 D1

D2 D3 D4 D5

D6 D7

D0 D1

D2 D3 D4 D5

D6 D7

D0 D1 D2 D3

D4 D5 D6

CTSi

CLKi

TENDi

TxDi

Transfer clock

Transmit enable bit

Transmit buffer

empty flag

Transmit register

empty flag

UARTi transmit

interrupt request bit

TCLK

Data is set in UARTi transmit buffer register.

UARTi transmit register

UARTi transmit buffer register.

Stopped because CTSi = “H.”

Stopped because transmit enable bit = “0.”

TENDi: Next transmit conditions are examined when this signal level is “H.”

ENDi

is an internal signal. Accordingly, it cannot be read from the external.)

Tc = TCLK = 2(n+1) /fi

, f16, f64, f512)

Cleared to “0” when interrupt request is accepted or cleared by software.

The above timing diagram applies when

the following conditions are satisfied:

q Internal clock selected

q CTS function selected

____

Fig. 11.3.5 Example of transmit timing (when selecting internal clock, selecting CTS function)

____

Fig. 11.3.6 Example of transmit timing (when selecting internal clock, not selecting CTS function)

fi: BRGi count source frequency (f

n: Value set in BRGi

fi: BRGi count source frequency (f

n: Value set in BRGi

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