M30245 datasheet(49/367 Pages) RENESAS

49 / 367 page

Rev.2.00 Oct 16, 2006

page 40 of 354

REJ09B0340-0200

M30245 Group

2. Clock-Synchronous Serial I/O

_______ _______

The clock-synchronous serial I/O has three types of CTS/RTS functions to choose from:

_______ _______

• CTS/RTS functions disabled

_______ _______

CTS/RTS pin is a programmable I/O port.

_______

• CTS function only enabled

_______ _______

_______

CTS/RTS pin performs the CTS function.

_______

• RTS function only enabled

_______ _______

_______

CTS/RTS pin performs the RTS function.

(b) Function for choosing CLK polarity

This function switches the polarity of the transfer clock. The following operations are available:

• Data is input at the falling edge of the transfer clock, and is output at the rising edge.

• Data is input at the rising edge of the transfer clock, and is output at the falling edge.

This function is to choose whether to transmit/receive data from bit 0 or from bit 7. Choose either of

the following:

• LSB first

Data is transmitted/receivec from bit 0.

• MSB first

Data is transmitted/received from bit 7.

(d) Function for choosing continuous receive mode

Continuous receive mode is a mode in which reading the receive buffer register makes the reception-

enabled status ready. In this mode, there is no need to write dummy data to the transmit buffer

the receive buffer register into a dummy manner.

• Normal mode

Writing dummy data to the transmit buffer register makes the

reception enabled status ready.

• Continuous receive mode

Reading the reception buffer register makes the reception-enabled

status ready.

(e) Data logic select function

This function is to reverse data when writing to transmit buffer register or reading from receive buffer register.

(f) Function for choosing a transmission interrupt factor

The timing to generate a transmission interrupt can be selected from the following: the instant the

transmission buffer is emptied or the instant the transmission register is emptied. When transmis-

sion buffer empty timing is selected, an interrupt occurs when transmitted data is moved from the

transmission buffer to the transmission register. Therefore, data can be transmitted in succession.

When transmission register empty timing is selected, an interrupt occurs when data transmission is

complete.

(g) TxD, RxD I/O polarity reverse function

This function is to reverse a polarity of TxD port output level and a polarity of RxD port input level.

Following are some examples in which various functions (a) through (g) are selected:

_______

• Transmission Operation WITH: CTS function, transmission at falling edge of transfer clock, LSB

First, interrupt at instant transmission buffer is emptied

_______ _______

• Transmission Operation WITH: CTS/RTS function disabled, transmission at falling edge of transfer

clock, LSB First, interrupt at instant transmission is completed

________

• Reception Operation WITH: RTS function, reception at falling edge of transfer clock, LSB First, suc-

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