M16C User Manual.pdf

Clock-Synchronous Serial I/OMitsubishi microcomputersM16C / 62 GroupSINGLE-CHIP 16-BIT CMOS MICROCOMPUTER_______ _______• CTS/RTS functions disabled_______• CTS function only enabled_______• RTS function only enabled_______ _______• CTS/RTS separation function_______ _______CTS/RTS pin is a programmable I/O port._______ ______________CTS/RTS pin performs the CTS function._______ ______________CTS/RTS pin performs the RTS function.______________P60 pin works the RTS function, and P64 pin performs the CTS_______ ______________function. When CTS/RTS separation function is selected, CTS/_______RTS function cannot select simultaneously.(b) Function for choosing polarityThis 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.(c) Function for choosing which bit to transmit firstThis function is to choose whether to transmit data from bit 0 or from bit 7. Choose either of thefollowing:• LSB first Data is transmitted from bit 0.• MSB first Data is transmitted from bit 7.(d) Function for choosing successive reception modeSuccessive reception mode is a mode in which reading the receive buffer register makes the reception-enabledstatus ready. In this mode, there is no need to write dummy data to the transmit bufferregister so as to make the reception-enabled status ready. But at the time of starting reception, readthe receive buffer register into a dummy manner.• Normal modeWriting dummy data to the transmit buffer register makes thereception enabled status ready.• Successive reception mode Reading the reception buffer register makes the reception-enabledstatus ready.(e) Function for outputting transfer clock to multiple pinsThis function is to switch among pins to output the transfer clock. This function is effective only whenselecting the internal clock. Switching among pins for outputting the transfer clock allows data transmissionto two external ICs in a time-sharing manner.(f) Data logic select functionThis function is to reserve data when writing to transmit buffer register or reading from receive buffer register.(g) Function for choosing a transmission interrupt factorThe timing to generate a transmission interrupt can be selected from the following: the instant thetransmission buffer is emptied or the instant the transmission register is emptied. When transmissionbuffer empty timing is selected, an interrupt occurs when transmitted data is moved from thetransmission 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 iscomplete.(h) TxD, RxD I/O polarity reverse functionThis function is to reserve a polarity of TxD port output level and a polarity of RxD port input level.327