M16C User Manual.pdf

Clock-Synchronous Serial I/OMitsubishi microcomputersM16C / 62 GroupSINGLE-CHIP 16-BIT CMOS MICROCOMPUTERTransmission(1) With an external clock selected, perform the following set-up procedure with the CLKi pininput level = “H” if the CLK polarity select bit = “0” or with the CLKi pin input level = “L” if theCLK polarity select bit = “1”:1. Set the transmit enable bit (to “1”)2. Write transmission data to the UARTi transmit buffer register_______________3. “L” level input to the CTSi pin (when the CTS function is selected)Reception(1) In operating the clock-synchronous serial I/O, operating a transmitter generates a shift clock.Fix settings for transmission even when using the device only for reception. Dummy data isoutput to the outside from the TxDi pin (transmission pin) when receiving data.(2) With the internal clock selected, setting the transmit enable bit to “1” (transmission-enabledstatus) and setting dummy data in the UARTi transmission buffer register generates a shiftclock.With the external clock selected, a shift clock is generated when the transmit enable bit is setto “1”, dummy data is set in the UARTi transmit buffer register, and the external clock is inputto the CLKi pin.(3) In receiving data in succession, an overrun error occurs when the next reception data is madeready in the UARTi receive register with the receive complete flag set to “1” (before thecontent of the UARTi receive buffer register is read), and overrun error flag is set to “1”. In thisinstance, the next data is written to the UARTi receive buffer register, so handle with thisproblem by writing programs on transmission side and reception side so that the previousdata is transmitted again.If an overrun error occurs, the UARTi receive interrupt request bit does not go to “1”.(4) To receive data in succession, set dummy data in the lower-order byte of the UARTi transmitbuffer register every time reception is made.(5) With an external clock selected, perform the following set-up procedure with the CLKi pininput level = “H” if the CLK polarity select bit = “0” or with the CLKi pin input level = “L” if theCLK polarity select bit = “1”:1. Set receive enable bit (to “1”)2. Set transmit enable bit (to “1”)3. Write dummy data to the UARTi transmit buffer register_______(6) Output from the RTS pin goes to “L” level as soon as the receive enable bit is set to “1”. Thisis not related to the content of the transmit buffer empty flag or the content of the transmitenable bit._______Output from the RTS pin goes to “H” level when reception starts, and goes to “L” level whenreception is completed. This is not related to the content of the transmit buffer empty flag orthe content of the receive complete flag.347