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M38B71M1 Datasheet(PDF) 35 Page - Renesas Technology Corp |
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M38B71M1 Datasheet(HTML) 35 Page - Renesas Technology Corp |
35 / 110 page ![]() 38B7 Group SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER MITSUBISHI MICROCOMPUTERS 34 When the internal synchronous clock is selected, in the 8-bit serial I/O mode and the automatic transfer serial I/O mode (SBUSY1 out- put function outputs in 1-byte units), the SBUSY1 output goes to “L” and the SBUSY1 output goes to “H” before 0.5 cycle (transfer clock) of the timing at which the transfer clock from the SCLK1 output goes to “L” at a start of transmit/receive operation. In the automatic transfer serial I/O mode (the SBUSY1 output func- tion outputs all transfer data), the SBUSY1 output goes to “L” and the SBUSY1 output goes to “H” when the first transmit data is writ- ten into the serial I/O1 register (address 001B16). When the external synchronous clock is selected, the SBUSY1 out- put goes to “L” and the SBUSY1 output goes to “H” when transmit data is written into the serial I/O1 register to start a transmit opera- tion, regardless of the serial I/O transfer mode. At termination of transmit/receive operation, the SBUSY1 output re- turns to “H” and the SBUSY1 output returns to “L”, the initial status, when the serial transfer status flag is set to “0”, regardless of whether the internal or external synchronous clock is selected. Furthermore, in the automatic transfer serial I/O mode (SBUSY1 output function outputs in 1-byte units), the SBUSY1 output goes to “H” and the SBUSY1 output goes to “L” each time 1-byte of receive data is written into the automatic transfer RAM. Fig. 29 SBUSY1 output operation (internal synchronous clock, 8-bit serial I/O) Fig. 30 SBUSY1 output operation (external synchronous clock, 8-bit serial I/O) Fig. 31 SBUSY1 output operation in automatic transfer serial I/O mode (internal synchronous clock, SBUSY1 output function outputs each 1-byte) SBUSY1 SCLK1 SOUT1 Serial transfer status flag Serial transfer status flag SBUSY1 SCLK1 Write to Serial I/O1 register SCLK1 SBUSY1 SOUT1 Automatic transfer interval Serial transfer status flag Automatic transfer RAM →Serial I/O1 register Serial I/O1 register →Automatic transfer RAM |