M16C1N Datasheet, PDF (128/238 Pages) Renesas Technology Corp – RENESAS 16-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M16C/10 SERIES

M16C/1N Group
13. Serial I/O
13.1.1 Polarity Select Function
As shown in Figure 13.8, the CLK polarity select bit (bit 6 at addresses 00A416 and 00AC16) allows
selection of the polarity of the transfer clock.
When CLK polarity select bit = "0"
CLKi
TXDi
RXDi
D0 D1 D2 D3 D4 D5 D6 D7
D0 D1 D2 D3 D4 D5 D6 D7
Note 1: The CLKi pin level when not
transferring data is "H".
When CLK polarity select bit = "1"
CLKi
TXDi
RXDi
D0 D1 D2 D3 D4 D5 D6 D7
D0 D1 D2 D3 D4 D5 D6 D7
Note 2: The CLKi pin level when not
transferring data is "L".
Figure 13.8 Polarity of transfer clock
13.1.2 LSB First/MSB First Select Function
As shown in Figure 13.9, when the transfer format select bit (bit 7 at addresses 00A416 and 00AC16)
= "0", the transfer format is "LSB first"; when the bit = "1", the transfer format is "MSB first".
When transfer format select bit = "0"
CLKi
TXDi
D0 D1 D2 D3 D4 D5 D6 D7
RXDi
D0 D1 D2 D3 D4 D5 D6 D7
LSB first
When transfer format select bit = "1"
CLKi
TXDi
D7 D6 D5 D4 D3 D2 D1 D0
RXDi
D7 D6 D5 D4 D3 D2 D1 D0
MSB first
Figure 13.9 Transfer format
Note 1: This applies when the CLK polarity select bit = "0".
Rev.1.00 Oct 20, 2004 page 116 of 222
REJ09B0007-0100Z