M16C6K9 Datasheet, PDF (111/292 Pages) Renesas Technology Corp – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

M16C/6K9 Group
Serial I/O
Clock synchronous serial I/O mode
(a) Polarity selection function
As shown in Fig.GA-11, the CLK polarity selection bit (bit 6 at addresses 03A416, 03AC16, 037C16) allows to
select the polarity of the transfer clock.
• When CLK polarity selection bit = “0”
CLKi
TXDi
D0 D1 D2 D3 D4 D5 D6 D7
RXDi
D0 D1 D2 D3 D4 D5 D6 D7
Note 1: The CLK pin level is "H" when
there is no transferring.
• When CLK polarity select bit = “1”
CLKi
TXDi
D0 D1 D2 D3 D4 D5 D6 D7
RXDi
D0 D1 D2 D3 D4 D5 D6 D7
Note 2: The CLK pin level is "L" when
there is no transferring.
Fig.GA-11 Polarity of transfer clock
(b) LSB first/MSB first selection function
As shown in Fig.GA-12, when the transfer format selection bit (bit 7 at addresses 03A416, 03AC16, 037C16)
= “0”, the transfer format is “LSB first”; when the bit = “1”, the transfer format is “MSB first”.
• When transfer format selection 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 selection bit = “1”
CLKi
TXDi
D7 D6 D5 D4 D3 D2 D1 D0
RXDi
D7 D6 D5 D4 D3 D2 D1 D0
MSB first
Note: This applies when the CLK polarity selection bit = “0”.
Fig.GA-12 Transfer format
Rev.1.00 Jun 06, 2003 page 111 of 290