M16C80 Datasheet, PDF (153/358 Pages) Renesas Technology Corp – RENESAS 16-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M16C/80 SERIES

M16C/80 Group
17. Clock synchronous serial I/O mode
(a) Polarity select function
As shown in Figure 17.3, the CLK polarity select bit (bit 6 at addresses 036416, 036C16, 033C16,
032C16, 02FC16) allows selection of the polarity of the transfer clock.
• When CLK polarity select 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 when not
transferring data is “H”.
• 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 when not
transferring data is “L”.
Figure 17.3 Polarity of transfer clock
(b) LSB first/MSB first select function
As shown in Figure 17.4, when the transfer format select bit (bit 7 at addresses 036416, 036C16,
033C16, 032C16, 02FC16) = “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
RXDi
D7 D6 D5 D4 D3 D2 D1 D0
D7 D6 D5 D4 D3 D2 D1 D0
MSB first
Note: This applies when the CLK polarity select bit = “0”.
Figure 17.4 Transfer format
Rev.1.00 Aug. 02, 2005 ^{Page 142} of 329
REJ09B0187-0100