Polarity Select Function; Lsb First/Msb First Select Function - Renesas R8C Series User Manual

R8C/1A Group, R8C/1B Group
15.1.1

Polarity Select Function

Figure 15.8 shows the Transfer Clock Polarity. Use the CKPOL bit in the U0C0 register to select the transfer
clock polarity.
• When the CKPOL bit in the U0C0 register = 0 (output transmit data at the falling
edge and input the receive data at the rising edge of the transfer clock)
CLK0
TXD0
RXD0
• When the CKPOL bit in the U0C0 register = 1 (output transmit data at the rising
edge and input receive data at the falling edge of the transfer clock)
CLK0
TXD0
RXD0
NOTES :
1. When not transferring, the CLK0 pin level is "H".
2. When not transferring, the CLK0 pin level is "L".
Figure 15.8 Transfer Clock Polarity
15.1.2

LSB First/MSB First Select Function

Figure 15.9 shows the Transfer Format. Use the UFORM bit in the U0C0 register to select the transfer format.
• When UFORM bit in U0C0 register = 0 (LSB first)
CLK0
TXD0
RXD0
• When UFORM bit in U0C0 register = 1 (MSB first)
CLK0
TXD0
RXD0
NOTE :
1. The above applies when the CKPOL bit in the U0C0 register is
Figure 15.9 Transfer Format
Rev.1.30 Dec 08, 2006
REJ09B0252-0130
(1)
D0 D1
D0 D1
(2)
D0 D1
D0 D1
D0 D1 D2
D0 D1 D2
D7 D6 D5
D7 D6 D5
set to 0 (output transmit data at the falling edge and input receive
data at the rising edge of the transfer clock).
Page 161 of 315
D2 D3 D4 D5
D2 D3 D4 D5
D2 D3 D4 D5
D2 D3 D4 D5
(1)
D3 D4 D5
D3 D4 D5
(1)
D4 D3 D2
D4 D3 D2
15. Serial Interface
D6 D7
D6 D7
D6 D7
D6 D7
D6 D7
D6 D7
D1 D0
D1 D0