NEC 78K0/KD1 Series User Manual page 322

(4) Timing of output to SO10 pin (first bit)
When communication is started, the value of transmit buffer register 10 (SOTB10) is output from the SO10 pin.
The output operation of the first bit at this time is described below.
Writing to SOTB10 or
reading from SIO10
Output latch
The first bit is directly latched by the SOTB10 register to the output latch at the falling (or rising) edge of SCK10,
and output from the SO10 pin via an output selector. Then, the value of the SOTB10 register is transferred to the
SIO10 register at the next rising (or falling) edge of SCK10, and shifted one bit. At the same time, the first bit of
the receive data is stored in the SIO10 register via the SI10 pin.
The second and subsequent bits are latched by the SIO10 register to the output latch at the next falling (or rising)
edge of SCK10, and the data is output from the SO10 pin.
Writing to SOTB10 or
reading from SIO10
Output latch
The first bit is directly latched by the SOTB10 register at the falling edge of the write signal of the SOTB10
register or the read signal of the SIO10 register, and output from the SO10 pin via an output selector. Then, the
value of the SOTB10 register is transferred to the SIO10 register at the next falling (or rising) edge of SCK10, and
shifted one bit. At the same time, the first bit of the receive data is stored in the SIO10 register via the SI10 pin.
The second and subsequent bits are latched by the SIO10 register to the output latch at the next rising (or falling)
edge of SCK10, and the data is output from the SO10 pin.
322
CHAPTER 15 SERIAL INTERFACE CSI10
Figure 15-6. Output Operation of First Bit
(1) When CKP10 = 0, DAP10 = 0 (or CKP10 = 1, DAP10 = 0)
SCK10
SOTB10
SIO10
SO10
(2) When CKP10 = 0, DAP10 = 1 (or CKP10 = 1, DAP10 = 1)
SCK10
SOTB10
SIO10
SO10
Preliminary User's Manual U16315EJ1V0UD
First bit
First bit 2nd bit
2nd bit
3rd bit