Output Operation Of First Bit - NEC 78K0 User Manual

(3) Timing of output to SO1n pin (first bit)
When communication is started, the value of transmit buffer register 1n (SOTB1n) is output from the SO1n pin.
The output operation of the first bit at this time is described below.
Writing to SOTB1n or
reading from SIO1n
Output latch
The first bit is directly latched by the SOTB1n register to the output latch at the falling (or rising) edge of SCK1n,
and output from the SO1n pin via an output selector. Then, the value of the SOTB1n register is transferred to the
SIO1n register at the next rising (or falling) edge of SCK1n, and shifted one bit. At the same time, the first bit of
the receive data is stored in the SIO1n register via the SI1n pin.
The second and subsequent bits are latched by the SIO1n register to the output latch at the next falling (or rising)
edge of SCK1n, and the data is output from the SO1n pin.
Writing to SOTB1n or
reading from SIO1n
Output latch
The first bit is directly latched by the SOTB1n register at the falling edge of the write signal of the SOTB1n
register or the read signal of the SIO1n register, and output from the SO1n pin via an output selector. Then, the
value of the SOTB1n register is transferred to the SIO1n register at the next falling (or rising) edge of SCK1n, and
shifted one bit. At the same time, the first bit of the receive data is stored in the SIO1n register via the SI1n pin.
The second and subsequent bits are latched by the SIO1n register to the output latch at the next rising (or falling)
edge of SCK1n, and the data is output from the SO1n pin.
µ
Remark n = 0: PD780143, 780144
µ
n = 0, 1: PD780146, 780148, 78F0148
CHAPTER 16 SERIAL INTERFACES CSI10 AND CSI11
Figure 16-11. Output Operation of First Bit
(1) When CKP1n = 0, DAP1n = 0 (or CKP1n = 1, DAP1n = 0)
SCK1n
SOTB1n
SIO1n
SO1n
(2) When CKP1n = 0, DAP1n = 1 (or CKP1n = 1, DAP1n = 1)
SCK1n
SOTB1n
SIO1n
SO1n
User's Manual U15947EJ2V0UD
First bit
*
First bit 2nd bit
2nd bit
3rd bit
375