NEC UPD789426 Series User Manual page 246

CHAPTER 12 SERIAL INTERFACE 20
Figure 12-11. 3-Wire Serial I/O Mode Timing (4/7)
(vi) Slave operation (when DAP20 = 0, CKP20 = 1, SSE20 = 1)
SS20
SIO20
write
SCK20
1 2 3 4 5 6 7 8
Note 1
SIO20 write (master)
SI20
DI7 DI6 DI5 DI4 DI3 DI2 DI1 DI0
Hi-Z Hi-Z
Note 2
DO7 DO6 DO5 DO4 DO3 DO2 DO1 DO0
SO20
INTCSI20
Notes 1. The data of SI20 is loaded at the first rising edge of SCK20. Make sure that the master outputs
the first bit before the first rising of SCK20.
2. SO20 is high until SS20 rises after completion of DO0 output. When SS20 is high, SO20 is in a
high-impedance state.
(vii) Master operation (when DAP20 = 1, CKP20 = 0, SSE20 = 0)
SIO20
write
1 2 3 4 5 6 7 8
SCK20
SO20
DO7 DO6 DO5 DO4 DO3 DO2 DO1 DO0
SI20 DI7 DI6 DI5 DI4 DI3 DI2 DI1 DI0
INTCSI20
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User's Manual U15075EJ2V1UD