UPD784044 Datasheet, PDF (38/90 Pages) NEC – 16-BIT SINGLE-CHIP MICROCONTROLLER

µPD784044(A), 784046(A)
(2) 3-wire serial I/O mode
This mode is to start transmission when the master device makes a serial clock active and to communicate
1-byte data in synchronization with this clock.
The interface in this mode communicates with devices that have conventional clocked serial interface.
Basically, communication is performed by using three lines: serial clock (SCK) and two serial data (SI and
SO) lines. To connect two or more devices, a handshake line is necessary.
Figure 7-9. Block Diagram in 3-Wire Serial I/O Mode
Internal bus
SI1, SI2
Direction control circuit
SIO1, SIO2
Shift register
Output latch
SO1, SO2
SCK1, SCK2
Serial clock counter
Serial clock
control circuit
Interrupt
generation circuit
INTCSI1,
INTCSI2
1/2m
1/2ⁿ⁺¹
fCLK
Remark fCLK: internal system clock
n = 0 to 11
m = 1, 16 to 30
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