NEC PD750008 - Manual (Page 191)

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CHAPTER 5 PERIPHERAL HARDWARE FUNCTIONS
Figure 5-69. Data Transfer Operation from Master Device to Slave Device
Program processing Hardware operation Program processing
SCK pin
12
345
6
78
9
SB0 or SB1 pin
D7
Hardware operation
D6
D5
D4
D3
D2
D1
D0
ACK
READY
Data
Master device processing (transmitter) Transfer line Slave device processing (receiver)
Interrupt handling (preparation for next serial transfer)
Serial transmission
Generate IRQCSI
Serial reception
Generate IRQCSI
BUSY
Write to SIO
Set ACKD
Stop SCK
Read SIO
Set ACKT
Clear BUSY
Output BUSY
Output ACK
Clear BUSY