NEC PD78214 - Manual (Page 308)

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Chapter 10 Clock Synchronous Serial Interface
10
10.6.4 Command and Data
The master device sends commands to, and sends or receives data to or from, the slave device selected according
to the specified address.
Fig. 10-18 Command
SCK
SB0
1 2 3 4 5 6 7 8
Command
C7 C6 C5 C4 C3 C2 C1 C0
Command signal
Fig. 10-19 Data
SCK
SB0
1 2 3 4 5 6 7 8
Data
D7 D6 D5 D4 D3 D2 D1 D0
SCK
SB0
8 9 10 11
ACK
[Output in synchronization with the ninth pulse of the SCK clock]
SCK
SB0
8 9
ACK
The acknowledge signal is a one-shot pulse, synchronized with the falling edge of SCK after the 8-bit data is
transferred. The signal can be synchronized with the SCK clock pulse at a desired position.
After sending the 8-bit data, the transmitting device checks whether the receiving device returns the acknowledge
signal. If the receiving device does not return the acknowledge signal within a certain period after the data is sent,
the device has not successfully received the data.
The 8-bit data following the command signal is defined as a command. The 8-bit data without the command signal
is defined as data. The use of the command and data can be determined according to the communication
specifications.
10.6.5 Acknowledge Signal (ACK)
The transmitting device and receiving device use the acknowledge signal to check whether the data is successfully
received.
Fig. 10-20 Acknowledge Signal
[Output in synchronization with the eleventh pulse of the SCK clock]