S-7750C Datasheet, PDF (20/44 Pages) Seiko Instruments Inc – PROGRAMMABLE PORT CONTROLLER (PORT EXPANDER WITH BUILT-IN E2PROM CIRCUIT)

PROGRAMMABLE PORT CONTROLLER (PORT EXPANDER WITH BUILT-IN E²PROM CIRCUIT)
S-7750C
Rev.1.1_00
4. Acknowledgment
Data is transmitted sequentially in 8-bit. Changing the SDA line to “L” indicates that the devices on the system bus
have received data, thus the devices send an acknowledgment signal back during the 9th clock of cycle.
The S-7750C does not send an acknowledgment signal back during the Write operation.
SCL
(Input)
1
8
9
SDA
(Master device’s output)
SDA
(Output)
Start
Condition
Acknowledgment
signal output
Figure 23 Acknowledgment Output Timing 1
The both commands, reload command and switching access to register / E²PROM command are 1-byte, but inputting them
as the command 2-byte or more is possible by adding dummy data. However, the S-7750C executes the command at the
moment that it has loaded 9-bit. And in this case, inputting clock 2-byte or more after inputting these commands makes the
SDA pin set in high-impedance. However, in the acknowledgment timing, S-7750C sends acknowledgment signal back
regardless of the setting at R / W bit. Figure 24 shows the output timing of acknowledgment signal.
Start Condition
SCL
Stop Condition
SDA
High-Impedance
High-Impedance
Device Code
R/W
Command
(0000 or 0001)
Acknowledgement Signal from S-7750C
Figure 24 Acknowledgment Output Timing 2
20
Seiko Instruments Inc.