FEDL2240DIGEST-02
OKI Semiconductor
2. Serial Interface
ML2240 Family
When selecting the serial interface, the I/O pins CS, WR, DI. SCK, RD, and DO are used as input pins to input
various commands and data, and as output pins to read out the status of the commands and data.
The micro-computer interface becomes effective when CS pin is set to “L” level.
To input the commands and data, “L” level is input to CS and WR pins followed by, from MSB, to DI pin in
synchronization with the input clock signal at SCK pin. Data at DI pin is captured inside the device on the
rising or falling edge of the clock at SCK pin. And the command is executed on the rising edge of the WR pin.
The selection of rising/falling edge of SCK clock is determined by the input level of the SCK pin on the falling
edge of the CS pin. If the SCK pin on the falling edge of the CS pin is at “L” level, the DI pin data is captured
inside the device on the rising edge of SCK clock. Conversely, if the SCK pin on the falling edge of the CS pin
is at “H” level, then the DI pin data is captured on the falling edge of SCK clock.
Command and Data Input Timings
• SCK Rising Edge Operation
CS (I)
WR (I)
DI (I)
D7 D6 D5 D4 D3 D2 D1 D0
SCK (I)
• SCK falling Edge Operation
CS (I)
WR (I)
DI (I)
D7 D6 D5 D4 D3 D2 D1 D0
SCK (I)
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