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¡ Semiconductor

MSM6794

FUNCTIONAL DESCRIPTION

Pin Functional Description

•CS (Chip Select)

Chip select input pin. "L" is for Select, "H" is for Unselect. Internal registers can be accessed

only when this pin is at "L".

When this pin is "H", the SO pin becomes high impedance.

•WR (Write Enable)

This is a write signal input pin when a parallel interface is used. Data is written to a register

at the rising edge of a signal pulse.

This becomes a latch signal input pin when a serial interface is used.

This pin is normally "H".

•RD (Read Enable)

This is a read signal input pin when a parallel interface is used. Data can be read while the pulse

is "L". This pin is normally "H".

Set this pin to "H" or "L" when a serial interface is used.

•RS (Register Select)

Input pin to select register. Setting this pin to "L" selects the address register. Setting to "H"

selects a register set by the address register.

If this pin is changed from "H" to "L" while a serial interface is used, the SERW bit (D4 bit) of

the address register is automatically reset to "0".

•DB0 to DB7 (Data Buses 0 to 7)

Data input/output pins for parallel interface. These pins are normally in high impedance

status. When RD = "L", each register data is output.

Leave this pin open when a serial interface is used.

•SI (Serial Data Input)

Data input pin for serial interface. Each register data and display data are read at the rising edge

of SHT, and written to the register at the falling edge of WR. 8-bit data just before the rise of

WR is valid data.

Set this pin to "H" or "L" when a parallel interface is used.

•SO (Serial Data Output)

Data output pin for serial interface. Each register data is output synchronizing with the rise of

SHT. For busy/non-busy data, busy ("H") is output after the rise of WR, and automatically

becomes non-busy ("L") after a specified time.

This pin is always in high impedance status when a parallel interface is used.

•SHT (Shift Clock)

Clock input pin for serial interface data input/output. Data is input synchronizing with the

rise of the clock, and data is output synchronizing with the fall of the clock.

This pin is normally in "H".

Set this pin to "H" or "L" when a parallel interface is used.

•P/S (Parallel/Serial Select)

Input pin for selecting parallel interface or serial interface. Setting this pin to "L" selects parallel

interface. Setting to "H" selects serial interface. Do not change the setting value after power

is turned on.