ASAHI KASEI

[AK9844]

DAD02E-00

1999/05

- 9 -

„ READ

The read instruction is the only instruction which outputs serial data on the DO pin.

After a read instruction is received, the instruction and address are decoded, followed by data transfer from

the memory register into a 16 bit serial-out shift register. When the 17th falling edge of SK is received, the Do

pin will come out of high impedance state and shift out the data from D15 first in descending order which is

located at the address specified in the instruction.

{ Sequential register read

The data in the next address can be read sequentially to provide clock. The memory automatically cycles

to the next register after each 16 data bits are clocked out.

The sequential register read function is effective for address:A7

∼A0. When the highest address is

reached($0FF/$103), the address counter rolls over to address $000/$100 allowing the read cycle to be

continued indefinitely.

READ instruction

„ WREN/WRDS

When Vcc is applied to the part, it powers up in the programming disable(WRDS) state.

Programming must be preceded by a programming enable(WREN) instruction. Programming remains enabled

until a programming disable(WRDS) instruction is executed or Vcc is removed from the part. The

programming disable instruction is provided to protect against accidental data disturb. Execution of a read

instruction is not affected by both WREN and WRDS instruction.

WREN/WRDS instruction