ACE25C200

2MB Serial Flash Memory

VER 1.2

12

Figure 6 Write disable instruction

Read status register (RDSR) (05h)

The Read Status Register instructions allow the 8-bit Status Registers to be read. The instruction is

entered by driving CS# low and shifting the instruction code “05h” into the DI pin on the rising edge of

CLK. The status register bits are then shifted out on the DO pin at the falling edge of CLK with most

significant bit (MSB) first as shown in Figure 7. The Status Register bits are shown in Figure 4 and

include the WIP, WEL, BP2-BP0 and SRP bits.

The Read Status Register instruction may be used at any time, even while a Program, Erase or Write

Status Register cycle is in progress. This allows the WIP status bit to be checked to determine when

the cycle is complete and if the device can accept another instruction. The Status Register can be

read continuously. The instruction is completed by driving CS# high.

Figure 7 Read status register instruction

Write Status Register (WRSR) (01h)

The Write Status Register (WRSR) instruction allows the Status Register to be written. Only

non-volatile Status Register bits SRP, BP2, BP1, BP0 can be written to. All other Status Register bit

locations are read-only and will not be affected by the Write Status Register (WRSR) instruction. The

Status Register bits are shown in Figure 4, and described in 10 Status Register.