M50FW040 datasheet(27/53 Pages) STMICROELECTRONICS

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M50FW040

Status Register

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5.0.3

Erase status (Bit 5)

The Erase Status bit can be used to identify if the memory has applied the maximum

number of erase pulses to the block and still failed to verify that the block has erased

correctly. The Erase Status bit should be read once the Program/Erase Controller Status bit

is ‘1’ (Program/Erase Controller inactive).

When the Erase Status bit is ‘0’ the memory has successfully verified that the block has

erased correctly; when the Erase Status bit is ‘1’ the Program/Erase Controller has applied

the maximum number of pulses to the block and still failed to verify that the block has erased

correctly.

Once the Erase Status bit is set to ‘1’ the it can only be reset to ‘0’ by a Clear Status

Program or Erase command is issued, otherwise the new command will appear to fail.

5.0.4

Program status (Bit 4)

The Program Status bit can be used to identify if the memory has applied the maximum

number of program pulses to the byte and still failed to verify that the byte has programmed

correctly. The Program Status bit should be read once the Program/Erase Controller Status

bit is ‘1’ (Program/Erase Controller inactive).

When the Program Status bit is ‘0’ the memory has successfully verified that the byte has

programmed correctly; when the Program Status bit is ‘1’ the Program/Erase Controller has

applied the maximum number of pulses to the byte and still failed to verify that the byte has

programmed correctly.

Once the Program Status bit is set to ‘1’ it can only be reset to ‘0’ by a Clear Status Register

command or a hardware reset. If it is set to ‘1’ it should be reset before a new Program or

Erase command is issued, otherwise the new command will appear to fail.

5.0.5

VPP status (Bit 3)

The VPP Status bit can be used to identify an invalid voltage on the VPP pin during Program

and Erase operations. The VPP pin is only sampled at the beginning of a Program or Erase

operation. Indeterminate results can occur if VPP becomes invalid during a Program or

Erase operation.

When the VPP Status bit is ‘0’ the voltage on the VPP pin was sampled at a valid voltage;

when the VPP Status bit is ‘1’ the VPP pin has a voltage that is below the VPP Lockout

Voltage, VPPLK, the memory is protected; Program and Erase operation cannot be

performed.

Once the VPP Status bit set to ‘1’ it can only be reset to ‘0’ by a Clear Status Register

command or a hardware reset. If it is set to ‘1’ it should be reset before a new Program or

Erase command is issued, otherwise the new command will appear to fail.

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