M27W032 datasheet(12/23 Pages) STMICROELECTRONICS

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M27W032

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STATUS REGISTER

Bus Read operations from any address always

read the Status Register during Program opera-

tions. The bits in the Status Register are summa-

rized in Table 6, Status Register Bits.

Data Polling Bit (DQ7). The Data Polling Bit can

be used to identify whether the Program Controller

has successfully completed its operation. The

Data Polling Bit is output on DQ7 when the Status

During a Word Program operation the Data Polling

Bit outputs the complement of the bit being pro-

grammed to DQ7. After successful completion of

the Word Program operation the memory returns

to Read mode and Bus Read operations from the

address just programmed output DQ7, not its com-

plement.

Figure 6, Data Polling Flowchart, gives an exam-

ple of how to use the Data Polling Bit. A Valid Ad-

dress is the address being programmed.

Toggle Bit (DQ6). The Toggle Bit can be used to

identify whether the Program Controller has suc-

cessfully completed its operation. The Toggle Bit

is output on DQ6 when the Status Register is read.

During Program operations the Toggle Bit chang-

es from ’0’ to ’1’ to ’0’, etc., with successive Bus

Read operations at any address. After successful

completion of the operation the memory returns to

Read mode.

Figure 7, Data Toggle Flowchart, gives an exam-

ple of how to use the Data Toggle Bit.

Error Bit (DQ5). The Error Bit can be used to

identify errors detected by the Program Controller.

The Error Bit is set to ’1’ when a Program opera-

tion fails to write the correct data to the memory. If

the Error Bit is set a Read/Reset command must

be issued before other commands are issued. The

Error bit is output on DQ5 when the Status Regis-

ter is read.

Note that the Program command cannot change a

bit set to ’0’ back to ’1’ and attempting to do so will

set DQ5 to ‘1’. A Bus Read operation to that ad-

dress will show the bit is still ‘0’.

VPP Status Bit (DQ4). The VPP Status Bit can be

used to identify if any Program operation has failed

due to a VPP error. If VPP falls below VHH during

any Program operation, the operation aborts and

DQ4 is set to ‘1’. If VPP remains at VHH throughout

the Program operation, the operation completes

and DQ4 is set to ‘0’.

Multiple Word Program Bit (DQ0). The Multiple

Word Program Bit can be used to indicate whether

the Program Controller is active or inactive during

Multiple Word Program. When the Program Con-

troller has written one Word and is ready to accept

the next Word, the bit is set to ‘0’.

Status Register Bit DQ1 is reserved.

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