M29F102BB35N1 View Datasheet(PDF) - STMicroelectronics

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M29F102BB35N1

1 Mbit (64Kb x16, Boot Block) Single Supply Flash Memory

STMicroelectronics 

M29F102BB

STATUS REGISTER

Bus Read operations from any address always

read the Status Register during Program and

Erase operations. It is also read during Erase Sus-

pend when an address within a block being erased

is accessed.

The bits in the Status Register are summarized in

Table 6., Status Register Bits.

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

be used to identify whether the Program/Erase

Controller has successfully completed its opera-

tion or if it has responded to an Erase Suspend.

The Data Polling Bit is output on DQ7 when the

Status Register is read.

During Program operations the Data Polling Bit

outputs the complement of the bit being pro-

grammed to DQ7. After successful completion of

the Program operation the memory returns to

Read mode and Bus Read operations from the ad-

dress just programmed output DQ7, not its com-

plement.

During Erase operations the Data Polling Bit out-

puts ’0’, the complement of the erased state of

DQ7. After successful completion of the Erase op-

eration the memory returns to Read Mode.

In Erase Suspend mode the Data Polling Bit will

output a ’1’ during a Bus Read operation within a

block being erased. The Data Polling Bit will

change from a ’0’ to a ’1’ when the Program/Erase

Controller has suspended the Erase operation.

Figure 5., Data Polling Flowchart, gives an exam-

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

dress is the address being programmed or an

address within the block being erased.

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

identify whether the Program/Erase Controller has

successfully completed its operation or if it has re-

sponded to an Erase Suspend. The Toggle Bit is

output on DQ6 when the Status Register is read.

During Program and Erase operations the Toggle

Bit changes from ’0’ to ’1’ to ’0’, etc., with succes-

sive Bus Read operations at any address. After

successful completion of the operation the memo-

ry returns to Read mode.

During Erase Suspend mode the Toggle Bit will

output when addressing a cell within a block being

erased. The Toggle Bit will stop toggling when the

Program/Erase Controller has suspended the

Erase operation.

Figure 6., 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/Erase

Controller. The Error Bit is set to ’1’ when a Pro-

gram, Block Erase or Chip Erase operation 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 Register is read.

Note that the Program command cannot change a

bit set at ’0’ back to ’1’ and attempting to do so may

or may not set DQ5 at ‘1’. In both cases, a succes-

sive Bus Read operation will show the bit is still ‘0’.

One of the Erase commands must be used to set

all the bits in a block or in the whole memory from

’0’ to ’1’.

Erase Timer Bit (DQ3). The Erase Timer Bit can

be used to identify the start of Program/Erase

Controller operation during a Block Erase com-

mand. Once the Program/Erase Controller starts

erasing the Erase Timer Bit is set to ’1’. Before the

Program/Erase Controller starts the Erase Timer

Bit is set to ’0’ and additional blocks to be erased

may be written to the Command Interface. The

Erase Timer Bit is output on DQ3 when the Status

Register is read.

Alternative Toggle Bit (DQ2). The Alternative

Toggle Bit can be used to monitor the Program/

Erase controller during Erase operations. The Al-

ternative Toggle Bit is output on DQ2 when the

Status Register is read.

During Chip Erase and Block Erase operations the

Toggle Bit changes from ’0’ to ’1’ to ’0’, etc., with

successive Bus Read operations from addresses

within the blocks being erased. Once the operation

completes the memory returns to Read mode.

During Erase Suspend the Alternative Toggle Bit

changes from ’0’ to ’1’ to ’0’, etc. with successive

Bus Read operations from addresses within the

blocks being erased. Bus Read operations to ad-

dresses within blocks not being erased will output

the memory cell data as if in Read mode.

After an Erase operation that causes the Error Bit

to be set the Alternative Toggle Bit can be used to

identify which block or blocks have caused the er-

ror. The Alternative Toggle Bit changes from ’0’ to

’1’ to ’0’, etc. with successive Bus Read Opera-

tions from addresses within blocks that have not

erased correctly. The Alternative Toggle Bit does

not change if the addressed block has erased cor-

rectly.

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