UPSD3422_V01 datasheet(213/300 Pages) STMICROELECTRONICS

213 / 300 page

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UPSD3422, UPSD3433, UPSD3434, UPSD3454

PSD module

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28.5.11

Data polling

Polling on the Data Polling Flag Bit (DQ7) is a method of checking whether a program or

erase operation is in progress or has completed. Figure 71 shows the Data Polling

algorithm.

When the 8032 issues a program instruction sequence, the embedded algorithm within the

Flash memory array begins. The 8032 then reads the location of the byte to be programmed

in Flash memory to check status. The Data Polling Flag Bit (DQ7) of this location becomes

the compliment of Bit D7 of the original data byte to be programmed. The 8032 continues to

poll this location, comparing the Data Polling Flag Bit (DQ7) and monitoring the Error Flag

Bit (DQ5). When the Data Polling Flag Bit (DQ7) matches Bit D7 of the original data, then

the embedded algorithm is complete. If the Error Flag Bit (DQ5) is '1,' the 8032 should test

the Data Polling Flag Bit (DQ7) again since the Data Polling Flag Bit (DQ7) may have

changed simultaneously with the Error Flag Bit (DQ5) (see Figure 71).

The Error Flag Bit (DQ5) is set if either an internal time-out occurred while the embedded

algorithm attempted to program the byte (indicating a bad Flash cell) or if the 8032

attempted to program bit to logic ’1’ when that bit was already programmed to logic ’0’ (must

erase to achieve logic ’1’).

It is suggested (as with all Flash memories) to read the location again after the embedded

programming algorithm has completed, to compare the byte that was written to the Flash

memory with the byte that was intended to be written.

When using the Data Polling method during an erase operation, Figure 71 still applies.

However, the Data Polling Flag Bit (DQ7) is '0' until the erase operation is complete. A ’1’ on

the Error Flag Bit (DQ5) indicates a time-out condition on the Erase cycle, a ’0’ indicates no

error. The 8032 can read any location within the sector being erased to get the Data Polling

Flag Bit (DQ7) and the Error Flag Bit (DQ5).

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UPSD3422 Datasheet(PDF) 213 Page - STMicroelectronics