Toggle Bit (D6) - Philips CEM2100/00 Service Manual

It takes a maximum of 40 µs to set security program in the flash memory. The next command sequence can-
not be executed until this operation is completed. To check the completion of the security program operation,
perform read operations repeatedly for data polling until the same data is read twice from the same address in
the flash memory. During the security program operation, any attempts to read from the same address is
reversed bit 6 of the data (toggling between 0 and 1).

19.3 Toggle Bit (D6)

After the byte program, chip erase, and security program command sequence is executed, any consecutive
attempts to read from the same address is reversed bit 6 (D6) of the data (toggling between 0 and 1) until the opera-
tion is completed. Therefore, this toggle bit provides a software mechanism to check the completion of each opera-
tion. Usually perform read operations repeatedly for data polling until the same data is read twice from the same
address in the flash memory. After the byte program, chip erase, or security program command sequence is executed,
the initial read of the toggle bit always produces a "1".
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