6

3354F–FLASH–2/05

AT49F002A(N)(T)

4.7

Product Identification

The product identification mode identifies the device and manufacturer as Atmel. It may be

accessed by hardware or software operation. The hardware operation mode can be used by an

external programmer to identify the correct programming algorithm for the Atmel product.

For details, see Operating Modes (for hardware operation) or Software Product Identification.

The manufacturer and device code is the same for both modes.

4.8

DATA Polling

The AT49F002A(N)(T) features DATA polling to indicate the end of a program cycle. During a

program cycle an attempted read of the last byte loaded will result in the complement of the

loaded data on I/O7. Once the program cycle has been completed, true data is valid on all out-

puts and the next cycle may begin. DATA polling may begin at any time during the program

cycle.

4.9

Toggle Bit

In addition to DATA polling the AT49F002A(N)(T) provides another method for determining the

end of a program or erase cycle. During a program or erase operation, successive attempts to

read data from the device will result in I/O6 toggling between one and zero. Once the program

cycle has completed, I/O6 will stop toggling and valid data will be read. Examining the toggle bit

may begin at any time during a program cycle.

4.10

Hardware Data Protection

Hardware features protect against inadvertent programs to the AT49F002A(N)(T) in the

following ways: (a) V

(b) Program inhibit: holding any one of OE low, CE high or WE high inhibits program cycles.

(c) Noise filter: pulses of less than 15 ns (typical) on the WE or CE inputs will not initiate a pro-

gram cycle.