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 WINBOND
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12 page 
W29GL032C 6 7.2 Instruction Definitions The device operation can be initiated by writing specific address and data commands or sequences into the instruction register. The device will be reset to reading array data when writing incorrect address and data values or writing them in the improper sequence. The addresses will be latched on the falling edge of #WE or #CE, whichever happens later; while the data will be latched on the rising edge of #WE or #CE, whichever happens first. Please refer to timing waveforms. 7.2.1 Reading Array Data The default state after power up or a reset operation is the Read mode. To execute a read operation, the chip is enabled by setting #CE and #OE active and #WE high. At the same time, the required address or status register location is provided on the address lines. The system reads the addressed location contents on the Data IO pins after the tCE and tOE timing requirements have been met. Output data will not be accessible on the Data IO pins if either the device or it’s outputs are not enabled by #CE or #OE being High, and the outputs will remain in a tri- state condition. When the device completes an embedded memory operation (i.e., Program, automatic Chip Erase or Sector Erase) successfully, it will return to the Read mode and from any address in the memory array the data can be read. However, If the embedded operation fails to complete, by verifying the status register bit DQ5 (exceeds time limit flag) going high during the operations, at this time system should execute a Reset operation causing the device to return to Read mode. Some operating states require a reset operation to return to Read mode such as: • Time-out condition during a program or erase failed condition, indicated by the status register bit DQ5 going High during the operation. Failure during either of these states will prevent the device from automatically returning to Read mode. • During device Auto Select mode or CFI mode, a reset operation is required to terminate their operation. In the above two situations, the device will not return to the Read mode unless a reset operation is executed (either hardware reset or software reset instruction) or the system will not be able to read array data. The device will enter Erase-Suspended Read mode if the device receives an Erase Suspend instruction while in the Sector Erase state. The erase operation will pause (after a time delay not exceeding 20µs) prior to entering Erase-Suspend Read mode. At this time data can be programmed or read from any sector that is not being erased. Another way to verify device status is to read the addresses inside the sectors being erased. This will only provide the contents of the status register. Program operation during Erase-Suspend Read mode of valid sector(s) will automatically return to the Erase-Suspend Read mode upon successful completion of the program operation. An Erase Resume instruction must be executed to exit the Erase-Suspended Read mode, at which time suspended erase operations will resume. Erase operation will resume where it left off and continue until successful completion unless another Erase Suspend instruction is received. 7.2.2 Page Mode Read The Page Mode Read has page sizes of 16 bytes or 8 words. The higher addresses A[20:3] accesses the desired page. To access a particular word or byte in a page, it is selected by A[2:0] for word mode and A[2:0,A-1] for byte mode. Page mode can be turned on by keeping “page-read address” constant and changing the “intra-read page” addresses. The page access time is tAA or tCE, followed by tPA for the page read time. When #CE toggles, access time is tAA or tCE. |
