ID242 Datasheet, PDF (13/33 Pages) Sharp Electrionic Components – Flash Memory Card

SHARP
ID242 SERIES PRODUCT OVERVIEW
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8. Card Control
8. 1 Reset
The card is in initial state directly after power-up. But we recommend to do reset operation after power-up to
make sure to initialize the card.
During block erase, byte write, or lock-bit configuration modes, an active RESET will abort the operation. RDYI
BSY# remains low until the reset operation completes. Memory contents being altered are no longer valid; the
data may be partially erased or written. The host must wait after RESET goes to logic-Low (Vu) before it can
write another command, as determined by tPHWL.
It is important to assert RESET to the card during a system reset. If a CPU reset occurs without a card reset, the
host will not be able to read from the card if that card is in a different mode when the system reset occurs.
For example, if an end-user initiates a host reset when the card is in read status register mode, the host will attempt
to read code from the card, but will actually read status register data. Sharp’s ID242 Series Flash Memory Card
allows proper card reset following a system reset through the use of the RESET input.
8. 2 Status Register
Each flash memory device in the card has status register. The status register may be read to determine when a
write, block erase, or lock-bits configuration is complete, and whether that operation completed successfully
(please refer to Table 10). It may be read at any time by writing the Read Status Register command (70h, 7070h)
into the CUI. In word access mode, the status register data of even byte devices are output to D7-0,and the status
register data of odd byte devices are output to D15-8.
8. 3 Write Protect Switch
The ID242 Series Flash Memory Card has a write protect switch on the back of the card. When the switch is in the
write protect position, the card blocks all writes to the common and attribute memory without Card Management
Registers region (see Figure 5).
8. 4 Read identifier Codes / Lock bits Information
Manufacture Code and Device Code are contained within each flash memory device in the memory card. The
identifier code operation is initiated by writing the Read Identifier Codes command (90h, 9090h) into the CUI of
each memory device. The specific address of each device is necessary to be selected to read these codes (Table 8).
F1005-01
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Writeble position
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Write protZ&ition
Note: The write protect switch is shown by the black square.
Figure 4. Write Protect Switch
CPS0002.002@May.1998