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A29L161B Datasheet(PDF) 20 Page - AMIC Technology |
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A29L161B Datasheet(HTML) 20 Page - AMIC Technology |
20 / 41 page ![]() A29L161B Series (December, 2015, Version 1.0) 19 AMIC Technology, Corp. RY/ BY : Read/Busy The RY/ BY is a dedicated, open-drain output pin that indicates whether an Embedded algorithm is in progress or complete. The RY/ BY status is valid after the rising edge of the final WE pulse in the command sequence. Since RY/ BY is an open-drain output, several RY/ BY pins can be tied together in parallel with a pull-up resistor to VCC. If the output is low (Busy), the device is actively erasing or programming. (This includes programming in the Erase Suspend mode.) If the output is high (Ready), the device is ready to read array data (including during the Erase Suspend mode), or is in the standby mode. Table 10 shows the outputs for RY/ BY . Refer to “RESET Timings”, “Timing Waveforms for Program Operation” and “Timing Waveforms for Chip/Sector Erase Operation” for more information. I/O6: Toggle Bit I Toggle Bit I on I/O6 indicates whether an Embedded Program or Erase algorithm is in progress or complete, or whether the device has entered the Erase Suspend mode. Toggle Bit I may be read at any address, and is valid after the rising edge of the final WE pulse in the command sequence (prior to the program or erase operation), and during the sector erase time-out. During an Embedded Program or Erase algorithm operation, successive read cycles to any address cause I/O6 to toggle. (The system may use either OE or CE to control the read cycles.) When the operation is complete, I/O6 stops toggling. After an erase command sequence is written, if all sectors selected for erasing are protected, I/O6 toggles for approximately 100 μs, then returns to reading array data. If not all selected sectors are protected, the Embedded Erase algorithm erases the unprotected sectors, and ignores the selected sectors that are protected. The system can use I/O6 and I/O2 together to determine whether a sector is actively erasing or is erase-suspended. When the device is actively erasing (that is, the Embedded Erase algorithm is in progress), I/O6 toggles. When the device enters the Erase Suspend mode, I/O6 stops toggling. However, the system must also use I/O2 to determine which sectors are erasing or erase-suspended. Alternatively, the system can use I/O7 (see the subsection on " I/O7 : Data Polling"). If a program address falls within a protected sector, I/O6 toggles for approximately 2 μs after the program command sequence is written, then returns to reading array data. I/O6 also toggles during the erase-suspend-program mode, and stops toggling once the Embedded Program algorithm is complete. The Write Operation Status table shows the outputs for Toggle Bit I on I/O6. Refer to Figure 6 for the toggle bit algorithm, and to the Toggle Bit Timings figure in the "AC Characteristics" section for the timing diagram. The I/O2 vs. I/O6 figure shows the differences between I/O2 and I/O6 in graphical form. See also the subsection on " I/O2: Toggle Bit II". I/O2: Toggle Bit II The "Toggle Bit II" on I/O2, when used with I/O6, indicates whether a particular sector is actively erasing (that is, the Embedded Erase algorithm is in progress), or whether that sector is erase-suspended. Toggle Bit II is valid after the rising edge of the final WE pulse in the command sequence. I/O2 toggles when the system reads at addresses within those sectors that have been selected for erasure. (The system may use either OE or CE to control the read cycles.) But I/O2 cannot distinguish whether the sector is actively erasing or is erase-suspended. I/O6, by comparison, indicates whether the device is actively erasing, or is in Erase Suspend, but cannot distinguish which sectors are selected for erasure. Thus, both status bits are required for sector and mode information. Refer to Table 10 to compare outputs for I/O2 and I/O6. Figure 6 shows the toggle bit algorithm in flowchart form, and the section " I/O2: Toggle Bit II" explains the algorithm. See also the " I/O6: Toggle Bit I" subsection. Refer to the Toggle Bit Timings figure for the toggle bit timing diagram. The I/O2 vs. I/O6 figure shows the differences between I/O2 and I/O6 in graphical form. Reading Toggle Bits I/O6, I/O2 Refer to Figure 6 for the following discussion. Whenever the system initially begins reading toggle bit status, it must read I/O7 - I/O0 at least twice in a row to determine whether a toggle bit is toggling. Typically, a system would note and store the value of the toggle bit after the first read. After the second read, the system would compare the new value of the toggle bit with the first. If the toggle bit is not toggling, the device has completed the program or erase operation. The system can read array data on I/O7 - I/O0 on the following read cycle. However, if after the initial two read cycles, the system determines that the toggle bit is still toggling, the system also should note whether the value of I/O5 is high (see the section on I/O5). If it is, the system should then determine again whether the toggle bit is toggling, since the toggle bit may have stopped toggling just as I/O5 went high. If the toggle bit is no longer toggling, the device has successfully completed the program or erase operation. If it is still toggling, the device did not complete the operation successfully, and the system must write the reset command to return to reading array data. The remaining scenario is that the system initially determines that the toggle bit is toggling and I/O5 has not gone high. The system may continue to monitor the toggle bit and I/O5 through successive read cycles, determining the status as described in the previous paragraph. Alternatively, it may choose to perform other system tasks. In this case, the system must start at the beginning of the algorithm when it returns to determine the status of the operation (top of Figure 6). I/O5: Exceeded Timing Limits I/O5 indicates whether the program or erase time has exceeded a specified internal pulse count limit. Under these conditions I/O5 produces a "1." This is a failure condition that indicates the program or erase cycle was not successfully completed. The I/O5 failure condition may appear if the system tries to program a "1 "to a location that is previously programmed to "0." Only an erase operation can change a "0" back to a "1." Under this condition, the device halts the operation, and when the operation has exceeded the timing limits, I/O5 produces a "1." Under both these conditions, the system must issue the reset command to return the device to reading array data. |
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