AM29F032B_09 datasheet(21/40 Pages) SPANSION

21 / 40 page

November 11, 2009 21610D8

Am29F032B

D A TA

SH EE T

RY/BY#: Ready/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, sev-

eral 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 6 shows the outputs for RY/BY#. The timing dia-

grams for read, reset, program, and erase shows the

relationship of RY/BY# to other signals.

DQ6: Toggle Bit I

Toggle Bit I on DQ6 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 op-

eration), and during the sector erase time-out.

During an Embedded Program or Erase algorithm op-

eration, successive read cycles to any address cause

DQ6 to toggle. (The system may use either OE# or

CE# to control the read cycles.) When the operation is

complete, DQ6 stops toggling.

After an erase command sequence is written, if all

sectors selected for erasing are protected, DQ6 tog-

gles for approximately 100 µs, then returns to reading

array data. If not all selected sectors are protected,

the Embedded Erase algorithm erases the unpro-

tected sectors, and ignores the selected sectors that

are protected.

The system can use DQ6 and DQ2 together to deter-

mine 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), DQ6

toggles. When the device enters the Erase Suspend

mode, DQ6 stops toggling. However, the system must

also use DQ2 to determine which sectors are erasing

or erase-suspended. Alternatively, the system can use

DQ7 (see the subsection on “DQ7: Data# Polling”).

If a program address falls within a protected sector,

DQ6 toggles for approximately 2 µs after the program

command sequence is written, then returns to reading

array data.

DQ6 also toggles during the erase-suspend-program

mode, and stops toggling once the Embedded Pro-

gram algorithm is complete.

The Write Operation Status table shows the outputs for

Toggle Bit I on DQ6. Refer to Figure 5 for the toggle bit

algorithm, and to the Toggle Bit Timings figure in the

“AC Characteristics” section for the timing diagram.

The DQ2 vs. DQ6 figure shows the differences be-

tween DQ2 and DQ6 in graphical form. See also the

subsection on “DQ2: Toggle Bit II”.

DQ2: Toggle Bit II

The “Toggle Bit II” on DQ2, when used with DQ6, indi-

cates 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.

DQ2 toggles when the system reads at addresses

within those sectors that have been selected for era-

sure. (The system may use either OE# or CE# to con-

trol the read cycles.) But DQ2 cannot distinguish

whether the sector is actively erasing or is erase-sus-

pended. DQ6, by comparison, indicates whether the

device is actively erasing, or is in Erase Suspend, but

cannot distinguish which sectors are selected for era-

sure. Thus, both status bits are required for sector and

mode information. Refer to Table 6 on page 22 to com-

pare outputs for DQ2 and DQ6.

Figure 5, on page 20 shows the toggle bit algorithm in

flowchart form, and the section “DQ2: Toggle Bit II” ex-

plains the algorithm. See also the “DQ6: Toggle Bit I”

subsection. Refer to the Toggle Bit Timings figure for

the toggle bit timing diagram. The DQ2 vs. DQ6 figure

shows the differences between DQ2 and DQ6 in graph-

ical form.

Reading Toggle Bits DQ6/DQ2

Refer to Figure 5, on page 20 for the following discus-

sion. Whenever the system initially begins reading

toggle bit status, it must read DQ7–DQ0 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 oper-

ation. The system can read array data on DQ7–DQ0

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 DQ5 is

high (see the section on DQ5). If it is, the system

should then determine again whether the toggle bit is

toggling, since the toggle bit may have stopped tog-

gling just as DQ5 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

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