AmMCL00XA
17
P R E L I M I NA R Y
Hardware Reset is initiated. Loading the sector erase
registers may be done in any sequence and with any
number of sectors (0 to 15).
A Reset command issued after the device has begun
execution stops the erase operation, but the data in the
sector will be undefined. In that case, restart the erase
on that sector and allow it to complete.
The automatic sector erase begins after the 80
μ
s time
out from the rising edge of the
WE#
(or
CE#
) pulse for
the last sector erase command pulse and terminates
when the data on D7 is “1” (see Write Operation Status
section) at which time the device returns to read mode.
Data Polling must be performed at an address within
any of the sectors being erased.
If DATA Polling or the Toggle Bit indicates the device
has been written with a valid Sector Erase command,
D3 may be used to determine if the sector erase timer
window is still open. If D3 is high (‘1’), the internally
controlled erase cycle has begun; attempts to write
subsequent commands to the device will be ignored
until the erase operation is completed as indicated by
the DATA Polling or Toggle Bit. If D3 is low (‘0’), the
device will accept additional sector erase commands.
To be certain the command has been accepted, the
software should check the status of D3 following each
Sector Erase command. If D3 was high on the second
status check, the command may not have been
accepted.
It is recommended that the user guarantee the time
between sector erase command writes be less than 80
μ
s by disabling the processor interrupts just for the
duration of the Sector Erase (30H) commands. This
approach will ensure that sequential sector erase
command writes will be written to the device while the
sector erase timer window is still open.
Figure 4 illustrates the Embedded Erase Algorithm
using typical command strings and bus operations.
Table 9.
Embedded Erase Algorithm
Figure 4.
Embedded Erase Algorithm
Note:
The latest release of the software drivers for AMD
Miniature Cards and devices may be downloaded from the
AMD web site at http://www.amd.com.
Embedded Program Algorithm
The Embedded Program setup is a four bus cycle oper-
ation that stages the addressed memory location or
memory device for automatic programming.
Once the Embedded Program setup operation is per-
formed, the next
WE#
pulse causes a transition to an
active programming operation. Addresses are inter-
nally latched on the falling edge of the
WE#
(or
CE#
)
pulse. Data is internally latched on the rising edge of
the
WE#
pulse. The rising edge of
WE#
also begins the
programming operation. The system is not required to
provide further control or timing. The device will auto-
matically provide an adequate internally generated
write pulse and verify margin. The automatic program-
ming operation is completed when the data on D7 of
the addressed memory sector or memory device is
equivalent to data written to this bit (see Write Opera-
tion Status section) at which time the device returns to
the Read mode (no write verify command is required).
Addresses are latched on the falling edge of
WE#
(or
CE#
)
during the Embedded Program command execu-
tion and hence the system is not required to keep the
addresses stable during the entire Programming opera-
tion. However, once the device completes the
Embedded Program operation, it returns to the Read
mode and addresses are no longer latched. Since a
verify valid data must occur on D7, at this particular
instant, the system is required to supply a valid address
input to the device. A system designer has three choices
to implement the Embedded Programming algorithm:
Bus
Operation
Command
Comments
Standby
Wait for V
CC
ramp
Write
Embedded Erase
command sequence
6 bus cycle operation
Read
Data Poll or check
BUSY# (RY/BY#)
to verify erasure
Write Embedded Erase
Command Sequence
(See Tables 5–7)
Data
Poll from Device
or wait for BUSY#
(RY/BY#)
Start
Erasure Complete
21138E-5