28F002BC 2-MBIT BOOT BLOCK FLASH MEMORY
E
14
PRELIMINARY
3.2.2
INTELLIGENT IDENTIFIERS
The manufacturer and device codes are read via
the CUI or by taking the A
9
pin to V
ID
. Writing 90H
to the CUI places the device into Intelligent
Identifier read mode. A read of location 00000H
outputs the manufacturer’s identification code, 89H.
Reading location 00001H outputs the device ID,
7CH.
The 28F002BC device ID of 7CH is identical to the
E28F002BX (40-lead TSOP). It differs from the
PA28F200BX (44-lead PSOP), which has a device
ID of 2274H. Designers using the PA28F200BX in
the x8 mode who wish to migrate to the
PA28F002BC need to be mindful of this device ID
difference
and
modify
necessary. The 40-lead PDIP device ID is 7CH.
software
drivers
as
3.3
Write Operations
There are two commands that alter memory array
contents: Program Setup and Erase Setup/Confirm.
In addition, the Erase Suspend command suspends
the WSM during an erase operation and releases
the CUI to accept any Read command (so long as it
is to a block other than the one being erased).
Finally, there is a Clear Status Register command
for resetting the contents of the status register. This
command
should
be
operations that modify the status register.
invoked
following
all
All commands written to the CUI will be interpreted,
but for any write operation to be initiated, the V
PP
voltage must be at V
HH
. Depending on the
application, the design may have a switchable V
PP
power supply or the V
PP
may be “hard-wired” to
12V. The 28F002BC will function normally in either
case. It is highly recommended that RP# is tied to
the system RESET for data protection during
unstable CPU reset and also for proper CPU / flash
synchronization.
Furthermore, when attempting to modify the
contents of the 28F002BC’s boot block area, V
HH
must be applied to both V
PP
and RP# for the
operation to be valid. Whether attempting to alter
the contents of the boot block or any other memory
array area, if the proper voltages are not applied to
the correct input signals the write operation will be
aborted. Subsequently, the status register will
respond with either Bit 3 (V
PP
low error), Bit 4
(program error) or Bit 5 (erase error) being set (refer
to Table 5 for status register definitions).
3.3.1
COMMAND USER INTERFACE (CUI)
The Command User Interface (CUI) serves as the
interface between the microprocessor and the
internal chip controller. Commands are written to
the CUI using standard microprocessor write
timings. The available commands (summarized in
Tables 3 and 4) are Read Array, Read Intelligent
Identifier, Read Status Register, Clear Status
Register, Program Setup, Erase Setup/Confirm,
and Erase Suspend.
For Read commands, the CUI points the read path
at either the array, the intelligent identifier, or the
status register depending on the command
received. For Program or Erase commands, the
CUI informs the Write State Machine (WSM) that a
Program or Erase has been requested. During the
execution of a Program command, the WSM
controls the programming sequences and the CUI
responds only to status register reads. During an
erase cycle, the CUI responds only to status
register reads and Erase Suspend. After the WSM
has completed its task, it will set the WSM Status
bit (bit 7 of the status register) to a “1,” which will
also allow the CUI to respond to its full command
set. Note that after the WSM has returned control to
the CUI, the CUI will stay in the read status register
mode until it receives another command (see
Appendix B).
Table 3. Command Set Codes and
Corresponding Device Mode
Command Codes
Device Mode
00
Invalid/Reserved
20
Erase Setup
40
Program Setup
50
Clear Status Register
70
Read Status Register
90
Intelligent Identifier
B0
Erase Suspend
D0
Erase Resume/Erase Confirm
FF
Read Array