UPSD3254 STMICROELECTRONICS [STMicroelectronics], UPSD3254 Datasheet - Page 107

• Manufacturer Part Number: UPSD3254
• Description: Flash Programmable System Devices with 8032 Microcontroller Core
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

Instructions
An instruction consists of a sequence of specific
operations. Each received byte is sequentially de-
coded by the PSD MODULE and not executed as
a standard WRITE operation. The instruction is ex-
ecuted when the correct number of bytes are prop-
erly
consecutive bytes is shorter than the time-out pe-
riod. Some instructions are structured to include
READ operations after the initial WRITE opera-
tions.
The instruction must be followed exactly. Any in-
valid combination of instruction bytes or time-out
between two consecutive bytes while addressing
Flash memory resets the device logic into READ
Mode (Flash memory is read like a ROM device).
The Flash memory supports the instructions sum-
marized in Table 85:
Flash memory:
Erase memory by chip or sector
Suspend or resume sector erase
Program a Byte
RESET to READ Mode
received
and
the
time
between
UPSD3254A, UPSD3254BV, UPSD3253B, UPSD3253BV
two
These instructions are detailed in Table 85. For ef-
ficient decoding of the instructions, the first two
bytes of an instruction are the coded cycles and
are followed by an instruction byte or confirmation
byte. The coded cycles consist of writing the data
AAh to address X555h during the first cycle and
data 55h to address XAAAh during the second cy-
cle. Address signals A15-A12 are Don’t Care dur-
ing the instruction WRITE cycles. However, the
appropriate
CSBOOT0-CSBOOT3) must be selected.
The primary and secondary Flash memories have
the same instruction set (except for Read Primary
Flash Identifier). The Sector Select signals deter-
mine which Flash memory is to receive and exe-
cute the instruction. The primary Flash memory is
selected if any one of Sector Select (FS0-FS7) is
High, and the secondary Flash memory is selected
if
CSBOOT3) is High.
Read Sector Protection Status
Bypass
any
one
Sector
of
Sector
Select
Select
(FS0-FS7
(CSBOOT0-
107/175
or