M93S46-W Datasheet, PDF (10/32 Pages) STMicroelectronics – 4 Kbit, 2 Kbit and 1 Kbit serial MICROWIRE bus EEPROM with write protection

Instructions
M93S46-W M93S56-W M93S66­W
5
Instructions
The instruction set of the M93Sx6 devices contains seven instructions, as summarized in
Table 2: "Instruction set for the M93S46" and Table 3: "Instruction set for the M93S66,
M93S56". Each instruction consists of the following parts, as shown in Figure 4: "READ
sequence", Figure 5: "WRITE sequence" and Figure 6: "WEN and WDS sequences":
• Each instruction is preceded by a rising edge on Chip Select Input (S) with Serial
Clock (C) being held Low.
• A start bit, which is the first '1' read on Serial Data Input (D) during the rising edge of
Serial Clock (C).
• Two op-code bits, read on Serial Data Input (D) during the rising edge of Serial Clock
(C). (Some instructions also use the first two bits of the address to define the
op­code).
• The address bits of the byte or word that is to be accessed. For the M93S46, the
address is made up of 6 bits (see Table 2: "Instruction set for the M93S46"). For the
M93S56 and M93S66, the address is made up of 8 bits (see Table 3: "Instruction set
for the M93S66, M93S56").
The M93Sx6 devices are fabricated in CMOS technology and are therefore able to run as
slow as 0 Hz (static input signals) or as fast as the maximum ratings specified in Table 11:
"AC Characteristics (M93Sx6-W, device grade 6)".
Instruction Description
Table 2: Instruction set for the M93S46
W
PRE
Start
bit
Op-
code
Address
(1)
Data
Required
clock
cycles
Additional
comments
READ
Read Data
from Memory
X
0
1
10 A5­A0 Q15­Q0
­
-
Write is executed
WRITE
Write Data to
Memory
1
0
1
01 A5­A0 D15­D0
25
if the address is
not inside the
Protected area
Write is executed
PAWRITE
Page Write to
Memory
1
0
1
Nx
if all the N
11 A5­A0
9 + N x 16 addresses are not
D15­D0
inside the
Protected area
WRAL
Write All
Memory with 1 0
1
00 01 XXXX D15­D0
same Data
Write all data if
25
the Protection
Register is
cleared
WEN
Write Enable 1 0
1
00 11 XXXX
-
9
-
WDS
Write Disable X 0
1
00 00 XXXX
-
9
-
PRREAD
Protection
Register Read
X
1
1
10
XXXXXX
Q5­Q0
+ Flag
Data Output =
-
Protection
Register content +
Protection Flag bit
PRWRITE
Protection
Register Write
1
1
1
01 A5­A0
-
Data above
9
specified address
A5-A0 are
protected
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