M34E04B Datasheet, PDF (12/35 Pages) STMicroelectronics – 4-Kbit Serial Presence Detect EEPROM compatible

Device operation
M34E04B
Table 2. Device Type Identifier Code (DTIC)
Abbr
Device type identifier
(1)
b7 b6 b5 b4
Select address
(2) (3)
b3 b2 b1
R_W_n
b0
SA0 pin
(4)
Read
Write
RSPD
1
1
0
1
0 LSA2 LSA1 LSA0
WSPD
0
0 or 1
Set Write Protection, block 0
SWP0
0
0
1
0
V_HV
Set Write Protection, block 1
SWP1
1
0
0
0
V_HV
Set Write Protection, block 2
SWP2
1
0
1
0
V_HV
Set Write Protection, block 3
SWP3
0
0
0
0
V_HV
Clear All Write Protection
CWP
0
1
1
Read Protection Status, block 0 ⁽⁵⁾ RPS0
0
0
1
Read Protection Status, block 1 ⁽⁵⁾ RPS1 0
1
1
0
1
0
0
Read Protection Status, block 2 ⁽⁵⁾ RPS2
1
0
1
Read Protection Status, block 3 ⁽⁵⁾ RPS3
0
0
0
Set Page Address to 0 ⁽⁶⁾
SPA0
1
1
0
Set Page Address to 1 ⁽⁶⁾
SPA1
1
1
1
Read Page Address ⁽⁷⁾
RPA
1
1
0
0
V_HV
1 0, 1 or V_HV
1 0, 1 or V_HV
1 0, 1 or V_HV
1 0, 1 or V_HV
0 0, 1 or V_HV
0 0, 1 or V_HV
1 0, 1 or V_HV
Reserved
-
All other encodings
1. The most significant bit, b7, is sent first.
2. Logical Serial Addresses (LSA) are generated by the combination of inputs on the SA pins.
3. For backward compatibility with M34E02 devices, the order of block select bits (b3 and b1) is not a simple binary encoding
of the block number.
4. SA0 pin is driven to Vss, Vcc or VHV.
5. Reading the block protection status results in Ack.
6. Setting the EE page address to 0 selects the lower 256 bytes of EEPROM; setting it to 1 selects the upper 256 bytes of
EEPROM. Subsequent Read EE or Write EE commands operate on the selected EE page.
7. Reading the EE page address results in Ack when the current page is 0, and NoAck when the current page is 1.
Up to eight memory devices can be connected on a single serial bus. Each one is given a
unique 3-bit code on the slave address (SA2, SA1, SA0) inputs. When the device select
code is received, the device only responds if the slave address is the same as the value on
the slave address (SA2, SA1, SA0) inputs.
The 8^th bit is the Read/Write bit (RW). This bit is set to 1 for Read and 0 for Write operations.
If a match occurs on the device select code, the corresponding device gives an
acknowledgment on Serial Data (SDA) during the 9^th bit time. If the device does not match
the device select code, it deselects itself from the bus, and goes into Standby mode.
3.6
Write operations
Following a Start condition, the bus master sends a device select code with the RW bit reset
to 0. The device acknowledges this, as shown in Figure 5, and waits for an address byte.
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