EM4205-EM4305
Commands
Command code structure:
All commands start by 3 bit command code, followed by command arguments. Possible command arguments are a word
address and a 32 bit data field.
The 3 bit command code is terminated by an even parity bit:
cc0
cc1
cc2
P
Table 11.a
Address structure:
The address field contains 4 bit address, two bits at 0 reserved for future use and an even parity bit.
A0
A1
A2
A3
"0"
"0"
P
Table 11.b
Data structure:
The 32 bit data field has an even parity bit inserted every 8 data bits, data is terminated with 8 column parity bits and a 0.
Figure 11 represents the organization of command fields.
D0
D8
D16
D24
PC0
D1
D9
D17
D25
PC1
D2
D10
D18
D26
PC2
D3
D11
D19
D27
PC3
D4
D12
D20
D28
PC4
D5
D13
D21
D29
PC5
D6
D14
D22
D30
PC6
D7
D15
D23
D31
PC7
P0
P1
P2
P3
"0"
Table 12
There are five commands implemented: Login,
Write Word, Read Word, Protect and Disable.
When the Login command is successfully processed, the
IC responds with preamble pattern (00001010) and returns
to Default Read mode.
When the Login is not accepted (wrong password or error
in parity) error pattern 00000001 is sent and the IC returns
to Default Read mode.
Command
Login
cc0 – cc2
001
P
1
1
1
0
0
010
Write Word
Read Word
Protect
100
Write Word Command
110
In Write Word command the 4-bit word address is first
sent followed by 32 bit data encoded according to the
structure described in tables 11 and 12. During a write
word sequence, it is recommended to place the
EM4205/4305 in strong field conditions to ensure a
correct EEPROM writing. In the case that the command
is correctly processed, the EM4205/4305 checks whether
the addressed word is not write protected or there is no
parity error. It then checks if there is enough power
available to program the EEPROM (Power check). In the
case that all these conditions are fulfilled the EEPROM is
written. After the EEPROM is written, the Configuration
word is reloaded from the EEPROM, a preamble pattern
(00001010) is sent and the chip returns to Default Read
mode.
101
Disable
Figure 11
Upon successful decoding of first field stop followed by a logic
“0” bit, the chip starts command decoding. In case command
code is not corresponding to one of the four possibilities or parity
bit is wrong command processing is interrupted and default read
is resumed.
Login Command
Sending the Login command is necessary before
sending any password protected command. In the Login
command a 32 bit password including parity bits is sent
as the command argument. The 32 bit password is sent
according to the Data structure defined in table 12 (45
bits including parity). When the parity bits are correct and
32 bit password sent matches the content of Word 2, the
login flag is set.
Loading of Configuration word is useful when the
Configuration word has just been changed so that new
settings are loaded.
Login flag is set until the next power-up, which means
that Login command has to be sent only once after
power up to enable execution of password protected
commands.
If the Write Word command is not accepted (error in
parity or at least one of the checks failed) error pattern
00000001 is sent and the IC returns to Default Read
mode.
Read Word Command
In Read Word command the 4-bit word address is sent
as command argument according to the structure
described in table 11. When the command is correctly
processed, a preamble pattern (00001010) followed by
the content of the 32 bit word is sent. Please, note that
the 32 bit data is sent using the command data structure
10
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Copyright 2013, EM Microelectronic-Marin SA
4205-4305-DS-01.doc, Version 4.0, 22-Oct-13
EMMICRO [ EM MICROELECTRONIC - MARIN SA ]
