EM4069
EM4169
Command 5 : Read configuration word
Read configuration word command is an auxiliary
command used to read configuration word. This mode will
be active until power down or reset command.
The 8-bit CRC with polynomial u + u + u + u + u is
used in commands 3 and 4. The CRC is calculated
including the Command-Byte.
8
4
3
2
0
Write 16 bit EEPROM Word Command
As described in the Command Table an 8-bit pattern has to
be sent to execute commands rst, rROM and rcw. Bit
pattern of Write Word command is different since word
address, 16 bits of data and 8 bit CRC have to be
transmitted. The Write command bit pattern is the
following:
1100 [4 bit word address] [16 bit data] [8 bit CRC]
CRC Calculation
8
U
7 6
MSB
2
U
5
3
U
4
4
U
+
Word address:
One of eight EEPROM words is selected. Valid addresses
are in range from 0 (0000) to 7 (0111)
Data bits:
During read out bit which is first sent in is first read out
(FIFO)
CRC:
Calculated over whole command stream
Example of Write Word command:
C5 D2 2D 20
(hex)
Fig. 9
+
+
3 2 1 0
LSB
+
+ Exclusive OR
Register Stage
Data
The following table shows the CRC according to some test
bytes:
The above command (1100 0101) write to
•
Word 5
•
hexadecimal data “D2 2D”
•
CRC bits are hex 20.
in
Sync.
wr
Byte
[hex]
01
80
Resulting CRC
[hex]
1D
26
out
Read
t
Wee
1ms
Read
In test above it is supposed that the leftmost bit is the MSB
and is transmitted first.
Within 1ms after EEPROM update completion, a further
command will be accepted by the EM4069 without a new
synchronization pattern.
After time-out of this period, the EM4069 will return to read
out mode.
Fig. 10
Write Configuration word Command
Configuration word is a special word which is used to lock
(protect from writing) EEPROM words. The bits of
configuration word are OTP (once programmed at 1 they
can not be reprogrammed to 0).
Special care has to be taken when adding lock bits to
the protection word that already has some bits set to
one. The bits that are already set to one have to be
confirmed at a new command in order to allow writing
of additional bits. If not, bits that are already locked
stay locked, and the new selected bits might not be
programmed.
Copyright
2003, EM Microelectronic-Marin SA
8
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EMMICRO [ EM MICROELECTRONIC - MARIN SA ]
