EM4069
EM4169
Command 5 : Read configuration word
Write 16 bit EEPROM Word Command
Read configuration word command is an auxiliary
command used to read configuration word. This mode will
be active until power down or reset 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:
The 8-bit CRC with polynomial u8 + u4 + u3 + u2 + u0 is
used in commands 3 and 4. The CRC is calculated
including the Command-Byte.
1100 [4 bit word address] [16 bit data] [8 bit CRC]
CRC Calculation
Word address:
One of eight EEPROM words is selected. Valid addresses
are in range from 0 (0000) to 7 (0111)
8
2
3
4
U
U
U
U
Data bits:
During read out bit which is first sent in is first read out
(FIFO)
7
MSB
6
5
4
3 2 1 0
+
+
+
+
LSB
CRC:
Calculated over whole command stream
Data
+
Exclusive OR
Register Stage
Example of Write Word command:
C5 D2 2D 20 (hex)
The above command (1100 0101) write to
•
•
•
Word 5
Fig. 9
hexadecimal data “D2 2D”
CRC bits are hex 20.
The following table shows the CRC according to some test
bytes:
in
Sync. wr
Read
Byte
[hex]
01
Resulting CRC
[hex]
1D
out
Read
80
26
tWee
1ms
Fig. 10
In test above it is supposed that the leftmost bit is the MSB
and is transmitted first.
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).
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.
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.
8
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