sri4k STMicroelectronics, sri4k Datasheet - Page 16

• Manufacturer Part Number: sri4k
• Description: 13.56 Mhz Short-range Contactless Memory Chip With 4096-bit Eeprom And Anticollision Functions
• Manufacturer: STMicroelectronics

Memory mapping
4.2
16/49
Figure 14. WRITE_BLOCK update in Reload mode (binary format)
32-bit binary counters
The two 32-bit binary counters located at block addresses 5 and 6, respectively, are used to
count down from 2
the update of a counter if the new value is lower than the previous one. This feature allows
the application to count down by steps of 1 or more. The initial value in Counter 5 is
FFFF FFFEh and is FFFF FFFFh in Counter 6. When the value displayed is 0000 0000h,
the counter is empty and cannot be reloaded. The counter is updated by issuing the
WRITE_BLOCK command to block address 5 or 6, depending on which counter is to be
updated. The WRITE_BLOCK command writes the new 32-bit value to the counter block
address.
The counter programming cycles are protected by automated antitearing logic. This function
allows the counter value to be protected in case of power down within the programming
cycle. In case of power down, the counter value is not updated and the previous value
continues to be stored.
Figure 15. Binary counter (addresses 5 to 6)
Previous data stored in block
Data to be written
New data stored in block
Block
Address
5
6
Figure 16
MSb
b31
32
shows examples of how the counters operate.
(4096 million) to 0. The SRI4K uses dedicated logic that only allows
b31
b24 b23
1
1
1
...
...
...
1
1
1
32-bit Binary Counter
32-bit Binary Counter
1
1
1
32-bit Block
b16 b15
0
1
1
1
1
1
0
0
0
1
1
1
b8 b7
1
1
1
1
0
0
LSb
b0
1
0
0
1
1
1
Description
Count down
Counter
0
1
1
1
1
1
ai07660
SRI4K
ai07659
1
1
1
b0