Infineon SPI F-RAM FM33256B, Руководство пользователя

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Application Note 7 of 19 001-87564 Rev.*D
2021-06-01
A Design Guide to SPI F- RAM™ Processor Companion - FM33256B
Processor Companion Features
r e s t r i c t e d
Note: In polled mode, the CNT pin has an internal pull-up resistor and therefore no external pull-up is
required.
A typical application in Figure 2 shows a normally-closed switch connected between the CNT pin and ground
(or a system case or chassis). The CNT pin is set to polled mode, which occasionally samples the pin in order to
minimize the battery drain. There are no external resistors required for this case. The event counter is
configured to detect a rising edge (CP = 1, register 0Dh, bit 0) on the CNT pin. When the switch is open, a tamper
event is registered and the counter increments.
4.4 Serial Number
The F-RAM processor companion provides a 64-bit lockable serial number (register 10h to register 17h in
Figure 4 ). The serial number provides a unique way of identifying each product. The serial number has
unlimited writes until the lock-bit is set by the user.