Design Consideration

1.In SAM L22 Xplained Pro the GPIO PC27 is connected to both the LED and the SLCD’s backlight. The LED is configured to be active Low and SLCD’s backlight is configured to be active High. Turning ON the LED shall turn OFF the SLCD’s backlight and vice versa.

2.There is no specific exit condition to return back to the normal state after the tamper occurrence. The user has to define the exit condition in their application as needed.

3.The TAMID flag and the INTFLAG are not cleared by the hardware and has to be taken care of by the firmware. Tamper condition will be detected even when the INTFLAG is set due to previous tamper, is not cleared. The flag has been cleared by the firmware in this application.

4.In the application demonstrated, the device enters into sleep mode after selecting the mode of tamper. The USART will be disabled in sleep mode. After entering a particular mode at least one tamper condition must occur before changing the mode to wake up the device. If tried to change the mode without waking up the device, the terminal window will not reflect the character entered.

5.The RTC time required has to be set by the user manually. Failing to do this shall load the default value of time into RTC clock register. The default time value in 12 hours clock mode:

time.year   = 2000;
time.month  = 1;
time.day    = 1;
time.hour   = 12;
time.minute = 00;
time.second = 00;
time.pm     = false;

6.In this application the RTC clock value will be lost when the device is powered off. On restarting the device, the user must ensure that the current time value is loaded to the device through the application code. The time value can be configured in the firmware as mentioned in the point 2, section RTC Configuration.

7.The NVM controller writes only 128 entries of tamper occurrence to the RWW EEPROM section. If it exceeds the limit the firmware will stop recording the timestamp value in the RWW EEPROM memory section until the user clears the memory.