UM1539 Datasheet, PDF (32/46 Pages) STMicroelectronics – STEVAL-IFS017V1 multi device temperature sensor and RTC demo

Getting started
UM1539
1.2.41
1.2.42
1.2.43
Note:
1.2.44
M41T83_SOX18 RTC timer configuration
1. M41T83 RTC has an 8-bit countdown timer. This timer counts down from the user
configured value (timer countdown value) to 1 and then again reloads the timer
countdown value.
2. Enter any value between 1 and 255 inside the value area of the timer.
3. Select the timer ticking clock from the clock frequency dropdown menu of the timer.
4. Enable the checkbox for the TE bit, this enables the timer. If the TE bit is not enabled,
the timer does not start the counting. The TI/TP bit is used for mode selection of the
timer.
5. The TIE bit is used to output the timer rollover interrupt on the #IRQ1 interrupt pin of
RTC. Whenever the timer rollover occurs, the TF flag is set and the D6 LED glows on
the motherboard. The LED goes off by reading the flag register using the Read Flag
button.
6. Press the Write button to enter the timer configuration values in the timer section of the
M41T83_SOX18 RTC.
7. As soon as the timer rolls over from 1 to the timer countdown value, the timer flag (TF)
is set inside the flag status register of RTC. This flag is cleared only by reading the flag
register. Pressing the Read Flag button shows the status of this flag in the GUI. A
second read clears the flag from the GUI.
M41T83_SOX18 RTC digital calibration configuration
1. Enter the calibration value between 0-31 in the calibration register.
2. Select the positive or negative calibration by selecting the sign in the sign bit dropdown
menu.
3. Press the Write button to configure the RTC calibration register with the selected
settings.
M41T83_SOX18 RTC analog calibration configuration
1. Check the FT bit checkbox.
2. The slider for analog calibration gets enabled and LED D6 glows on the motherboard.
This disables the remaining RTC window.
3. Enter the calibration value using the slider and press the Write button to configure the
value inside RTC.
After the value is configured, remove the check from the FT bit checkbox.
The frequency test function (FT) works only when all the other interrupt functions are
disabled. If any of the interrupt functions are enabled then the frequency test function is
disabled.
M41T83_SOX18 RTC HT bit configuration
At every power-down the HT bit is set. To start the display of the clock on consecutive
powering, the HT bit should be reset each time.
1. HT bit set and reset option is selected from the dropdown menu.
2. Setting the HT bit halts the clock display of RTC.
3. Resetting the HT bit resumes the clock display of RTC.
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Doc ID 023106 Rev 1