UM1539 datasheet(24/46 Pages) STMICROELECTRONICS

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Getting started

UM1539

24/46

Doc ID 023106 Rev 1

1.2.19

M41T82 RTC date and time setting

Click on the RTC selection icon in the toolbar of the GUI. RTC selection Radio button

appears in the GUI, as shown in Figure 15.

Select for RTC M41T82, it opens the RTC GUI window for the M41T82, as shown in

Figure 16.

Press the Update button to enable the configuration of RTC. Pressing the Update

button enables the GUI window for RTC configuration. It also reads the RTC registers

and displays the same in the GUI.

After pressing the Update button, reset the HT bit to see the clock ticking on the display.

Configure the RTC date and time by clicking on the Set Time button in the GUI. It

programs the onboard RTC with the system date and time.

CB0, CB1, Stop bit, and OFIE bit are checkboxes to enable or disable the respective bit

in RTC. Checking the box and then pressing the Write button sets the bits and un-

checking them and clicking on the Write button resets the bits.

The Program button configures the RTC with the current settings visible in the GUI.

The RTC Reg button shows the RTC registers and the values present in those

registers.

Device time in the GUI also reads the milliseconds from RTC and displays them in the

GUI.

1.2.20

M41T82 RTC alarm setting

M41T82 RTC has two alarm functions:

●

Alarm one

●

Alarm two

Alarm one

Set the alarm date and time using the alarm one date and time section of the RTC GUI

window.

There is no alarm output pin in M41T82 RTC. As the alarm time is matched, the AF1

flag is set inside the flag status register. This can be seen in the GUI by pressing the

Read Flags button.

The alarm status can be seen in the GUI by pressing the Read Flags button. Pressing

this button again clears the alarm register of RTC and its new status is shown in the

GUI.

The Reset OF button is used to reset the OF bit in the alarm register and,

correspondingly, the oscillator bit alarm is also cleared by resetting the OF button.

Alarm two:

Set the alarm date and time using the alarm two date and time section of the RTC GUI

window.

Checking the AL2E bit and writing it using the Write button enables this alarm. On the

matching of the RTC clock time and date with the alarm two time and date, the AF2 flag

is set inside the flag status register.

Alarm status can be seen in the GUI by pressing the Read Flags button. Pressing the

read flags again clears the alarm register of RTC and its new status is shown in the

GUI.

The Reset OF button is used to reset the OF bit in the alarm register and,

correspondingly, the oscillator bit alarm is also cleared by the Reset button.

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