Velleman KA07, Manual, Page: 8 / 12

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General information
General information
II
Back-up battery: provides power to the shield when the Arduino Uno
is not active
.
Place jumpers JP2 and JP3 when using the shield with the Arduino
Uno rev2 or Arduino 2009.
The IC drives an LED, which blinks at the same frequency as the
SQW output. Select via jumper JP1 whether this signal goes to pin
A3 of the shield.
The library allows you to manage the
frequency of the LED. Use command
RTC.sqw(x). Values for ‘x’:
0: LED off
1: 1 Hz
2: 4096 Hz
3: 8192 Hz
4: 32768 Hz
Download the library from www.vellemanprojects.eu.