Hi,
I am using Rocket Screams Mini Ultra 8Hz (Arduino Pro Mini 8Hz 3.3V compatible). When I run the example code provided with the DS3234 RTC, my onboard LED (pin 13) turns on when I call rtc.update(); I have tried setting 13 to output and digitalWrite(LOW) but it is still on. My setup is exactly as shown in the hookup guide.
Any ideas how why this may be happening?
Thanks,
Jeremy
Hi Jeremy.
The LED on D13 is connected to the SPI bus and whenever you’re transferring data over the bus, D13 goes high and low automatically. That’s what’s causing the LED to light up. You really can’t stop this behavior without removing the LED from your Arduino. It’s normal and nothing to worry about. 
Gah! Except for power consumption! It is costing me about .6mA, which is a lot for my application.
Thank you Chris for the quick response!