user88667: Whilst I am much more at home programming PIC ISR's in assembler, I am building a data logger using a DS1307 to interrupt every second to write data to a USB SD card.
There does not appear to be a connection or even a pad from the DS1307 SQW for interrupts and feel I must be missing something, as this would be a remarkable designer/manufacturer oversight?

user70020: I can't find any official source for information about "Deek-Robot datalogging shield" but what I do find indicates it is the same or similar design as an Adafruit Datalogging shield. The DS1307 (or other RTC) square wave out signal is routed to a through-hole on the interior of the board indicated in this image:

It does not appear to be routed anywhere else an any of these boards. Note: the picture here is of a board (Current Adafruit logging shield apparently) that uses an NXP RTC that has the same pinout as the DS1307, but uses a different register layout. But in any case places the SQ output on a header in the same basic location. So you would need to solder a header to accept a jumper. Or solder a wire from there to one of the through holes for a digital pin, probably pin 2 or 3 if you're on an UNO (you have tagged) since those are the pins compatible with attachInterrupt()

88667: <p>Whilst I am much more at home programming PIC ISR's in assembler, I am building a data logger using a DS1307 to interrupt every second to write data to a USB SD card.</p>
<p>There does not appear to be a connection or even a pad from the DS1307 SQW for interrupts and feel I must be missing something, as this would be a remarkable designer/manufacturer oversight?</p>
 70020: <p>I can't find any official source for information about &quot;Deek-Robot datalogging shield&quot; but what I do find indicates it is the same or similar design as an <a href="https://learn.adafruit.com/adafruit-data-logger-shield/" rel="nofollow noreferrer">Adafruit Datalogging shield</a>. The DS1307 (or other RTC) square wave out signal is routed to a through-hole on the interior of the board indicated in this image:</p>
<p><a href="https://i.stack.imgur.com/qRqkO.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/qRqkO.jpg" alt="SQ pin indicated" /></a></p>
<p>It does not appear to be routed anywhere else an any of these boards. Note: the picture here is of a board (Current Adafruit logging shield apparently) that uses an NXP RTC that has the same pinout as the DS1307, but uses a different register layout. But in any case places the SQ output on a header in the same basic location. So you would need to solder a header to accept a jumper. Or solder a wire from there to one of the through holes for a digital pin, probably pin 2 or 3 if you're on an UNO (you have tagged) since those are the pins compatible with <code>attachInterrupt()</code></p>
