rtc ds1307 1 minute wake up

My sketch last a few second so the 1Hz ds1307 pulse is not useful for me. I found a solution that I suppose most of you will consider rough. I hope it will be useful for anyone. This is my rtc: http://snootlab.com/shields-snootlab/86-memoire-fr.html

I loaded the sleep sketch example form here: http://playground.arduino.cc/Learning/arduinoSleepCode

I unmount a R10 V10 diode from a broken power supply and added a 100nF capacitor and I connected them between a dig pin (pinout mode) and the pin 2 (low). I didn't found the datasheet of the capacitor but i measured the resistance: 0.77Mohm and 73Mohm inverting the pole. I suppose it is similar to A10 V10 diode. Two mseconds are enough to charge the capacitor. It also works connected to a pin used for other purpose. The high resistance of the diode makes dicharge the capacitor, just to the same pin (pinout mode) that charged it, in about 50 seconds. A little delay may be added to comparing time of ds1307. I tried to substitute the diode with a led diode but the capacitor time discharge varied continuosly.

dig pin--------diode----------capacitor----------pin2 (I didn't manage to insert the fritzing image)

what is your goal? do you want your sketch to sleep for a minute? have a look at the narcoleptic library - https://code.google.com/p/narcoleptic/downloads/list -