Making Arduino sleep when Idle and wakeup when a sensor goes high

Projects Programming
1

Good Day guys! I need some help on my project specifically RFID.

To save battery, I want my RFID system to go to sleep when it is not reading a card but wakes up when a card gets near to it.

There are three pins on my RFID, TX(output), RX(input), LED(input).

I notice that when it is reading a card the LED pin is LOW and when It is not reading it is HIGH.
So basically what I want is for my system to go to sleep when the LED pin reads HIGH for lets say 10 secs.
Then the moment it reads a LOW, arduino wakes up.

Any sample program is much appreciated so I can incorporate it in my code.
Thank a lot and more power to out COmmunity! :smiley:

2

Is it going to be OK to leave the RFID receiver powered up continuously?

You can use a LOW level on Pin 2 (interrupt 0) or Pin 3 (interrupt 1) to wake up a sleeping ATmega.

If the reader draws significant power you might want to wake up every second or sow using the watchdog timer. Then you can power up the RFID reader and check for data. With some experimenting you can determine how long you have to leave the reader powered up to receive a signal if a card is in range.