For every 15 minutes once ultrasonic sensor data will be send to the receiver using nRF24L01. I'm using atmega328P with battery power using AAA*3 battery and it should operate at least 15 days. Can someone please suggest me how to reduce power consumption, except the time of reading data from sensor. I referred number of blog, they using deep sleep mode, but I need to wake up it for every 15 minutes. I can't use watchdog timer since its has only 8 seconds. If I use external RTC for interrupt it added cost in product.
Thank you in advance :)