Today I got the first battery operated prototype running. The ATMega and the radio are now in power down most of the time and the micro is awaken with a watchdog interrupt every 8 seconds. The watchdog uses the internal 128KHz oscillator, so the power consumption is much reduced during sleep. From first tests waking the radio, doing the required business to send a message and put everything back to sleep takes about 100mS, which gives a sleep to awake ratio of about 80/1. The test started at 21:00 of November 21st, let’s see what can we get from two CR2032. There is surely a lot to be still optimized, but this will serve as a baseline for future improvement.
Testing low power modes