Power saving; it's an art form. I'm stumped.

Community Chit Chat
1

I am creating a device based on a ATtiny85 MCU that will be powered by a coin cel battery that I wish to last for many months. The work the device is expected to do is to wake up when a pot value changes, transmit (by nRF24l01) the analog value sensed from the pot, and then go back to sleep.

The schematic I have in mind has a pot with pin1 at ground pin2 as sweeper to the ATtiny, and pin 3 at VCC to ground, basically a 10k load from vcc to ground is a predictable way to reduce battery life. I can raise the value of the pot to make it drain the battery slower, but the higher the impedance the more it will be effected by RFI/EMI causing false triggering, waking the radio, etc… killing the battery.

Is there some sort of extremely low powered comparator I can use to wake the MCU? Or perhaps ditch the ATtiny for a MCU with more pins so I can use the internal comparator (if “wake on internal comparator” is such a thing ).

Thanks for any input,

Dan

San Jose, CA

2

I would have the micro sleep and wake up periodically. When it wakes up, it would turn on power to the pot (you could use a GPIO to provide this), read the value, and turn off the pot. If the value has changed, wake or power up the radio, send the message, turn off the radio, and go back to sleep.

0.3mA continuously will drain that battery quickly

/mike