ATmega328P Power saving

Other Hardware 3rd Party Boards
1

Hi, I am hoping this is a straightforward question. I am setting up a 433Mhz remote transmitter based on the Atmega328 chip. I am trying to minimise the power consumption so am using a watchdog timer. I have read that reducing the VCC reduces the power. I am confused though as at 5v I get 30mA running the sensors and 0.59mA sleeping but at 3.3v its 15mA running and 1.8mA sleeping although initially after booting it uses 0.26mA but after a loop though the sensor readings it settles at 1.8. I had really wanted to get to 100uA but 250 would do.
I am trying to think how to trouble shoot this. There is only a DS3231RTC and a Y401 ultrasonic sensor. Both are switched though a transistor. The watchdog it set to 8 seconds and just loops though for 10 times whilst testing.

Thanks

2

Is the 328p on a custom board or official/clone hardware?

3

It's a bare chip on a breadboard with external oscillator.

4

Unless you need it, you can ditch the external oscillator and go with the internal one.

You should also post your schematic and your code.

5

Could be a problem with your code or the way the hardware is all connected.

6

If you can run it at 4MHz, then you can power the whole thing with a couple of AA cells. If anything needs a higher voltage, you can switch on a boost converter. I have an ATmega328p project here which does that and, in sleep mode, I get into the low microamps: Arduino NRF24L01 Mailbox Monitor/Notifier - Exhibition / Gallery - Arduino Forum

7

Thanks all for the comments and in particular 6V6gt for his project details, which I may use bits of.
I have rewitten the code a bit and added an extra couple of 1uF caps and new MCP1705 regulator and that has fixed the problem. I am now down to 100uA, which is getting more like a battery project.

8

An ATMega328 when used with an MCP1700 regulator, and using the watchdog timer as wakeup, will consume around 8uA when in sleep mode.

For an example see here;

Still running after 13.5 months from a 155mAhr battery.

9

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