My application is now running fine with an ATMega328P that measures sensor values regularly and is interrupted each minute by a DS3231 Real Time Clock using the library of Makuna:
For the low power mode, I am using the library of rocket scream.
Similar to what is shown in this diagram:
I have hooked up the RTC to the 3.3V output of the Arduino (not 5V). During sleep mode, the power of the Arduino drastically decreases but the LED of the RTC is still blinking.
Is it ok to just desolder/cut/destroy the LEDs on the RTC board?
Can I reduce the power consumption by programming such as disabling the 32kHz output, as shown here: https://forums.adafruit.com/viewtopic.php?t=45933
Is there eventually another RTC with good Arduino library support and a package that is large enough to allow for prototyping?
Is it ok to just desolder/cut/destroy the LEDs on the RTC board?
Can I reduce the power consumption by programming such as disabling the 32kHz output, as shown here:
As you failed to provide a link to the hardware you're using (to the schematics of that DS3231 board) we cannot tell you. The DS3231 is capable of running very low power but an RTC board with LEDs on it is definitely the wrong choice if you plan to run this on batteries.
If you search google, there are whole webpages on running an RTC at low power. Its possible to power the RTC solely by its own backup battery, except for when you need to write data to its registers, and at that point provide power from an arduino output port.
pylon:
As you failed to provide a link to the hardware you're using (to the schematics of that DS3231 board) we cannot tell you. The DS3231 is capable of running very low power but an RTC board with LEDs on it is definitely the wrong choice if you plan to run this on batteries.
I'd like to power it from my own battery that is rechargeable since the DS3231 should be operationable for more than than one year.
david_2018:
If you search google, there are whole webpages on running an RTC at low power. Its possible to power the RTC solely by its own backup battery, except for when you need to write data to its registers, and at that point provide power from an arduino output port.
Thank you for that information! Anyways, I'd still like to use my own battery connected to VCC and GND to power the module and not use the provided battery. Eventually, I can also use the pins of the battery holder and check the acceptable voltage inputs. It might be ok to power it with 3.7V LiPo or eventually I use a Low Dropout Voltage Regular.
I haven't found much online for configuring the DS3231 for low power consumption using an ATMEGA328P. Could you please forward me the links?
Is it ok to just desolder/cut/destroy the LEDs on the RTC board?
Yes.
I'd like to power it from my own battery that is rechargeable since the DS3231 should be operationable for more than than one year.
I understand that so that you want to replace the CR2032 with your own battery. That is not a good idea in most situations. The CR2032 will last more than a year under normal circumstances.
Can I reduce the power consumption by programming such as disabling the 32kHz output, as shown here:
You can but it probably won't be that relevant.
Do you need that on-board I2C-EEPROM? If not it might be a good idea to cut it's power.
I have hooked up the RTC to the 3.3V output of the Arduino (not 5V).
Why 3V3? It might be a good idea to desolder the 3V3 voltage regulator as it draws quite a lot current.
Are you using an Arduino or a custom ATmega328p board?
Anyways, I'd still like to use my own battery connected to VCC and GND to power the module and not use the provided battery. Eventually, I can also use the pins of the battery holder and check the acceptable voltage inputs. It might be ok to power it with 3.7V LiPo or eventually I use a Low Dropout Voltage Regular.
What advantage do you see in this setup? I would use the provided battery for the backup of the time keeping oscillator and use the LiPo to power the CPU.
I haven't found much online for configuring the DS3231 for low power consumption using an ATMEGA328P. Could you please forward me the links?
Post the schematics of your ATmega328p board. You can probably save much more power on that board than on the RTC board (except desoldering the EEPROM chip).
This page describes useful modifications to the correct the terrible design problems with your DS3231 module.
Be sure to disable the LIR2032 charge circuitry before using a CR2032 battery.
One way to use the DS3231 module in extremely low power mode is to have it interrupt the ATmega328 at intervals, using the *INT/SQ or the 32K output. To make that work, you must have a pullup resistor from the ATmega Vcc to the interrupt input, and remove the pullup resistors on the DS3231 board, as described in the link above.