Arduino standby deep sleep mode with 7 segment 4 digit display and touch sensors

Hello,

I currently have a 7 segment 4 digit display working in unison with a RTC 1307 chip to display the time. I however require my project to be sustainable and have it run off batteries which are powered via a renewable energy source.

So while browsing through forums, I have come across a deep sleep mode for the Arduino and was thinking of having my display on sleep mode until someone triggers a capacitive touch sensor to wake the arduino from sleep and light up my display again showing the appropriate time. (I am using a RTC chip not a RTC module so I am foreseeing some errors in showing the appropriate time since I do not have the CR2032 battery with me at the moment)

I was just oblivious yet curious as to how I was going to implement the above into my code as I am fairly new to programming with Arduino.

Any tips or help would be greatly appreciated!

Do you have a capacitive touch sensor for that? You cannot use an Arduino sketch to get one because while the Arduino sleeps it cannot check that sensor.

Without a battery backup for your RTC your project won't work as it will loose the time if the power supply fails.

OK, that's fine, the shutdown current of the MAX7219 is only 150 μA, but what sort of Arduino do you propose to use?

You need a (modified) Pro Mini for battery operation as a Nano has a USB interface chip drawing current even if you sleep the 328.

Paul__B:
OK, that's fine, the shutdown current of the MAX7219 is only 150 μA, but what sort of Arduino do you propose to use?

You need a (modified) Pro Mini for battery operation as a Nano has a USB interface chip drawing current even if you sleep the 328.

Ah thats very useful information as i transitioned from the Pro mini for that specific reason...

I was considering using an ESP32S sparkfun board to handle the display as well as the RTC module.

pylon:
Do you have a capacitive touch sensor for that? You cannot use an Arduino sketch to get one because while the Arduino sleeps it cannot check that sensor.

Without a battery backup for your RTC your project won't work as it will loose the time if the power supply fails.

Oh I have the battery backup and cap touch sensors at the moment. I just wasnt sure as to how I was going to program my ESP32s on the IDE to be in sleep mode after being on for a minute and "wake it" with a cap touch sensor to display the time with minimal error.

If that's an LCD type display, you can run your project off a CR2032 for a very long time - without recharges.

The problem is the touch sensor, don't know know how to possibly wake up an Arduino with that. Maybe some additional circuitry can be used to create a useful signal?

By the way, do get a somewhat more modern RTC, as many have much lower power consumption than the old DS1307. Significant savings are to be had there, and better time accuracy in the process.

wvmarle:
If that’s an LCD type display, you can run your project off a CR2032 for a very long time - without recharges.

The problem is the touch sensor, don’t know know how to possibly wake up an Arduino with that. Maybe some additional circuitry can be used to create a useful signal?

By the way, do get a somewhat more modern RTC, as many have much lower power consumption than the old DS1307. Significant savings are to be had there, and better time accuracy in the process.

My display is a custom large led display i made myself with a pcb and a few a components:

I am going to be powering the entire project from a lipo battery connected to a large solar panel. The circuitry is going to be placed behind a thin layer of bamboo wood with the cap touch sensors being part of the circuitry.

Thank you for the tip about the RTC IC! @wvmarle

PCB_6 segment sunstation PCB_20200224153524.pdf (1.01 MB)