Teensy 3.2 + RTC wake up on specific time

[zstergios]

I have purchased the teensy 3.2 and I will got it tomorrow.

I will move on from Arduino Pro Mini V3.3 to Teensy because of FLASH & RAM.

On Arduino I used DS3231 and with this Library https://github.com/sleemanj/DS3231_Simple I wakeup (setAlarm) the arduino for example at 21:00 every day.
With that way I save a lot of energy and I have accuracy (send SMS)

Seems, with some research that I have done, there is not way to use Teensy's RTC (adding crystal) to wake up on exact HOUR-MINUTE.

Seems more complicated to me...I'm trying to understand HOW to SLEEP and WAKE with external interrupt
https://forum.pjrc.com/threads/33243-RTC-alarm-to-wake-up-from-deep-sleep

My project has
DS3231
SIM800L
DHT22x2
HX711

So I would like to tell/help me the best possible solution
1) Iron a crystal + CR2032 v3 bat
2) Use DS3231 with Library "DS3231_Simple"
3) other....(?)

THANK YOU FOR YOUR TIME!

 

[WMXZ]

if you need features of DS3231 use it with SW of your choice.
AFAIK, wakeup can be from external interrupt

 

[tni]

Look at the Snooze library. You can configure wakeup sources. Both digital pins (interrupt from DS3231) and the internal RTC work:
https://github.com/duff2013/Snooze/...bernate_all_wakeups/hibernate_all_wakeups.ino

Make sure to include 'alarm' in the SnoozeBlock, if you use the internal RTC.

Depending on the sleep mode, not all digital pins work as wakeup sources. the Snooze sketch has a comment with the pins that work in hibernate mode.

BTW, Teensy 3.5 and 3.6 come with RTC crystal included.