ds3231 | arduino library for DS3231 RTC

I'm working on a ASUS TinkerBoard, OS Linaro 9.5 - Kernel 4.4.132

I added a little RTC board based on DS3231 chip.
The system creates the device /dev/rtc1 added to /dev/rtc0 and /dev/rtc (link to /dev/rtc0).
I'm able to talk with the RTC chip via i2cdetect and hwclock commands but I have a strange behavior.

This is my tests - of course I'm disconnected from the network to avoid the ntp sync:

WITHOUT RTC: at every power up the board/OS resets the date and time from Nov 03 2016 00:00

WITH RTC:

• synced the date/time by Internet connection
• forced the RTC value set by hwclock -f /dev/rtc1 --systohc
• checked the value by 'hwclock -f /dev/rtc1 --get'
• disconnected from the network and powered down the board - let's say at 18:00
• powered up the board at 18:15
• when the desktop is ready I see the system time is set to 18:00 (?)
• if I read the RTC by hwclock -f /dev/rtc1 --get and I have 18:15
• the data is correctly set to today (!)

It seems the system date is restored, the system time is freezed at the power down time, the RTC time is correct but it is not restored to the system time.

Any idea?

I have written a bluez application on Raspbian Buster, Raspberry Pi 4. In some reboots, the bluetooth module and service are not loaded.

On checking the bluetooth.service with command: $ sudo systemctl status bluetooth.service, I see, Condition check resulted in Bluetooth service being skipped.

I checked $ lsmod and $ dmesg logs for both issue and non-issue conditions.

The difference I find in the lsmod is shown below:

The difference I find in the dmesg log is shown below:

The left side is the issue case and the right side is non issue case.

How can I fix the issue so that the bluetooth works consistently? I am using Raspbian Lite OS 2020-02-14.

Update 1 [03 Feb 2021]: I checked the journalctl log for the issue case and found this:

I'm currently trying to measure remaining time until a given timestamp using Adafruit's RTClib library. My RTC module is a DS3231. here is my TimeSpan object in code:

My intention is a program a system that turns on at a certain time and also turns off at a particular time. But the problem I'm facing is that each time it gets to the scheduled time to turn on the sensor starts sensing motion even when there's no motion for a few seconds after that it goes back to normal. Normal in the sense that it stops sensing motion when there's no motion. I ran a basic motion dection code using PIR sensor and led just to check if the sensor is working properly, it worked out fine so I don't really know why I'm still getting that error. Please how can I eliminate this error cus I have very little knowledge on how to program an Arduino.

This code is meant to be useful for detecting an intruder at a particular time interval, then it turns on 2 led's and a buzzer and then send a text message to the pre-programmed number. But the challenge I'm facing is that when the system comes on the pir sensor keeps sending a logic 1 and that in turn makes the gsm module to keep sending text message even when no intruder is in range also immediately the scheduled time elapses the sensor then again sends a logic 1 before finally going off. Secondly the text message I receive shows Content not support. Please I'm really in need of help I'm confused and I don't know what to do anymore.

i am having a bit of trouble understanding why the "while" loop in my code doesn't stop when the condition is met.

I want to use a DS3231 RTC (ZS-042) to make precise time measurements on my arduino uno. I need to measure milliseconds, to the regular time functions of the various RTC libs are not enought.

After googling & asking aroung I found that I need to use the SQW output of the DS3231 and attach it to an interrupt or timer. When using the appropriate rate, I would be able to perform time measurements.

So I tried wiring the SQW to pin 5 on my arduino uno (which is the T1 input), and configure T1 to use an external source. I used some RTC lib to enable the SQW output and set it to 1024hz. Then I attached the ISR for counting ticks and overflows.

All this seems to basically work, however the SQW signal seems to be stuck at 1hz, no matter what I do.

Here is my code:

I am trying to synch the hour between localtime and RTC. I have DS3231 RTC, i followed a guide to install and configure the OS to use it, RTC is working, but the time without internet is 2 hours backwards. My timezone is GMT+2 and its set correctly in /etc/localtime. When NTP is working everything is looking fine. Output of timedatectl:

I have a Raspberry Pi 3B and Suptronics X920 Expansion Board which uses PCM5122 DAC. So I'm having trouble playing sounds through that board.

The config file is default except for the display configuration part: