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Questions tagged [rtc]

Real-Time Clock. Keeps track of current date/time. Some have batteries like the DS3231, and the DS3231 also has programmable alarms that can interrupt an Arduino.

Real-Time Clock. Keeps track of current date/time. Some have batteries like the DS3231, and the DS3231 also has programmable alarms that can interrupt an Arduino.

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Convert to and from Unix Timestamp

What is the best way to convert between date, hours, min, seconds to Unix timestamp in milliseconds in Arduino? I need to have this conversion, since I'm using RTC (date, hours, min, secs etc) and communicating Unix timestamp over BLE I found some…
Dzung Nguyen
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The difference between "time_t" and "DateTime"

I've run into an issue trying to combine 2 different Arduino timer projects I've found online. For both projects I'm using a DS3231 RTC, but have been able use the DS1307 library just fine in my code. The first set of code I picked up started…
Vinterwoo
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ESP32 how to preserve RTC time during brownout

I want to use the ESP32 built-in RTC clock. In my situation, my ESP32 will not have access to an NTP server I do not want to use external RTC modules ESP32 provides a pin VDD_RTC will powers the RTC domain exclusively My problem would be solved if I…
mquevedob
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Calculate absolute time based on cycles and RTC

I'm developing a low power data logging device. It samples sensors at the frequency of 20Hz, and also has a real time clock for absolute time (the logged time need to be exact down to ms). I think that querying time for every samples would be…
Dzung Nguyen
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DS1307RTC Outputting cryptic 165/165/2165 date. What are some possible fixes?

My board. I think I have it wired correctly (the lights aren't, but the board is). I've read through the first few Google results to no avail. My sample code to test the chip: // Date and time functions using a DS1307 RTC connected via I2C and…
Rashi Abramson
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RTC resets when power is off

I have a few RTC modules with a batteries. All of them have this same issue with my project. They work fine when connected via USB. But if I disconnect the power then reconnect they reset to Jan 1 2000. I've read several posts about similar…
futurebird
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RTC interrupts and coin batteries

Summary I'm having problems with my RTC draining its coin cells quickly - fresh batteries are drained in a few months. The RTC is set to signal an interrupt every 5 minutes, and I wonder - if there is no other power attached to the circuit, is that…
Tyler
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Nextion Display not getting updated data

I am using an Arduino Mega to display the readings of 4 pots on a Nextion Display as well as store them on an SD Card with a time stamp. I keep getting: recvRetCommandFinished err on the serial monitor and the display does not update with time. I…
Niteesh Shanbog
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Set control register to low in ds3231 rtc

I have been using ds3231 rtc module for keep tracking and make alarm along with backup battery. when I used it for first time it worked fine. but now it doesn't keep track my time when the power lose it from main power but I have checked that my…
Sharifdeen Ashshak
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How to wake up Arduino with an rtc?

I am doing a data logger with an Arduino Mega2560 and I want to use a code to make it sleep when no measure is needed and wake it up with an RTC when time comes. The reason I want this is because I intend to run the code on a Pro Mini later so I…
JamesONeil
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Scheduling and BLE Read on demand

I'm building a data logging device with BLE capability using RFduino. Sensors are read using timer interrupt to a buffer. When the buffer is full, then the whole buffer is written to SD card. At the same time, I have BLE_Receive to set time of the…
Dzung Nguyen
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How to have some code executed at a certain time of day with a DS3231 RTC?

I recently bought a DS3231 RTC, but I cannot seem to figure out how to get it to work. I have tried all different tutorials and example programs but I keep getting 2165.25.165 165:165:165 as the output. I am using an Arduino Micro, with the RTC…
Zelkins
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How to set Alarms on the DS3231 easily so the Nano doesn't have to go to sleep with delay statements?

I want my solar array sun tracker to shut down at night then move full east in the morning to catch the first rays. I know the DS3231 can set alarms but it is not clear from its documentation how to do it with the normal library. Delay…
SDsolar
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Comparing time_t values within an if statement

I am using an UNO with a RTC to control a light board. I'm using a simple control structure to decide when to turn things off and on. It's my understanding that a time_t value is just a number (number of seconds since 1970), and that I should be…
Vinterwoo
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How to improve date-time control from RTC?

I want to run cameras at a remote site from external batteries as long as possible. I need power-miser Arduino to switch battery power on/off at set intervals (e.g. 5 min) during daytime only. I am a beginner with Arduino and electronics. Have set…
jules
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