Questions regarding Real Time Clocks (RTCs) which can be a timekeeper IC used by microcontrollers, or using a microcontroller as an accurate timekeeper. Some have calendar, alarm, interrupt or heartbeat features, while some simply keep track of time since last programmed (Epoch timers are similar).

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PIC18F2550 and DS1307 i2c RTC MPLAB assembly code. Have to loop for seconds,mins,hrs

PIC18F2550 and DS1307 i2c RTC MPLAB assembly code. I am using a PIC18f2550 to get time,date,etc from DS1307. I am able to get the seconds,minutes, hours, etc by repeatly CALLing GET_TIME with ...
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2answers
99 views

Implementing a low cost battery backup circuit for internal RTC in STM32F030R8

Extension of this question. Datasheet: http://www.st.com/resource/en/datasheet/stm32f030f4.pdf The micro-controller in question has an internal RTC module but no VBAT pin. As such, the only way RTC ...
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3answers
104 views

RTC - is it worth it? [closed]

I need to design a circuit which will count the number of incoming impulses from an external source (the signal`s frequency goes from about 0.05 Hz to maximum 100 Hz) in a preset time interval (that ...
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2answers
122 views

4x4mm QFN-16 to 3x3mm QFN-16?

Ok, so I goofed... accidentally spec'd a 4mm footprint for a 3mm real-time-clock-calendar IC. Rather than scrap these boards, I'm thinking of designing a double-sided PCB "adapter" to go from the ...
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2answers
65 views

RTC Battery Voltage Error; Non-Ideal Op Amp Error?

First post here from a hobbyist electronics guy so please bear with me. I'm happy to do whatever I can to improve my question for the community. For a bit of a backstory, I have a project that ...
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1answer
85 views

What are all these pins on the DS1307 RTC for?

I recently ordered a DS1307 RTC from ebay. Before, I did some research and found out that you only need 4 pins for it: Vcc, GND, SDA, and SCL. The one I got has many other pins like DS, BAT, SQ(I read ...
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3answers
125 views

Using the ST-LINK Utility to configure the RTC to current time

What I was doing I am using a STM32 microcontroller and for my project I need to be able to send data at specific times of the day (say, at 11am and 2pm). The microcontroller needs to know what time ...
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1answer
53 views

STM32 Backup registers stability

I'm using backup domain of stm32 for storing date and some important information. The board drives a thermal printer and some other parts that produce interference on power. It seems that sometimes it ...
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1answer
67 views

RTC in MSP430 microcontroller

I'm trying to generate a 15 minutes alarm using RTC in MSP430F5438A microcontroller from Texas Instruments. What values should I put in the Interrupt registers. I have tried putting 0x95 in RTCAMIN ...
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1answer
88 views

32.768 kHz crystal for RTC, should the case be soldered to GND? [duplicate]

I've seen this on a few boards, but I don't know if it's the right thing to do. Should the case be soldered to GND? It is the common cylindrical package:
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3answers
810 views

Why put a voltage divider between a battery and the battery pin of an RTC?

I bought a PCB module including a DS1307 real-time clock to evaluate if that RTC is right for the system I'm designing. Here's part of the schematic: The DS1307 works with a battery voltage ...
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1answer
95 views

How to Sycnhronize STM32F4 Clock with PC Clock

I'm using 3 STM32F401RE to synchronize their clocks. My desired accuracy is of 1ms and even lesser like 0.1ms. This device is connected to PC via USB port. Question 1 : So I would like to know if I ...
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1answer
107 views

STM32F10x RTC Clock Source

I have been trying to implement calendar functionality on my STM32f103C8 using the built in RTC peripheral. Going through the RTC section of the reference manual, it states that the clock source to ...
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6answers
494 views

Calculating Milliseconds using timers in PIC and synchronizing it with DS1307 timing

I have used DS1307 in my project which gives me the values of Hour, Min, Sec but I also need values of Milliseconds. I am ...
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2answers
84 views

DS1307 timekeeping date significance (leap seconds?)

As part as a hobby project I built a relatively simple BCD binary LED clock using a PIC micro controller and a DS1307 RTC. Upon battery power loss the DS1307 resets back to 01/01/00 00:00:00 which ...
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1answer
57 views

How does buffering in the MCP79410 RTC work?

From the MCP79410 datasheet, p.16: Doesn't this mean that the data is being buffered when I read the seconds register, then again when I read the minutes register, and so on? This would mean there'...
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2answers
160 views

Why does my RTC generate interrupts faster than once per second?

I have configured an RTC module on a uC to generate interrupts every second (~32 kHz module clock with a 0x7FFF prescaler in between the counter and the clock - I hope so, seems like ~32k is the ...
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1answer
139 views

SIM900 CR2032 rtc battery backup

I would like to use a CR2032 battery to power the internal RTC of the SIM900 gsm module. The datasheet (given in the link) says that the battery should be rated at 3V. They also give the following ...
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3answers
173 views

Issue with performing I2C read operation from ds1307 to pic18F

As advised by my fellow stackers in my previous post, I tested the "Write_to_slave" function in Proteus as well in real time, by sending bytes to the RTC and the slave is responding appropriately with ...
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2answers
107 views

RTC_DS1307 + PIC18F458 displaying time and date as zeroes

I am trying to get the RTCDS1307 + PIC hardware to work in order to display the appropriate data and time. But the problem is that, its displaying the time and date as 00:00:00 and 00/00/2000 as ...
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1answer
165 views

Abracon RTCC - no startup oscillation, no SPI

I'm trying an Abracon AB1815 Real-Time Clock/Calendar (SPI interface) in a "fun" QFN16 package. It has a 17th VSS pad which is grounded. It is on a QFN17-to-DIP expander for prototyping at 1.8v. I ...
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2answers
288 views

Is there any way to calculate milliseconds from DS1307

I have a DS1307 and I have done its program and taking out time from it. In my program I have sec1,sec2 which holds the digits of seconds and same for ...
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2answers
116 views

Where to save DS1307 program to get real time value?

I am integrating DS1307 in my project and using PIC32MX795F512L MCU. I have somehow managed to do I2C communication in it and ...
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1answer
81 views

What is the purpose of SRAM in the DS1307 RTC chip and the onboard AT24C32N EEPROM chip??

I am going to interface a RTC to PIC18F and before doing so, I'd like to clear some doubts regarding the module and its connections. I am using the "Tiny RTC" as shown in this link!. The following ...
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1answer
49 views

Few queries on how to set real time clock value in DS1307

I need to integrate DS1307 RTC in my project. I have somehow managed to write I2C code and interfaced it with PIC32. I need to make a logic so that it shows real ...
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1answer
68 views

PIC16 LP drive level - do I need a damping resistor?

I'm using a 32kHz crystal oscillator with timer1 on a PIC16F1825 to provide more accurate timing for events (I want to do something every 20 minutes). The crystal circuit looks easy enough to design ...
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1answer
230 views

Can I replace watch quartz with DS3231 32 kHz output?

I'd like to know if it's possible to synchronize classical quartz clock by replacing inbuilt quartz crystal with DS3231's 32 kHz output. I need to synchronize my analog watch with RTC DS3231. Am I ...
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1answer
172 views

Error communication in I2C in PIC32 [duplicate]

Duplicate question was also asked by me and the current question has different code I have a PIC32 starter kit and I am making ...
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0answers
121 views

Transformerless Realtime Clock Issue

I have an issue with designing a Real Time Clock by using Transformerless power supply. I don't use RTC IC but I use Microchip PIC instead and 32kHz clock. I use battery of 3.3V for backup supply. The ...
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1answer
192 views

Drive relay with Npn transistor thanks to RTC and Rpi

It' s my first projet in electrical and i m not very sure about what i'm doing ... I Would like to drive a relay thanks to a Rpi and a RTC clock that has a alarm feature ( ds3231 with high-z/active ...
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4answers
2k views

How often should I query a RTC?

I've not yet used a RTC so I'm not completely sure of the "normal" way to read a real time clock. There's a few different approaches I've thought of but was hoping for some advice on it. Here are the ...
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2answers
308 views

Can I use the 32.768 kHz output from a RTC instead of an external oscillator on a PIC MCU?

Using the 28 pin PIC18(L)F2X/4XK22 and a DS3231S real time clock. The MCU has input and output pins for an external secondary oscillator and the original schematic has no RTC, but an oscillator ...
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1answer
63 views

info for RTC module needed

I have this RTC module by MikroElektronika: I need a schematic and/or user manual but it's no longer on the MikroElektronika website. (There's a similarly looking PCB but it uses a different IC ...
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2answers
441 views

Help driving 9V circuit with a 5V RTC clock interrupt pin (active low)

I am using this RTC clock module (http://datasheets.maximintegrated.com/en/ds/DS3231.pdf). The DS3231 has alarm function that can be programmed twice a day. When the alarm goes off it makes the ...
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1answer
329 views

DS1307 not counting

I've got a TinyRTC board with a DS1307 on it connected to an Arduino. Setting the time and reading is no problem (using the DS1037 Arduino lib). Weird thing though is that when I disconnect the power (...
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2answers
344 views

function of RTC

I want to know about the real time clocks or RTC. What are the function of RTC IC. Each IC has I2C interface. What it is transferring through the I2C interface. Its really hard to understand the exact ...
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2answers
66 views

DS 1307 power issue

My DS1307 stops functioning when switching the relays. It looks like a power fluctuation problem. I added 4.7uf capacitor in parallel with the power source too. Before adding 4.7uf cap DS1307 stopped ...
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2answers
585 views

DS3231 Module Circuit Teardown

I recently purchased a DS3231 RTC module to use in one of my prototypes. Now that it is complete I would like to integrate the RTC directly into my PCB instead of using a plug in module. To that ...
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2answers
69 views

STMicro library for setting RTC Alarm on Sunday is incorrect?

I'm using a stm32fxx ARM Cortex-M3. When setting an RTC alarm for Sunday, I realized that the stm32l1xx_rtc.h header file defined Sunday as: ...
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1answer
178 views

What are similarities between RTC DS1374 and RTC DS1307

I mostly work in software and not good in reading Hardware data sheets. I need help in understanding the similarities between RTC DS1374 and RTC DS1307,From below link I could make out that both ...
3
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1answer
684 views

Supercap for Backup Power (10 hours Backup Time Min.)

I am using atxmega8e5 in a design and also utilizing its Real-Time Counter to act as a Real-Time Clock. A lot of RT-Clock ICs can use a SuperCap to have backup power incase the device is unplugged or ...
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0answers
515 views

RTC DS1307 3.3V I2C and Oscilloscope impedance

I'm working on a library for STM32 to learn I2C protocol (Software I2C, not hardware). I connect my DS1307 (Sparkfun BOB-12708) : (Here is the module schematic) : I remove welding on the SJ2 jumper ...
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0answers
1k views

STM32F030 RTC wakeup from stop mode

I'm writing an app, that most of its time will spend in STOP or STANDBY mode (battery powered microsystem). I'd like the internal RTC to wakeup my STM32 every 5 minutes, enter the ISR, do its tasks in ...
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1answer
133 views

DS1302 realtime clock - pulldowns required?

I'm trying to wire up a DS1302 realtime clock, one of these: to a parallax propeller board. The datasheet says (page 4) that pulldowns are integrated into each of the main lines (looks like 3 ...
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3answers
1k views

How to turn on ATmega every 6 hours?

The board which is made with Atmega operates on battery, it should turn on every 6 hours and log some data, then go back to deep sleep to save battery consumption. Atmega32 is used and not Atiny ...
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2answers
3k views

STM32 RTC alarm not configuring for the second time

I am using STM32l151vbt6 MCU and I am trying to configure RTC Alarm for every 15th minute. (That is 0, 15, 30 and 45th minute of the every hour.) I can configure the alarm and it will work for the ...
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5answers
874 views

How is time of supplied real time clock module maintained without battery?

I am thinking about purchasing this RTC ( real time clock ) module. Since this particular item comes supplied without a battery, I wonder how the time is being kept running in the chip since it's ...
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2answers
437 views

Arduino I2C and multiple devices

I have created two projects, one with a Tiny RTC and another one with the BM180 sensor to read barometric pressure and temperature. Now I want to combine both. I'm trying to connect both - the ...
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1answer
617 views

If I'm using an RTC and ATMega328p (arduino UNO chip), do I need two crystals?

If I'm using an RTC that requires an external crystal, do I need a second external crystal for my ATMega328p? Or can the two share? What is standard practice for this kind of thing? I'm making a ...
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2answers
374 views

Periodic timer (64Hz) with ARM processor and (embedded) Linux

I want to call a function 64 times per second with a ARM processor which is running linux. (ex: Rasberry Pi or Freescale i.mx6). Ideally, I don't want too much jitter. I want to perform a task ...