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Questions tagged [rtc]

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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I can't find the ppm in the clocks that STM32f103 blue pill use [closed]

I am using a blue pill with a STM32F103C8 microcontroller and for RTC reasons I am trying to find the ppm(parts per million) in the LSE, which is an external crystal clock of 32.768 kHz. I was ...
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1answer
33 views

Interfacing coin cell back up for internal RTC of ESP32

In esp wroom-32 all the VDD pins has a common connection. It includes VDD_RTC too. So in case of power failure if I switch the power between main DC source and coin cell using a mosfet, will it create ...
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6k views

Is a Real-Time Clock (RTC) necessary for real-time systems? [closed]

Assuming that we are working on a real-time Linux system and hardware which consists of high resolution timers, does having an RTC affect the real-timeliness of the system? Here it says that it ...
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2answers
212 views

RTC Power Switch for Raspberry Pi

I have done a lot of research on how to design a circuit to cut power from the pi after a safe shutdown and then turn it back on at a certain time. I am using a DS3231 RTC with an active low ALARM pin ...
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75 views

STML052K8U + DS3232: I2C not working

I have a problem, I use a microcontroller and RTC STM32L052K8U DS3232M and I can not connect via I2C with RTC, using the HAL library. From the watch constantly comes NACK. The wizard sends the correct ...
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2answers
99 views

32.768 kHz Crystal Troubleshooting

I'm at my wit's end trying to get a 32.768 kHz tuning fork crystal to work and I don't know what I'm doing wrong. First, some background: I'm using a 16MHz crystal in conjunction with an Atmega 328P-...
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1answer
308 views

Stm32 RTC wakeup from standby

I am using an STM32L053C8 and I am trying to set up an RTC wakeup event, and while I am successful, I can only do it to a max time which is a couple of seconds. I need to put it in standby and wake up ...
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1answer
28 views

DS1302 maximum current source/sink?

What is the recommended and maximum current sourcing and sinking capability on the DS1302? Is this what's given by "Active Supply Current" in the spec?
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1answer
55 views

Using RTC DS1307 in multiple programs

I'm kinda new to electronics and programming, but I managed to make a DS1307 RTC functional when it is used by only one program (I'm using C code). Buf if I try to use it in multiple programs at the ...
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1answer
35 views

where and how to connect battery for RTC of DSPIC33EP512MU814

am working on 144 pin DS PIC am not able to understand how should i connect a battery to RTC of the said pic and which pin of the pic.I need to use internal RTC of the pic
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0answers
121 views

charging Supercap for RTC usage on STM32

Relating to this Thread I have a couple Questions. I want to use the RTC and the Backup-registers of my STM32F413. Therefore I need to supply a Voltage to the VBAT Pin while the Main-supply is off (...
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2answers
390 views

Crystal Oscillator Circuit Design

I am trying to design a real-time clock circuit using a 32.768 KHz oscillator. I have no access to a datasheet for the microcontroller that I am using, but I know it requirese a 330K resistor and an ...
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390 views

RTC - High Power Consumption during standby mode and will not wakeup from wakeup timer

I am using the STM32L471RG trying to put the mcu in standby mode and then wake it up on a timer using the RTC. The mcu appears to be going to sleep, but I have been monitoring the power consumption ...
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0answers
380 views

STM32 and DS3231 connection

I need to connect real time clock DS3231 to STM32F103C8T6 microcontroller. I connected DS3231 SCL pin to STM32 PB6 pin and SDA pin to PB7. The program code compile was successful, but DS3231 made no ...
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1answer
69 views

Real time clock MCP7940N I2C interface

The RTC MCP7940N is used in the system. The microcontroller and RTC MCP7940N are connected through the I2C interface. I would to know what is the better design to read the timer value from the RTC. ...
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1answer
93 views

slaves interfere when sharing i2c bus line

I'm very new to microcontrollers, and I'm using PIC18F4620 (master) to communicate with the TCS34725 color sensor (slave), and DS1307 real time clock (slave, on board) via I2C. Right now, I'm ...
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1answer
52 views

DCF77 - No Signal detected

I'm using a Conrad DCF77 to get RTC on Beaglebone Black and wiring it so: 1--> GND | 2--> VCC 3,3 V | 3--> One of the gpios (P8_11) To read the Signal of the DCF Antenn I wrote the code: ...
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195 views

STM32F4 RTC wakeup from VBat power mode

I'm looking for a way to implement a power savings mode in an existing design. Current situation is as follows: MCU (STM32F413) and several external components share a 3.3V Vdd power rail MCU also ...
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1answer
665 views

Coin cell battery recharging circuit for RTC backup power

I am designing a system that contains an RTC to for displaying the date and time on a user interface, as well as log events with time stamps. In this particular case, the system gets powered-on at ...
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1answer
359 views

STM32 RTC - how to update?

I have a remote unit that runs a STM32L0 MCU. It is not connected to the internet but communicates with a remote PC over radio. I would like to update the RTC on the remote unit with a timestamp that ...
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1answer
93 views

Distinguish between hardware or firmware issue

I'm writing a firmware for CC3220SF from TI using a custom board I've designed. I'm facing a weird behavior and I'm not sure if it's hardware or firmware related. Here I'm looking for some hints ...
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1answer
100 views

What is a “Phantom Clock” RTC, like the Maxim DS1315 and how is it different to “regular” RTCs?

I am looking for some RTC on the Maxim website and noticed a few rather expensive chips that are labeled as "NV SRAM with Phantom Clock" and there is a dedicated "Phantom Time Chip", the DS1315. The ...
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1answer
146 views

What to do to make the clock in the microwave always correct?

My new microwave has the same problem, after setting the correct time, after a week there is already 40 minutes forward. I even thought to install my RTC in it, but the manufacturer should somehow ...
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1answer
335 views

Reading onboard-RTC registers of STM32F411

I am trying to read the values in the seconds register of on board RTC of the STM32f411E discovery board. I want to transmit the values to my serial port. I believe i have initialized the hardware ...
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1answer
34 views

Real time clock loses SCL I2C signal when backup battery is added?

I have a real time clock module in my layout (same parts as this module from Sparkfun: https://www.sparkfun.com/products/12708 ), when I have my system set up WITHOUT the backup battery, I am able to ...
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2answers
2k views

STM32 RTC freeze when power is off

I am using an STM32F745VGT6 user board with Keil µVision 5. I want to use the internal RTC calendar with the internal clock (LSI). My question is: first power on clock start 02:00:00 then time is ...
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2answers
727 views

Why Cubemx use 0x32F2 as an indicator for the RTC configuration?

I've created a program with activated RTC peripheral by cubemx. After analyzing the code and searching in the internet, I found out that the reason of writing 0x32F2 in RTC_BKP_DR1 is for checking ...
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1answer
658 views

DS3231 on Battery Power and Use of Aging Register

Currently working with DS3231M RTC module with Arduino Uno and also creating a library for this. It is working perfectly but I have a doubt that DS3231M work on both VCC(main current) and VBAT (i.e ...
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2answers
79 views

Building a clock. Need some guidance

Alright so I learned all the fundamentals of the AVR and now I am thinking of building a clock as a project. I will use the ATMega328P along with the DS1307 RTC. The time will be shown on an LCD or ...
2
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1answer
342 views

RTC battery deep discharge protection

I'm doing an application using RTC on STM32F091. I'm using a small rechargable Li-Ion battery (such as MS920SE-FL27E) as the Vbat power source for the RTC. My concern is, how can I protect the ...
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2answers
137 views

Lithium button-cell battery discharging really quickly

I am working on a board with an ARM9 (SAM9X25). On this board there is a 3.3V lithium button-cell battery powering the VDDBU power rail. It is also used with a 100kOhm pull-up resistor for WKUP with a ...
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2answers
88 views

PIC24F16KA102 SPI problem with MCP795W10 RTCC chip

I have a problem making the MCP795W10 RTCC chip working with a PIC24F16KA102 MCU. I tried RTCC chip with an Arduino and there it works perfectly. Here's is my SPI initialization code: ...
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1answer
943 views

Extend ESP8266 12 F Deep Sleep Time

I would like to extend the maximum DeepSleep time of my ESP8266 12 F Module (running the Arduino ESP8266 Firmware) to 4 hours. I just found out that the maximum Deepsleep time is 71 minutes: I found ...
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2answers
251 views

DS1307 12 hours mode

I'm trying to configure a DS1307 RTC to be in 12-hours mode. I've double and triple check my settings, and cannot understand what I have wrong. According to the documentation, bit 6 of register 0x02 ...
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1answer
138 views

7-seg. Display Multiplexing Disturbing Real-Time Clock

One of my colleagues is designing a digital clock with 7-seg displays. The clock function is shouldered by a Real-Time Clock IC, PCF8563. The RTC IC is clocked with a 32.768kHz crystal and its ...
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0answers
474 views

DS3232 over DS3231?

I am working on PIC controller and testing different RTC modules. Recently I came across DS3232 which is said to be an upgrade to DS3231. It says that DS3232 has an additional 236 bytes of SRAM. I ...
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0answers
240 views

Wait make the STM32L073RZ freeze in stopmode

With my STM32 I'm trying to configure a deepSleep mode and use RTC to generate interruption (actually each 30 seconds). When my STM start, this one configure the RTC and directly go in Stop mode. ...
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3answers
475 views

RTC chip not happy with xtal waveform

Update: This question is based on a wrong assumption, the problem has now been fixed. The problem was an incorrect register setting in the RTC. However the answers given regarding load capacitance ...
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2answers
350 views

Couldn't read the correct values of DS1302 RTC Registers

I am trying to read register values of DS1302 RTC using a PIC MCU in proteus environment. I have made two simple functions for that purpose, one is for the transfer of DATA to the RTC and other is for ...
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2answers
233 views

Reading a single byte using 3 wire interface

I am trying to communicate with DS1302 (RTC) using P16f877A MCU. I tried to read a single register (let say Hour-register) of DS1302 and put its value on a certain PORT/LCD. But I am doing something ...
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2answers
593 views

RTC (real-time clock) in STM32L4 series - date and time is not updating on the debugger variable

While using the RTC (real-time clock) in the STM32L4 series, but date and time is not updating on the variable in debugger mode. But when I stop the debugging, the variable gets updated instantly and ...
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2answers
311 views

SPI (3 wire) implementation using PIC

I am trying to connect my PIC to RTC. The RTC I am using is DS1302 with only one pin for both (Input and Output). I am trying to simulate it using PROTEUS. The problem I am facing is how can I connect ...
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426 views

STM32L152 and RTC

All I have is this problem. I want to set the my STM32L152 to go in stop mode and 4 seconds later wake up for every time. I use STM32CubeMX for configuration. This is my configuration: Enable the ...
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2answers
2k views

Use a RTC to wake up an ESP8266

I'm designing an alarm clock with an ESP8266 (Nodemcu) and a RTC module (DS3231). My system doesn't have any battery, it will be constantly powered through USB. I'd like to keep my ESP866 in deepsleep ...
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1answer
317 views

How to talk with RTC hardware by Python?

I am using DT6 custom board from Variscite . This board is connect with DART MX6 board. DT6 in below link http://www.variscite.com/products/single-board-computers/dt6customboard I need to handle the ...
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1answer
3k views

Entering stop mode on STM32L011 only works first time

I have a very typical application here - long periods of minimal current consumption (15 minutes to 24 hours sleep duration) with short periods of activity in between. In my particular case, this is ...
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1answer
661 views

How to obtain exactly the same state after deepsleep() mdbed function on a STM32L073RZ?

I try to configure my STM32 to obtain the lowest power consumption. For that I'm using deepsleep() function from mbed librairies. Before that I disable GPIO with this function ...
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1answer
179 views

8051 serial routine returns all 1s despite apparently valid data being on the bus

So, I am trying to receive synchronous serial data from a DS1306 in 3-wire mode using mode 0 of my AT89LP51ED2's USART. However, my serial read routine is returning all 1s instead of valid data, even ...
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1answer
299 views

RTC power supply

The main task is to power STM32L476 RTC directly from li-po battery (3,7V-4,2V). Unfortunately I don't have enough space for supercap or extra battery. The RTC needs only about 450 nA and has quite ...
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1answer
2k views

STM32L011 RTC wakeup function

I have a battery-constrained device with STM32L011. Right now I am using Nucleo-32 development board. In the end I want to use suspend mode with RTC to wake up every couple of minutes. First I want ...