A Real Time Clock (RTC) is a timekeeper used by microcontrollers.
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2answers
87 views
Does polling a DS1307 too frequently affect accuracy?
I did some research, and I found contradictory response on the web. I'm polling a DS1307 on an loop, with an Arduino, that takes about 20 ms to run, so basically I'm polling the I2C interface 50 times ...
0
votes
1answer
68 views
ds1307 drift too big
I have a RTC ds1307 mounted on a prototype board ( the one with 3 pin stripped ), and I'm experiencing a delay of about 5 sec/day, far too big compared to some research I did. Can that delay be caused ...
6
votes
3answers
121 views
How to calculate day of the week for RTC?
I am using MCP7940 RTC from microchip it requires to enter the day of the week as part of updating RTC with date. So how should I calculate day of the week based on the date provided by the user ?
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2answers
46 views
How to Synchronize two RTC module one internal and other external?
I am developing a data logger based on PIC controller. The PIC has internal RTC but does not have pins for connecting battery so I am using pic's internal RTC to generate interrupt every second and ...
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1answer
87 views
I2C with DS1307 hang after end of transmission
I've got a home brewed RTC with DS1307. I've put two pullup resistors on SDA and SCL lines, connected them to the Arduino 5 and 6 pin respectively. I've also provided a backup battery since I read ...
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1answer
134 views
Is there any Real time clock (RTC) which provides time resolution in microseconds?
I've been searching for high precision RTCs on Google but almost all RTCs like DS12C887, DS1307 provide time resolution in seconds which is ok for general use. But is there any RTC IC which can ...
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2answers
183 views
DS1307 RTC not working with rweather library
I'm using the DS1307 RTC together with arduino and this library
http://rweather.github.com/arduinolibs/classDS1307RTC.html
When i power the chip directly from the 5V and GND outputs from my arduino ...
1
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1answer
53 views
Using alarms with the DS1307RTC
I'm trying to wrap my head around following library:
http://rweather.github.com/arduinolibs/classDS1307RTC.html
I can see that the DS1307RTC has a writeAlarm and readAlarm function.
I'm not sure how ...
3
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3answers
97 views
DS1307-breakout-board
I want to build an RTC clock for the Raspberry Pi. Adafruit has a guide to accomplish this with Dallas DS1307. On the schematic they put a 2.2K resistor between VCC and SCL and do the same for VCC and ...
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3answers
328 views
Two wire vs. three wire serial interface for RTC
I'm looking to choose an RTC for a project I have in mind.
I have the following options (linked to datasheet):
DS1307
DS1302
The main difference seems to be the communication protocol. The DS1307 ...
0
votes
1answer
69 views
DS3232M Skips seconds when writing to SRAM
I'm using a DS3232M that works great for keeping track of the time until I try to write to the SRAM on the chip. When I use the SRAM it slows the updates of the seconds register or stops them all ...
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1answer
144 views
Multiple masters for i2c device
I have a DS1307 RTC chip that I want to interface with multiple masters.
One, an ATMega chip, will only ever really need to pull time data from the chip and the other (probably just an ATTiny) will ...
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2answers
371 views
How does GPS calculate time
How can a GPS device give exact timing even when the number of available satellites are zero?
I'm monitoring GPS data using VisualGPS.
5
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4answers
457 views
DS1307 power failure problem
the DS1307 has two power sources the main VCC source and the back up battery, which must feed the DS1307 when the power goes down and keep timing and here my problem,
I am facing a problem with the ...
1
vote
1answer
157 views
RTC on a circuit board and little green disk 00504 [closed]
I have a 110 volt powered mini fridge. after replacing a board soldered fuse with a replaceable set up I have discoverd a component that looks similar to a capacitor disk that is cracked. the fuses ...
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2answers
128 views
Ground copper pour for Crystals and Real time clocks
I am laying out a (2-layer) board, with a standard SMD Crystal as well as a Real-time clock placed on the top-side of the board.
What are guidelines regarding ground copper pour under the Crystal and ...
2
votes
2answers
272 views
Is case grounding compulsory in typical 32.768kHz crystal for Real Time Clock?
Pictures shown below is a typical 32.768kHz crystal, commonly use in Real Time Clock circuit (e.g: DS1307 & DS1337)
Referring to an earlier question posted here, it is a good practice that ...
2
votes
2answers
156 views
Device including RTC EEPROM and battery?
I am currently designing an electronic board and i got a question:
Do you know if there is any device in which are integrated an RTC, an EEPROM and a battery? I heard about this type of device (i ...
7
votes
3answers
1k views
How do you Calibrate 32.768kHz crystal for PIC24 RTCC
I'm trying to figure out the best method for PIC24 RTCC crystal calibration.
Their application note states two methods: using a lookup table and using a reference system clock.
According to them the ...
3
votes
4answers
263 views
RTC clock skipping months back
I will come to a question further down, but first a little background
We are struggling with reproducing a nasty bug that we have been getting reports for.
The symptoms clearly show that the RTC (a ...
6
votes
2answers
690 views
supercap-powered RTC?
I'm designing a ATmega-based microcontroller test board. One of the features I want to include is a Real Time Clock with a Maxim DS1307 IC. Instead of including a traditional coin cell battery backup, ...
3
votes
1answer
106 views
How to sync sensor data
Suppose I have multiple dataloggers receiving sensor data, how can I sync those signals afterwards? The most obvious way would be adding timestamps to the data, but they have independant clocks, so I ...
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2answers
805 views
PIC32 RTCC running too fast 1min = 10 sec
I'm having problems with the clock settings on my PIC32.
One minute has a duration of 10s with the current settings.
Does anyone know where I have to change my settings?
Here's the code:
// ...
2
votes
1answer
317 views
Fix a vintage computer (IBM PS/2 55SX) without a DS1287 Real Time Clock
I want to reanimate an a old vintage computer, the IBM PS/2 55SX.
The dead component is the DS1287 Real Time Clock (in particular, the battery inside).
Is it possible to simulate with a BASIC Stamp ...
0
votes
1answer
557 views
PIC32 + RTC via SPI doesn't work
I'm trying to read the time from an RTC with my PIC32 Microcontroller via SPI.
I've already succeeded in reading the time with an Arduino from the RTC.
PIC32: http://www.sparkfun.com/products/9713 ...
2
votes
2answers
499 views
DS1307 RTC Debug
I'm having trouble with getting the DS1307 RTC to work. I'm talking to it via an Arduino, and I'm just trying to get an example sketch to work. I've tried two different libraries - one from Ladyada, ...
5
votes
1answer
212 views
MCP79411 not “ticking”
I'm using the Microchip MCP79411 Real Time Clock. I can communicate with the device, read the MAC address from it, write to the EEPROM function and read back those values, but the Time and Date ...
3
votes
2answers
299 views
Are there RTCs with 100Hz output?
All RTCs I've seen so far operate from a 32.768kHz crystal, which can't be divided to 100Hz. Are there 32.000kHz RTCs?
7
votes
6answers
2k views
Why do real-time clock chips use BCD
I have seen dozens of different real-time clock chips on the market, as well as a number of processors with a built-in separately-powered real-time clock module.
Nearly all of them not only store ...
4
votes
1answer
200 views
Do I need an accurate clock for an accelerometer?
I am working on a project where I want to get very accurate data from an accelerometer. I plan on sending my data over bluetooth to be interpreted by a computer.
I am assuming that bluetooth will ...
1
vote
2answers
1k views
DS1302 Real Time Clock Question
So I am attempting to tie a real time clock (DS1302) into an Arduino and then eventually a AVR chip directly. From all of the schematics I have seen, it appears a crystal is required. I read through ...
4
votes
3answers
983 views
Smallest lithium battery backup?
I'm considering putting a small lithium battery on my Super OSD Pro boards. The battery would provide power to the RTC. I am wondering how small can you get a battery? I don't really care about ...
