The most popular RTC for the Arduino is the DS1307. However, it does have some drawbacks, the most notable of which is that its operating voltage is 5v, which means it cannot be used with 3.3v projects. The Maxim DS1339 however, features a wide tolerance of voltages from 2.97V-5.5V with the typical voltage as 3.3v, a battery backup, two alarms, and a trickle charger. The breakout board here packages the DS1339 with the components and connections necessary to use with your Arduino projects easily.
MAX DS1339 RTC real time clock for arduino - [Link]
If your design contains Microchip’s MCP79XXX series RTC chips and you are running into troubles using them, this technical brief is intended to resolve several of the commonly-asked questions regarding developing stand-alone serial interface real-time clock/ calendar devices with MCP79XXX. Similarly, there’s also another application note from Microchip which provides detail assistance and guidance in using these RTC devices.
Q&A concerning Microchip’s MCP79XXX RTC chips - [Link]
The MAX31629 I2C digital thermometer and real-time clock (RTC) integrates the critical functions of a real-time clock and a temperature monitor in a small-outline 8-pin TDFN package. Communication to the device is accomplished through an I2C interface. The wide power-supply range and minimal power requirement of the device allow for accurate time/temperature measurements in battery-powered applications. The digital thermometer provides 9-bit to 12-bit temperature readings that indicate the temperature of the device.
MAX31629 – I2C Digital Thermometer and Real-Time Clock - [Link]
luca @ lucadentella.it build a nice app that let you configure an RTC chip using a PC GUI and your Arduino board. The system is composed by two elements, the PC GUI written in C# and a sketch running on Arduino. The RTC is connected on the Arduino using I2C interface and Arduino is connected to PC using a simple serial protocol.
I chose to use the Adafruit’s RTClib library to talk with the DS1307 chip, that is for sure one of the most used RTC in the hobbistic world. The connection between the IC and Arduino is established using the I2C bus.
RTCSetup – configure an RTC chip using your PC - [Link]
This is a collection of Maxim’s newest real-time clock ICs.
This real-time clock IC operates with very low current and is compatible with high-ESR crystals for a space saving, low-cost design. Read the rest of this entry »
Here is a programmable timer project by Victor. It’s PIC18F4550 based and uses a DS1307 real time clock chip to keep time. A small 12 volt relay acts as the switch. [via]
This project, like others before, has started out of need: our 30+ year old mechanical timer for the central heater of the house has finally given it up. It would have been faster and cheaper to get a replacement from the local hardware store, but I decided to learn something new and I set out to create a digital version of it.
Programmable timer switch - [Link]
Alexander Holler writes: [via]
This page describes how you can use a small AVR device and a real-time clock (RTC) to build a hot-pluggable USB real-time clock (I’ve named it just usb-rtc), mainly for usage with ultra-low-cost hardware meant to be used with Linux.
The overall cost for one of those thingies I’m describing here is about 15€-20€, which isn’t really cheap. But I find it a valuable thingy because the result is a hot pluggable RTC, usable by almost any device which has USB. So it’s very likely you will use it for much longer than the device you currently want to build or search it for. In addition you might want to use it as a (hot pluggable) USB-I2C adapter too. The software I’m describing below already supports that.
How to build an USB real-time clock - [Link]
The DS1339A serial real-time clock (RTC) is a low-power clock/date device with two programmable time-of-day alarms and a programmable square-wave output. Address and data are transferred serially through an I²C bus. The clock/date provides seconds, minutes, hours, day, date, month, and year information. The date at the end of the month is automatically adjusted for months with fewer than 31 days, including corrections for leap year. The clock operates in either the 24-hour or 12-hour format with AM/PM indicator. The DS1339A has a builtin power-sense circuit that detects power failures and automatically switches to the backup supply, maintaining time, date, and alarm operation.
Low-Current, I²C, Serial Real-Time Clock - [Link]
The DS3231M breakout board is a compact breakout board for the new DS3231M high precision real time clock chip. With it, you can add timekeeping and alarm functionality to any Arduino (or other microcontroller that supports the I2C/TWI protocol).
The board comes with an onboard CR1220 backup battery (keeps time when main power is disconnected). All pins on the chip are broken out, allowing you to use extra features such as 1Hz and 32kHz square wave output, interrupt on alarm and reset.
DS3231M Real Time Clock Breakout - [Link]
In this third blog post, I’m going to show you the logical view of my Nixie clock and two of its main elements: the real time clock, to keep track of the current time, and the expander, to add more I/O lines.
RTC and port expander for an Arduino nixie clock - [Link]