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]
I2C (also referred as IIC or TWI) is widely used interface in embedded applications. Two wire bus initially was used by Philips and become a standard among chip vendors. I2C bus consists of two lines called Serial Data Line (SDA) and Serial Clock Line (SCL). Communication is relatively fast and short distance mainly used to communicate between sensors, RTC, EEPROM, LCD. I2C protocol allows up to 128 devices connected to those two lines where each of them has unique address. Communication between devices is master and slave based. Master generates clock signal, initiates and terminates data transfer.
Programming AVR I2C interface - [Link]
A friend of mine asked me to design a home automation for him. He wants me to build something that will communicate with his air condition through an IR receiver that it has, and it will act as a programmable timer, to turn it on and off automatically. Then i thought that i should spice it up a little bit, and make a programmable IR universal timer, or something. No matter what, i will certainly need to interface an RTC (stands for Real Time Clock) chip. This chip is responsible for keeping the time.
LCD PIC Clock with the Maxim DS1307 RTC - [Link]
I’m not sure why it is but, electronic hobbyists like to make clocks. We seem to be thrust towards them like electrons to a phosphor coated screen in a cathode ray tube. Although, at a much lower velocity. Nevertheless, I somewhat recently decided it was time to make a clock for myself. I quickly came up with several ideas of the physical implementation e.g. alarm clock, ceiling projected display etc. but, as I found out that is the easy part. I was able to distill every clock design down to the need for an (acceptably [more on acceptable accuracy later]) accurate time base, most likely 1Hz and that is what this post “Part 1″ will focus on. I will attempt to offer rational explanations as to why I decided to do things the way I did because, in case you didn’t know, there are more ways to make a time base than there are numbers on a clock’s face. Here’s how I cut my teeth skinning this kitten.
Real Time Clock - [Link]
This is a new and improved version of “Warm Tube Clock” – the open source Nixie clock project. Important hardware changes between this new version and the previous one are:
- Timekeeping is more accurate and is done by DS3231 (or DS3232) RTC IC
- There is no DS18S20 temperature sensor – the internal one of RTC IC is used instead
- Backup battery is not powering AVR anymore, but only the RTC IC
- There is no “slide switch” to control the alarm – now it is done in firmware
- Crystal on PCB is optional and can be chosen up to 16 MHz. It clocks AVR and GSCLK pin of TLC59401 IC
- Pin-compatible with previous version of Nixie “shields”
Warm Nixie Tube Clock – [Link]
Here is my home-made kit of ATmega32 microcontroller interfacing. The ATmega32 controller is rich with features like onboard 32kB in-System programmable flash, 1 KB EEPROM, 2KB SRAM, 10bit ADC (8 channel), SPI bus inteface, TWI (compatible with I2C bus) interface, an USART, analog comparator, etc. That’s why I’ve selected it to load my kit with all those features.
Make-Yourself ATmega32 Starter’s Kit with LCD, I2C, SPI, RTC, ADC interfaces – [Link]