PIC-based Central Heating Programmer

Central heating systems has been a good solution for many homes and even offices for quite some time now. If you own such a system I’m sure you would like to be able to control it remotely from your bed or even from a computer. This project presents such a controller. It has a 5/2 days programmer, that is 5 week days, 2 weekend days or for entire week.

The control panel allows you to turn on and off heat and hot water independently. It has 10 program entries that you can save and you have the possibility to manually override the program. Basically it is composed of two modules: the relay module that is placed at the boiler, which also has the 9 pin D connector for serial connection and the programmer panel which is connected to the relay module by a UTP cable.

The programmer panel has a 216 LCD display and five switches to select the desired program or manually control the central heating. PIC16F628A microcontroller was used in this project as the system’s brain. Dallas DS1307 was used for time management and for saving time settings in its memory. It is powered by a backup battery so it will not lose the memory data when mains power is taken. Max202 IC takes care of the serial communication.

Because of the UTP wire lenght the rellay output of the PIC can not drive the rellays directly, so a driver is used from Quasar Electronics. It is also a good idea to use protection diodes on those outputs to take care of spikes.

LCD will show the current operation mode for central heating and hot water, the on/ off state and the time. Switch 1 and 2 turns the system on/off , switches 3 and 4 are used for manual control and switch 5 is used for programmer setup. A detailed explanation of the programmer’s operation is presented in the link with all schematics and construction procedures as well as the software for the microcontroller.

PIC-based Central Heating Controller: [Link]

March 7th, 2009

Universal remote control

Universal remote control

Are you tired of carrying around one remote for the TV, one for the DVD player, one for the sound system and the list can go on. There is the possibility to buy one “good for all” remote control but it will cost you a few hundred dollars, off course there is an alternative for less money, make your own DIY universal remote control.

Any valid RC5/RC6 will be displayed on the LCD, and any code can be sent with the on board IR led’s, the LCD is the common 216 HD44780 compatible type.

The hardware is very simple, the software is written in basic and made available by the author. The Dell TV deals page sometimes has universal remotes like the Logitech Harmony One for heavily discounted prices.

I recommend this project for those interested about the RC5/RC6 codes, it can be a great alternative for radio based remote control for robotics, as you can see in one of my previous articles: IR remote robot

Universal remote control: [Link]

July 18th, 2008

Fancy LED matrix

Fancy LED matrix

The author, Olivier de Broqueville designed this circuit for hi’s son who was dreaming of a small tool able to write symbols or pictures on a screen. The solution adopted was to pilot a matrix of Leds. This way, with only some cheap transistors, common red Leds,  and a 16F628 , the dream could become reality.

Olivier also made a VB application that you can use to design patterns and export them apropriately.

Fancy LED matrix: [Link]

LCD Display with Date and Time

It’s a good idea to use LCD’s with projects like this instead of led digits, because LCD’s don’t need to be refreshed, they allow you to display many characters and it requires less I/O pins. In this project a 161 LCD Display with 4-bits interface it’s used. Time and date are displayed as HH:MM:SSx mmm dd, where: HH = Hours MM = Minutes SS = Seconds x = AM/PM mmm = Month (Jan, Feb, Mar) dd = Day.

LCD Display with Date and Time: [Link]

Simple serial ICSP PIC programmer board

ICSP, as the name suggests, allows programming of a PIC in circuit, avoiding the need to constantly take it in and out of the programmer and the subsequent bending of pins. This programmer works with any standard serial port and successfully programs a 16F628 PICs in HVP (high voltage programming) mode giving you an extra pin on PORTB – which is handy. As with the LVP programmer, it draws power for the PIC’s main supply voltage (Vdd) from a USB port.

Simple serial ICSP PIC programmer: [Via][Link]

Read about a cool usb to serial adapter here : USB to Serial Adapter

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