Instructables
Picture of DIY TiX Clock
Here's my instructable for a DIY TiX clock.  It is powered by an AVR microcontroller.  The display is made up using a piece of reflector grid you find covering office lights, some smoked perspex, a diffuser and a bunch of LED's.  The Idea came from the Tix clocks you can buy at various places on the web, but nothing beats making it yourself.  It is a talking point in the lounge and once you are used to reading it, you can tell the time in a jiffy.


 
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Step 1: The Electronics

The first prototype was made using Vero strip board.  The layout on strip board is fairly straight forward.  The Transistors in the top left are row drivers and the IC's on the right are  transistor arrays that are the column drivers (see circuit diagram at the end of instructable for more info).  This allows me to get a bit more current to the LEDs to make them brighter.  The Transistor array IC's can be replaced with transistors if you like.  You will find circuit diagrams and software at the end of this instructable with which I have included an Eagle PCB layout design as well for a single sided board that combines the controller and display board into one.

Note that if you etch your own PCB the LED's are mounted as normal thru hole components but the IC's, links and other components are placed on the copper side of the board.  The LED's and links will need to be mounted first as the AVR covers some of the LED solder points.  Details in the pictures.

Step 2: The Display

The display is made up of a sandwich of the display Board, The square reflector, a diffuser and a smoked perspex window.  You can place a sheet of tinfoil under the LED's to give more reflection, just make sure you cut a hole in tinfoil around a legs of each LED so it doesn't short things out.  I also sanded the lens of each led to distribute the light more.

The first three photos show the strip board version, the remainder the etched PCB version.
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robkirk1 month ago

Compact version. When making the led grid, miss the square separating the digits if you want it smaller.

robkirk4 months ago
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gweeds (author)  robkirk4 months ago
Hmmm, maybe I got the JTAG fuse bit around the other way. Change the JTAG fuse bit, reprogram and see what you get.
robkirk gweeds3 months ago

one last thing is id love for it to be 3 second instead of 5 :/ :)

gweeds (author)  robkirk3 months ago

Hi Rob? 3 seconds instead of five for the change time? is that what you mean?

robkirk gweeds1 month ago

hiya gweeds if you ever get the time please could you do the 3 second change time tweak and upload the hex? many thanks. Also if you had a variable resistor pot on the positive feeding the 3 bc transistors would this be able to dim the leds? and could you even incorporate a photocell to this and have it done automatically.

robkirk gweeds3 months ago

Yes gweeds i thought that 3 seconds would be about the optimum time for changing the leds in time. one and five seconds is still a good option so if you could just add three seconds as an option it would be awesome. When you have time of course no rush :) (if you even want to do it that is haha). Btw i deleted a lot of posts that won't help future people as i kind of spammed here whilst being a noob :).

robkirk gweeds4 months ago
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robkirk robkirk4 months ago
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gweeds (author)  robkirk4 months ago

Oh don't give up hope, it does work I have one here that works fine. I also have someone else who built one and has it working.

repei gweeds3 months ago

About the need to disable jtag I understand, but what is necessary to change the pin 4 to pin 25 have Mr. gweeds, thank him for that, it works out ok

gweeds (author)  robkirk4 months ago

nope, those bits look like that on mine too.

robkirk gweeds4 months ago

just to confirm jtag refers to the jtagen setting

gweeds (author)  robkirk4 months ago

Hi again Rob, ok, so I downloaded the same hex file of my web site, and programmed it to my Tix clock using your program and programmer and using the fuse bits I suggested and it works as it should. Before I programmed it, I read the fuse bits and mine were set to 84 and 51. However the difference doesn't refer to anything that might affect operation. I will double check the diagram I have listed here with the board I have in my hand here a little later. Be good to get everything correct eh! :)

robkirk gweeds4 months ago
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gweeds (author)  robkirk4 months ago

There you go, updated schematic uploaded.

robkirk gweeds4 months ago
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gweeds (author)  robkirk4 months ago

Right, so I have had a good look, yes the diagram on here is an old version compared to the code, I shall fix that. The differences are:

Pin 2 of IC3 should go to Pin 25 of the AVR (this drives the last column)

S1 (set) goes to pin 2 of the AVR

S2 (Up) goes to Pin 3 of the AVR

That should get you going...

robkirk2 months ago

i was just looking at different leds and found a type called straw hat leds that spread the light evenly like a lightbulb instead of in a beam, wish i had known of these before i might even redo them with this type in the future when i get bored as my less are very close to the acrylic and you can see the brightness in the middle even with them lightly sanded :)

http://electronics.stackexchange.com/questions/2089/what-is-the-advantage-of-a-straw-hat-led

gweeds (author)  robkirk2 months ago

yes they use them for LED christmas and party lighting. you might end up with a darker circle in the middle, as in the opposite of what you have now.

robkirk gweeds2 months ago

tweeds just a thought but how hard would it be to incorporate a dimming feature either automatic or manual?

robkirk gweeds2 months ago

I've gone for just diffused standard leds this time, see how they work out i shouldn't have to sand them and they are not high intensity so shouldn't be to bright i hope they are bright enough though. oh and i fixed the 3 dim orange less it was either a solder issue or faulty leds as i replaced them and seems fine now.

robkirk2 months ago

Added a few finishing touches today which included blu tak (a form of putty/plasticine) around all the inside grid rows to stop light leakage. Very pleasing to see the squares so crisp now. Also painted the grid black so you can't see it under the smoked acrylic. Added some push buttons on the back by drilling the back piece of acrylic and securing them with lock nuts then soldered onto the main board (my vero board is a mess with jumper wires everywhere and no doubt cold solder joints everywhere and it was 3rd time lucky as I'm no good at soldering). Officially finished and very pleased with it.

robkirk robkirk2 months ago

oh and i used white baking paper to diffuse in place of the thick tracing paper gweeds suggested and it works very well.

gweeds (author)  robkirk2 months ago

baking paper, now why didn't I think of that. That's what I like about instructables, you see so many different uses for different products! :)

robkirk gweeds2 months ago
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gweeds (author)  robkirk2 months ago

Hmm yes I did see that, and no sorry mine doesn't do that, I wouldn't have put up with it. I would check your wiring and soldering, it could be the smallest of solder bridges that can cause that sort of effect.

robkirk made it!3 months ago

Finally had time to put the enclosure together it looks sweet with the smoked acrylic and instead of egg crate reflective squares which i found hard to source i used 2cm square plastic grid which is actually a Chinese plate dryer rack. didn't go to the trouble of etching a pcb but managed to fit a vero board inside the enclosure which btw is not as good quality as gweeds enclosure. Thanks to gweeds for helping me and anyone who thinks they can't do this because of limited knowledge of micro controllers i say go for it as i was a complete noob at electronics and managed it from scratch just be prepared to wait for different parts and to learn as you go.

securedownload.jpegsecuredownload-3.jpeg
robkirk robkirk3 months ago

gweeds (author)  robkirk3 months ago

Looking good Rob!

robkirk made it!4 months ago

finally i have a working prototype, now i have this i shouldn't have to bother you anymore tweeds lol :) many thanks for helping me troubleshoot and even redesigning the schematic because of me. one final question is when i plug my 5 volt breadboard supply into the wall charger it goes mad and all the less flicker. is this to do with the hz being messed up by the 50hz wall transformer? when its plugged into my usb 5v laptop it works fine.

Photo on 25-03-2014 at 17.20.jpg
gweeds (author)  robkirk4 months ago

All good, glad it is going!, I hope the new schematic is a bit easier to follow as well.

robkirk robkirk4 months ago

nope its working fine actually from a different 5v wall charger :)

robkirk4 months ago

many many thanks i might be speaking to soon but i think i solved it, on that extreme burner program i was not clicking write tick box when programming so the jtag must not have been programmed off!!!! i feel such an idiot! ill post back when i rewire the breadboard again as im only testing that pin atm thanks again gweeds your awesome!

gweeds (author)  robkirk4 months ago
Ah yes, I did that trick too!
repei4 months ago

работает все,кроме порта PB3 pin4. AVR

gweeds (author)  repei4 months ago

Hi there, I have uploaded a updated schematic, that with the current code and JTAG disabled should work.

gweeds (author)  repei4 months ago

Hi there, make sure you have disabled the JTAG interface.

Привет там, убедитесь, что у вас есть интерфейс JTAG отключена

repei gweeds4 months ago

Благодарю за быстрый отклик!Да jtag отключен,иначе не выключался нижний ряд led -3,6,9,12 ....27.Программирую PoniProg через ICSP.У PoniProg переключение FUSE обратное для AVR.На PIN 4 нет логической 0 или 1 ,состояние неопределено,но ЕСЛИ в исходном коде ПОМЕНЯТЬ строку DDRB = & B00000000 на DDRB = & B00001111, то на PIN-4 появляется логическая 1, и столбец led 25,26,27 светит постоянно.Собрано на отладочной плате.-https://www.olimex.com/Products/AVR/Proto/AVR-P40-... Foto в привязанность.Один резистор для драйвера pin4 не видно ,он внизу платы.



jtag off pony.JPGled jtag off.JPGled jtag on.JPGcode.JPG
gweeds (author)  repei4 months ago

Hi again, sorry google has a bit of problems translating that reply. I think I may have mucked up the code and schematic a bit when I uploaded this instructable. Connect the last column to pin 25 instead of pin 4.

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