Selfmade stackmat display (II)

[fw]

Hi,

some of you have asked me about this. So, you have waited long enough.

Here is my first version:

http://hackvalue.de/elektronik/stackmat/

Tell me what you think

 

[nitrocan]

hings you will need:

* Atmel Atmega88 Microcontroller (datasheet)
* Maxim MAX7219 Display controller (datasheet)
* Maxim MAX232 Level shifter (datasheet)
* 7805 voltage regulator (datasheet)
* six 100 nF ceramic capacitors
* one 47 µF electrolytic capacitor
* five 1 µF electrolytic capactors
* three 10 kΩ resistors
* five LEDs (power, case light, three stackmat status LEDs)
* resistors for the five LEDs (value depends on the LEDs! Look at the datasheet!)
* optionally an ISP socket for easier software updates
* some kind of Atmel ISP programmer for getting the software onto the Atmel Microcontroller (don't buy a programmer from Atmel! They are very expensive. There are many cheap or easy to build ISP programmers)
* five 7-segment LED displays with common cathode (not common anode!)
* two diodes
* one two-state stereo switch for power selection, one two-state mono switch
* three buttons

I don't think those are such easy supplies to get

 

[fw]

yes, they are. every electronic shop has this. I ordered all parts by one shop. No problem at all. Its all "standard stuff".

 

[jfly]

Wow! Very nice project. I wish I knew anything about electronics. Great documentation of the stackmat signal, I had no idea there was a name for the signal (RS232 serial).
I've always wanted a very portable electronic device that I could plug my stackmat into and get averages and statistics. The most readily available device I can think of would be a cell phone with a microphone port. Most cell phones run java too, how cool would a CCT port to mobile devices be?

 

[shelley]

how cool would a CCT port to mobile devices be?

It would be awesome cool.

 

[Pedro]

WOW!
That is some piece of art!

great work, man

now you gotta tell me where you found those big led displays...I could find only small ones (the ones in your first video)

 

[hisoka]

just some suggestions:

why not put a counter to display the number of times your display has saved?
and one more thing, your display has button for saving times, but does it have a button for clearing the saved times in the memory?

anyway, your display is really great! not only do you have great electronic skills but awesome packaging skills as well!

 

[fw]

No, there is no button for deleting single times. You can delete all times by just turning the thing off and on again. I will think about your "display the number of times that has been saved" feature. I am also not sure about the averrage yet. At the moment, it just calculates the average. Best and worst time are not deleted... But that is just a minor software update..

Pedro: The LED displays are called "Jumbo LED-Anzeige LDS1151URC" and I got them from a german online electronics shop very cheap (http://www.pollin.de/shop/shop.php?cf=detail.php&pg=OA==&a=ODU0OTc4OTk=&w=OTg4OTk4&ts=0)

 

[jfly]

What happens if you press the "Save Time" button while the timer is running? Could you automatically add the time when you stop the stackmat?

 

[fw]

What happens if you press the "Save Time" button while the timer is running?

Nothing. The time can only be saved when the timer has been stopped and it can only be saved once (you cant press the buton twice without resetting the timer in between). Yes, auto saving could be done by a small software modicifation. I also thought about a switch at the top of the save to toggle between the function of button 2 ("save time and autodelete" vs. "delete time and autosave")...

Right now, I am also thinking about a switch for toggling between "display mode" (what its doing right now) and "timer mode" (for beeing able to use it as a stand alone timer). That would require only software modifications, that hardware can already do this, and there is plenty of room for a bigger software in the microcontrollers flash at the moment..

 

[Karthik]

What protocol does the stack mat use to transfer data to the displays?RS-232?What is the baud rate?



Edit: Sorry, I read through the documentation and found it.
BTW, how did you figure out the baud rate? Can you give a little more details?

 

[fw]

BTW, how did you figure out the baud rate? Can you give a little more details?

I played around with the signal and displayed it on an oscilloscope (there is snapshot of the oscilloscope on the website). I was quite sure that it is RS232 after some time.. 8 databits, no parity, one stopbit ("8N1") is pretty standard, so I tried that first.. and then I tried all default baud rates..

floater81, the author of a java program which interprets the stackmat signal, told me how to decode the 9 byte packets..

 

[Pedro]

why did you use "common cathode" displays?
is it possible to change something and use anode ones?

 

[EmersonHerrmann]

That is a really great set-up, I like how it shows if you have the left or the right hand on the pad. Very nifty!

 

[fw]

why did you use "common cathode" displays?
is it possible to change something and use anode ones?

Because the display controller (MAX7219) only works with common cathode. I am sure there are other display controllers who can also work with common anode displays, but the MAX7219 doesnt..

 

[fw]

That is a really great set-up, I like how it shows if you have the left or the right hand on the pad. Very nifty!

Yeah, I love that too I was suprised to see that the protocol even transmits this information, because neither the stackmat timer nor the original stackmat display has this feature

 

[hisoka]

did anyone tried to recreate this?

 

[MHordecki]

Simply amazing! Great work!

Did you know you're the first person ever that has published a stackmat->display signal protocol? Thank you very much!

 

[Mozza314]

I've always wanted a very portable electronic device that I could plug my stackmat into and get averages and statistics. The most readily available device I can think of would be a cell phone with a microphone port. Most cell phones run java too, how cool would a CCT port to mobile devices be?

I think this is an amazing idea. I hope I remember this when I decide to learn java one day! As for the need for a microphone port... all phones basically have a handsfree capability, so I don't see why a handsfree thing couldn't be taken apart and wired up to connect to the stackmat. Hell, if you have an FM transmitter, many phones have a radio tuner in them

 

[fcwy1]

Is it possible for you to make and sell it?