hi,

wiring really isn't a big deal. just connect all max7219 to vcc, ground and the common clock signal from your arduino.

the first chip's data-in is connected to your arduino. each following chip's data-in has to be connected to the data-out of the previuos max7219.

if you need help on the code side:
basically each chip expects (and can only hold)16 bits of data as a command (8bits register + 8 bits data). if you send more than 16 bits, the bits which you sent first will be shifted out to the data-out. meaning a chip will pass the message to the next max7219.

lets say command A (for the FIRST max chip) would be

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

and message B (for the second max7219 in your chain)

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1


just send message B first, then message A and then latch the data. (like "kg4wsv" already wrote above)

-> 0000000000000000,1111111111111111

after the 16th bit is sent (that's the last '1' in my example) the first chip will start to output on it's data-out pin, meaning it will pass the first command to the next chip (at the same time "forgetting" this bit).

it's the same for 3 or more

hi trialex,

though i'm reading in safe mode only today, i followed your links. man, hope the pages are still up tomorrow :-)
it definetely helped me waking up this morning. so thanks, for sharing.

best, kuk

you'll have to take the time between two presses to calculate the differnce in Milliseconds.
so the first thing is to distinguish between the 1st and the 2nd press.
use a variable to count them.

int           numberOfButtonPresses = 0;
long int    time_1;
long int    time_2;

long int    time_difference;                      //thats what your looking for



now in your main loop wait for the action.

if (buttonPressed && numberOfButtonPresses== 0 ) {  //first action
 //maybe reset millis ... resetMilis();
 //store the "start time"
 time_1 = millis();
 numberOfButtonPresses++;
}

if (buttonPressed && numberOfButtonPresses== 1 ) {  //SECOND action
 //store the "end time"
 time_2 = millis();
 time_difference=time_2 - time_1;
 numberOfButtonPresses=0;  //reset button counter for the next time
}

http://www.theledlight.com/LED101.html

Source Voltage = 5 V (USB thingy)
LED Drops:
 red =1,2–1,8 V
 yellow =2,1V
 green = 3,0–3,4 V

If i think about these values, I dont even know what it tells me.

current ^= water flow, think liters/second
voltage ^= water pressure in your  pipeline
resistor ^= diameter of your valve (more OHM -> smaller diameter)

U = R*I (volt= ohm/ampere) (higher pressure -> more water / narrower valve -> less water )

need a specific amount of water per minute? use a "calculated" valve.

-> U/I = R

i can't think of an analogy to the voltage drop (anyone?), but effectively it reduces the voltage that you use for the calculations.
if the voltage drop is 1V use 4V instead of 5V to find the right valve.

it sounds as if you're going to drive your LEDs in parrallel in order to light them up individually. so you can calculate your values independently from each other.

best, kuk

It seems that they do not like runing i\under usb power and only cooperate on battery :S

are your servos powered from the +9v pin or +5v pin on your arduino? the 9v pin only carries power when you're using an external power-source (not USB).

Awesome.  I added a link to it on the playground: http://www.arduino.cc/playground/Main/Resources.  I hope people will continue to build on it.

would it be technically possible to allow the javascript embed of partlists in this YaBB installation?
how about flash from trusted servers (youtube) or is it disabled for the same [security?] reasons?

 

One great way to collect this information (besides answers here or a page on the playground) might be a parts list on Octopart, which would allow people to buy the parts from a variety of distributors.  

i starte to explore the octopart.com option.

here's a quick public partslist:
http://octopart.com/partlist/view?id=NjEzNzMy

it seems you can't search for partlists on octopart. could someone of you try if it's possible to add items to that list and save it under a new name?

plus: i didn't add resistors just because i couldn't find any 1/4W through holes in that billion of SMT parts. how do you search for them?

as for manufacturers/models: i chose those parts first in the search result that had a pdf datasheet attached.
maybe we should discuss individual parts and do seperate lists for special ICs/caps/Leds etc. That way i would be easier to explain them in the partlist description (individual parts can't be commented i think).

//kuk

PS: it seems the octopart list can also be embedded in webpages using one line javascript. unfortunately YaBB doesn't like this :-(


EDIT: individual parts _can_ be commented. it also seems that anyone can create a personal copy of list and edit/publish it under his/her own name!
so if you know of components that are essential, somehow "general purpose" please put it in this thread with a short description and i put them on the list.


i

this topic comes up from time to time. the extra realtime component is a save bet if you use it correctly. still an arduino should be enough to build an accurate clock. if you notice an offset (because of crystal tolerances) you should also be able to compensate for it in your code. as kg4wsv wrote, the actual frequency is dependant on the crystal but shouldn't change over time. me too says go ahead! and keep us informed. it's a shame that there's no arduino-only clock code out there yet.

ku

shouldn't it be daniel0002?

welcome back!  

hi jds,
i'm wondering as well, but didn't dare to tell that i'm missing a person on an internet forum :-)
i can imagine different reasons (for myself) to unsubscribe from a forum, so i think we'll just have to live with it. i just hope there were no hard feelings involved.

kuk

i found this pdf: http://manuals.info.apple.com/en/logic/Logic_Control_Surfaces_Info.pdf

it seems indeed logic is able to send meter levels as sysEx (non standard) midi messages. since sysEx messages don't have a fixed length (like 3 bytes for a "Note On") it might get a little tricky to get into this. i'd recommend trying the midi monitor that i mentioned. maybe all your info is in the pdf, i didn't really read it.

i mean thru MIDI. I assume Logic pro or Cubase are able to send, as MIDI data, the Level meters they have on their mixers.

i'm not sure if they do, but if i would be interested to know. interpreting midi is no big deal, if you know the status byte of the "audio volume message". if you don't know, you can use an application like midi monitor (os x) to see what kind of messages are sent at all.

is it possible to build something similar but "digital" for midi controller?
(thus, it can read the Level meters from Logic, cubase, etc..)

it depends on how you can make those apps send you your information. if it's midi no problem, but if we're talking about analog audio (from a headphones jack for example) you can try hooking it directly to some analog pin on your board plus ground to ground. note that the signal will between -1V and + 1V (i think) so you may need to amplify it to use the full range of the analog port (0-5V).

you could start by getting sound/volume into your arduino. there's a how-to for microphone input here : http://tinkerlog.com/2007/05/20/cheap-sound-sensor-for-avr/

i think all arduinos traditionally come with a ~220? build-in resistor on pin 13. if you connect a LED to it you can take it as a debugging help in your program.
this will also show if your atmega is still alive because the bootloader blinks pin 13 on reset.