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826  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: SPI buses, speed? on: June 02, 2009, 03:53:59 am
Hi halley,
the biggest problem is probably to write the client software for the SPI-slaves. I have seen many attempts to write such a client but haven't seen any working (library-)code yet.

I2C is the much simpler solution, because the Wire library already provides the neccessary infrastructure for communication using callbacks functions with the client.  

Maybe you could get by with simply running the I²C-bus at a faster speed?
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1241668644
Eberhard
827  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: starting out on: May 26, 2009, 01:42:32 am
Hi Matteo,
are you aware that the ethernet-shield does not work out of the box with an Arduino-Mega? The ethernet shield pins are arranged for the Duemilanove-board.

If you don't have any specific project in mind that requires lots of IO and/or the extra memory on a Mega, the Duemilanove+Ethernet is a good start.

I also very much appreciate that you can replace the MCU on a Duemilanove board after spilling a cup of coffee over your external hardware :o (this is how I decided I need an external programmer too and no more drink and food at the desk)

Eberhard
828  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Possible to Run Java on Arduino????? on: May 17, 2009, 03:05:18 am
Hi,
you should probably go for a more powerful platform (more expensive too) like the http://beagleboard.org/.

Eberhard
829  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: hi speed event detection on: July 01, 2008, 03:40:33 am
Hi,
try this
http://www.arduino.cc/en/Reference/AttachInterrupt
Eberhard
830  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: sources of supply on: June 28, 2008, 08:11:43 am
Quote
heck, I'll just make a start:

a) 8x8 led matrix, red, 6x6cm, rows: common anode, lens type: clear
b) 8x8 led matrix, RGB, 6x6cm, rows: common anode, lens type: clear

http://ledsee.com
http://stores.ebay.com/LEDSEE-electronics
http://stores.ebay.de/LEDSEE-electronics
http://stores.ebay.nl/LEDSEE-electronics

I'm not getting any money from them, in fact I'm going to order a few of those.

Finally, sucess  ;D

Cool, the shop-info says the Leds are ready to be shipped from China!
Not really a local supplier. :smiley

Eberhard

831  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Moving data parallelly to port D on: June 25, 2008, 03:43:56 am
Hi,
you have access to the port D on the Arduino with the command PORTD. You still have to set the io-pins as outputs, but then you can simply write fro instance
Code:
PORTD=B10101010;
to update all of the 8 pins with one command.
Eberhard

832  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: [noob-ask] burning bootloader using dt006 on: April 22, 2008, 09:46:09 am
Hi,
Quote
so, ur saying that its not possible to program using that LPT port programmer?
No, I simply don't know  smiley-sad They don't give much information(could not see a datasheet...)
Quote
What's the differrence between this LPT programmer and building my own parallel programmer?
The DIY programmer should be cheaper to build.
Quote
I realize that the LPT programmer from my friend is 2x5 pins.
This page http://www.evilmadscientist.com/article.php/avrtargetboards has some info on the different pinouts (2x3 vs. 2x5  pins) The original arduino-board uses the 6Pin-version.
Eberhard
833  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: [noob-ask] burning bootloader using dt006 on: April 22, 2008, 06:09:18 am
Hi, i would either build it myself http://www.arduino.cc/en/Hacking/ParallelProgrammer

or buy an AT AVR-ISP MK2 since there is a good chance your next computer will not have an LPT-port any more.

Bad news is the AV-ISP MK2
http://www.reichelt.de/?;ACTION=3;LA=2;GROUP=A38;GROUPID=2969;ARTICLE=45040;START=0;SORT=artnr;OFFSET=16;SID=26UujgjqwQARoAADzbZf0118999ad3232aadee17e69f6f87e288e
seems to be out of stock in germany (www.segor.de + www.reichelt.de) right now  :-?

Eberhard
834  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: buying advice shift registers on: June 04, 2008, 03:27:26 am
Quote
I used the following formula to calculate the ohms:

Basically though, if you want 20mA, the resistor should be ([supply voltage] - [led voltage]) / 0.02.  Or 50*(supply voltage - led voltage).

So I calculated: 5V - 3.5 (led voltage) / 0.02 = 75 ohms

=> P = V^2/R with this formula I get around 0.33 watts?
Is this not correct?
The formula is correct. Though, since you know both the voltage and the current through the resistor its easier to use
P=U*I=1.5V*0,02A=0,03W

But as you can see you got the actual calculation wrong. It's 0,03W not 0,3W.

Quote
About the 0.25w items on that site: what I don't understand is why there are several items available
starting from 1 W upwards. Is not this one the actual resistance value?

best
yves
Since all the values given in the table are typical resistor values they got an error in their database. The values should read 1Ohm, 27kOhm, 560kOhm etc.

But I'm not sure about the prices, looks like you have to order a minimum of 1000 Resistors per value? (that would almost match the prices in Germany 5€ if you order >=1000)

Eberhard
835  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: buying advice shift registers on: June 04, 2008, 01:54:25 am
Hi,
if you have problems finding a local shop here are 2 german distributors :

Segor : http://www.segor.de/ Actually the distributor for the Arduino over here, and all sorts of electronic components.

Reichelt : http://www.reichelt.de/ In germany its probably the cheapest online shop for electronic components. (But check with Segor on individual items.)

Eberhard
836  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: buying advice shift registers on: June 03, 2008, 02:36:54 am
Quote
hi there

I'll buy some shift registers in the near future and would like to ask which one
I should buy... I'll certainly go for the 74HC595 but which version. There is one
with DIL-16 and one with SO-16 enclosure. I unfortunatly don't know what that
means... can anyone help me?
You want DIL-16, because the SO-16 are very,very small therefore hard to solder especially if you are a beginner in electronics.
Quote
(oh by the way, is it normal that white LEDs are alot more expensive than all
the other colors?)
Yes.

Eberhard
837  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Multiple Arduinos on: June 02, 2008, 08:43:43 am
Hi,
this depends on the Operating System the you application is running on. I think there is a solution for all of them. What os will be used?
Eberhard
838  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: wii nunchuck hacking on: May 30, 2008, 03:52:51 am
Hi,
Quote
After installing successively the versions 011 and 010 the compilation is accompanied by a lot of errors.
Care to share the error-messages with us?
Seriously, how should we be able to help you, if we don't know what is going on at all?

Eberhard
839  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: 13 segment character on: May 26, 2008, 08:53:43 am
Hi, if you don't need the analog pins you can use them as 6 additional digital IO-Pins

This is taken from the from the reference http://www.arduino.cc/en/Reference/DigitalWrite
Quote
Note

The analog input pins can also be used as digital pins, referred to as numbers 14 (analog input 0) to 19 (analog input 5).
Eberhard
840  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: How to convert 5v TTL to 3.3v and vice versa? on: May 20, 2008, 06:42:26 am
Hi,
for shifting high to low levels I recently discovered the 74HC4050. It provides 6 independent level-shifter channels to shift from 5V -> 3.3V .

Its available in DIP-package which is a killer-feature for me :-)

Eberhard  
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