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46  Forum 2005-2010 (read only) / Interfacing / Re: Proto Shield v.1a questions on: October 23, 2006, 02:57:44 am
I just checked, the LEDs share ground with the ICSP. It seems they aren't connected to any Arduino pins, they need to be hooked up to my own circuitry or can be connected to any pin I like.
47  Forum 2005-2010 (read only) / Interfacing / Proto Shield v.1a questions on: October 23, 2006, 02:50:31 am
I have some questions regarding the proto Shield v.1a.



What resistors do I have to add for R1 and R2?
Which pins are LED1&2 connected to, or do I have to connect them to my own circuit? LED1 seems to be connected to the ICSP.
What is the function of S1, is it connected to the reset pin?

If the digital pin blocks had the right spacing a normal piece of perfboard coul be used. Too bad it won't fit without bending some pins. I still like it.
48  Forum 2005-2010 (read only) / Interfacing / Re: 220V elements? on: November 29, 2006, 05:09:32 am
http://todbot.com/blog/wp-content/uploads/2006/10/arduino_spooky_projects_class4.pdf

How to connect a relay is also shown on page 40 of this (excellent!) document.
49  Forum 2005-2010 (read only) / Interfacing / Re: alarm clock on: November 20, 2006, 07:15:03 pm
There are state operated time transmitters which are very accurate and reliable. Many countries have them. You can usually get the required hardware for pretty cheap.

http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1162986904


http://www.npl.co.uk/time/
http://en.wikipedia.org/wiki/DCF77
http://tf.nist.gov/index.html
http://en.wikipedia.org/wiki/Radio_clock

50  Forum 2005-2010 (read only) / Interfacing / Re: Read a piezo sensor & value of resistor on: November 20, 2006, 04:31:58 am
> Because I'm a beginner, I don't know why I have to use 1M resistor to my piezo.

There was a discussion about this recently. Search for username todbot.

> I only have 10kohm and 220ohm resistors. (If I must use 1Mohm resistor, I have buy it.)
 
Buy some. They won't break the bank.

> 1. What is the difference if I use 10k resistor on behalf of 1M resistor?

It won't work.

> 2. Can I use 10k resistor on behalf of 1M resistor?

As far as I know, no you can't.

> 3. If I connect piezos to MC14067B, should I connect 1M resistors to each analog input of MC14067B?

Not sure. Probably yes.
51  Forum 2005-2010 (read only) / Interfacing / Re: Need help with Analog in on: November 14, 2006, 01:04:03 pm
I seem to remember that one of the moderators recently said that exponentiation (^) doesn't work. I don't think that declaring all these variables as integers and then performing such complicated calculations with them works either. I doubt the Arduino can handle 'log', maybe somebody else with more knowledge can comment on that?

52  Forum 2005-2010 (read only) / Interfacing / Re: Need help with Analog in on: November 14, 2006, 05:28:25 am
Did you declare val as an integer? Because you divide it by 4.6, and I don't know if that will work.
53  Forum 2005-2010 (read only) / Interfacing / Re: Need help with Analog in on: November 13, 2006, 01:04:23 pm
Third post in a row.  :smiley

> Sensor span is 4.8 - 0.2 = 4.6V.
> ( 4.067 / 4.6 ) * 1150 = 1016mbar

Actually this should be ( 4.067 / 4.6 ) * (1150-150)... or something like that
54  Forum 2005-2010 (read only) / Interfacing / Re: Need help with Analog in on: November 13, 2006, 12:56:38 pm
From the datasheet:

Vout = VS x (0.009 x P – 0.095) ± (Pressure Error x Temp. Factor x 0.009 x VS)
VS = 5.1 ± 0.25 Vdc

Let's assume VS = 5V, P = 1016mbar = 101.6kPa and simplify this a bit to:

Vout = VS x (0.009 x P – 0.095)
Vout = 4.097V

which is pretty close to what I calculated above, 4.067V. Certainly within the error margin, even though we rounded a few numbers (like sensor span).
55  Forum 2005-2010 (read only) / Interfacing / Re: Need help with Analog in on: November 13, 2006, 12:07:13 pm
According to the datasheet the sensor will produce a signal of about 4.8V at 1150mbar and approx. 0.2V at 150mbar.

5V / 1024 = 5mV
833 * ( 5V / 1024 ) = 4.067V <---- this is the voltage your sensor produces.

Sensor span is 4.8 - 0.2 = 4.6V.

( 4.067 / 4.6 ) * 1150 = 1016mbar  <----- this is your current ambient air pressure
56  Forum 2005-2010 (read only) / Interfacing / Re: Accidental proximity sensor. on: October 30, 2006, 07:35:20 am
I'm just guessing, but to me the following seems to happen here:
You declared pin 7 as a digital input, and now it's floating. That means it's neither connected to HIGH nor to LOW (+5V or ground) and the Arduino doesn't quite know which state the pin is. That's why digital switches usually need to be connected to either HIGH or LOW with a pull-up or pull down resistor, do produce a defined state which the Arduino can detect.
57  Forum 2005-2010 (read only) / Interfacing / Re: servo/ motor problems on: November 13, 2006, 06:41:01 am
Serial Controlled Variable Speed Motor
Control the speed of a small DC motor with nothing but the serial port on your computer, a single MOSFET, and some trivial software.

http://www.instructables.com/id/E1PR6UUL0REUF10PO4/?ALLSTEPS

I'm sure this principle can be used with the Arduino, too.
58  Forum 2005-2010 (read only) / Interfacing / Re: servo/ motor problems on: November 03, 2006, 04:23:09 pm
The link doesn't work.

You don't need a resistor to hook up a servo.
In this presentation you can find instructions for connecting a servo to your arduino:
http://todbot.com/blog/wp-content/uploads/2006/10/arduino_spooky_projects_class3.pdf (page 22 following)

http://todbot.com/blog/spookyarduino/  <---- have a look at all the class notes. Very good stuff for beginners!
59  Forum 2005-2010 (read only) / Interfacing / Re: What USB does Arduino Use?? (USB1.1 or USB2.0) on: November 11, 2006, 04:22:06 am
Well, since RS422 was mentioned I have to add RS485 which allows up to 1.2 kilometers of cable lenght at 100kbit/s (same as RS422 I think) and is quite common, too.

Does anyone have a link for how to build your own RS232 to RS4xx converter?
60  Forum 2005-2010 (read only) / Interfacing / Re: Measuring vibration on: November 08, 2006, 09:42:05 am
Have you seen this:
http://todbot.com/blog/2006/10/29/spooky-arduino-projects-4-and-musical-arduino/
http://todbot.com/blog/wp-content/uploads/2006/10/arduino_spooky_projects_class4.pdf

Whack the piezo to generate a number based on force of whack. Used for a MIDI drumkit.
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