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1  Topics / Science and Measurement / Frequency counter for shortwave radio. on: March 20, 2011, 08:17:15 pm
I have been trying to construct a shortwave radio and I have been having trouble to get the tuning to work.  In order to test my tuning circuit I would like to add an arduino frequency counter that measures in the range of 10-30MHz. 

Is there a way to test these high frequencies with the standard arduino and serial monitor?
2  Forum 2005-2010 (read only) / Syntax & Programs / Re: IF and If Help ranges on: June 16, 2010, 03:40:13 am
ah thank you never thought of double brackets  smiley-grin
3  Forum 2005-2010 (read only) / Syntax & Programs / IF and If Help ranges on: June 16, 2010, 03:20:18 am
Hi, Simple question:

How I create if ranges?

if (something >1 && <10){
//do something here

Its wrong and I have tried many combinations to get it right.

Thanks in advance
4  Forum 2005-2010 (read only) / Interfacing / Re: Upload data to web interface on: August 29, 2010, 05:40:16 am
This looks awesome! Did you write the AJAX and php your self?  Id like to use this for my wind generator and broadband speed, SNR
5  Forum 2005-2010 (read only) / Interfacing / Arduino + GPS Receiver + 3G Modem = Car Alarm on: August 29, 2010, 04:53:14 am
Hi guys,

Not long ago my brother wanted to know if I could make a van alarm that would send a text message to a cellphone notifying that the car had been broken into.

Are there '2g/3g cellphone modems' that you insert a sim into and connect to an arduino's serial pins?  It would have to be able to:
  • Monitor sensors eg reed switch, motion sense, infrared.
  • Monitor GPS coordinates (using arduino gps shield?)
  • Receive text commands like 'activate' 'location'
  • Send status messages + GPS data to user.

Thanks in advance for replies  8-)
6  Forum 2005-2010 (read only) / Interfacing / Re: VHS Data storage on: January 23, 2011, 06:39:43 pm
Ok so vhs video sounds too complicated.

But audio cassette could be possible. Would it be as simple as
-writing a starting byte to indicate a new file
-digitalWriting for a certain amount of time for each. - what type of encoding would be used? Would manchester encoding work or would the timing of each cycle bit be too unreliable based on the speed of the tape?

Im not really sure how the magnetic head works of a audio tape player if if it is simple as using the digital i/o pins to make a 0 or a 1 :-/
7  Forum 2005-2010 (read only) / Interfacing / VHS Data storage on: January 23, 2011, 04:25:30 am
Random thought.

Could it be possible to connect an aduino to the magnetic head of a a vhs tape player to read/write digital data? I know it would be slow but quite interesting inventing something like 'VHSFS' to store files.  smiley-grin
8  Forum 2005-2010 (read only) / Interfacing / Re: Arduino & WRT54GL serial communication on: July 27, 2010, 03:24:16 am
i used the USB version of the arduino.  Are you meaning the reset pin on the RS232 version of the Arduino?  If So i think JB grounds the reset pin in the 232 connector so it doesn't reset when it receives data from the router.

Im am not sure of this because i haven't got a rs232 serial arduino :-/.  I reckon it's easier to use the RX/TX pins on the ardino and convert the logic voltages TTL. (if your board has TX/TX pins)

a few random notes:

the router speaks it's TX/RX logic signals at 3.3v aka 3.3TTL
the arduio speaks its TX/RX logic at 5v (this is a problem) aka 5vTTL
the serial arduino is completly different type of serial communication aka RS232

If you are trying to connect the RS232 Seial version which it seem you are (its what JB did) Youll have to use a MAX232 IC to convert arduino's RS232 logic into Router 3.3vTTL logic.
9  Forum 2005-2010 (read only) / Interfacing / Re: Arduino & WRT54GL serial communication on: July 27, 2010, 02:22:56 am
What wires did you mix up that caused the router to be cooked?
Did you remove the auto reset feature of the Arduino? How?

I simply tried to connect the router to a 12v sla battery (since you can't plug it in) and got confused with the wiring diagram since it was in black and white!

Positive was negative negative was positive   :-/
10  Forum 2005-2010 (read only) / Interfacing / Re: Arduino & WRT54GL serial communication on: July 27, 2010, 12:22:15 am
yep i got it going great - untill i cooked the wrt54GL by putting the wires round the wrong way. (stupid me) smiley-sad

But however before that happened it was running well  smiley-grin

How it worked:

R/C car contains a chip commonly known as  RX2 chip.  If you have a car you simply get the datasheet for the pinouts of the car driver IC and solder the forward, left, right etc wires on top of the pins and connect them to the arduino. (A digitalWrite HIGH to a pin will make it do what ever its soldered to).

To get the communication going I used the Logic Level Converter between the TX and RX (a TX on the arduino goes to the RX of the router and vice versa).  I had a little trouble at first but turned out I had the converter round the wrong way. Once fixed i could use JB's code without making any changes. ;D

Hope that helps smiley
11  Forum 2005-2010 (read only) / Interfacing / Re: Arduino & WRT54GL serial communication on: June 14, 2010, 06:21:53 am
thanks for the replies smiley I have come to the conclusion that both the arduino and the wrt54gl use Transistor-Transistor-Logic NOT rs232 and therefore the only thing that needs to be changed is the voltages between them.

Im guessing that you would only want to use a MAX232 to communicate with a PC... or the serial version of the arduino.

So i guess that this will do the trick: Logic Level Converter sku: BOB-08745. From sparkfun electronics.

I hope that summerises it up smiley-wink

12  Forum 2005-2010 (read only) / Interfacing / Arduino & WRT54GL serial communication on: June 14, 2010, 03:43:11 am
Hi all,

Today I got a WRT54GL and I'm a little unsure about getting the serial on the router to communicate with an arduino.

Can I used a  MAX232 to convert the routers 3.3v Logic to the arduino's logic?

I really don't understand RS232 and how it works and if that has anything to do with the arduino's RX/TX pins.

i found this diagram that is used with a pic that they used

I would really appreciate any help so i know if a MAX232 is the way to go.

Thanks in advance
13  Forum 2005-2010 (read only) / Bar Sport / Re: Why are DIPs so inneficient compared to SMDs? on: June 14, 2010, 03:21:39 am
cheap as chips... i wish
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