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106  Forum 2005-2010 (read only) / Frequently-Asked Questions / will EEPROM keep values after reprogramming? on: August 31, 2009, 03:04:38 am
Hi,

If I write values to the atmega's EEPROM, can I read them after I have reprogrammed the chip with another program more designed for reading and printing the eeprom values?

Joachim
107  Forum 2005-2010 (read only) / Frequently-Asked Questions / serial232 gets hot! on: August 31, 2009, 01:10:39 pm
Hi,

I followed the tutorial on how to connect a max232 to arduino. The 232 chip gets quite hot. It's not melting or anything, but is this normal?

I also noticed that the cap from v+ is missing on the tutorial. Is this not necessary?

Joachim
108  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: most simple arduino on: August 28, 2009, 03:13:43 am
Thanks again, this solved the issue. I had some oscillators lying around, and when i cut the 22pF caps and replaced the crystal with one of these, it worked just fine.

Thanks again!

Joachim
109  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: most simple arduino on: August 28, 2009, 02:01:30 am
Before the newly ordered scope is in the mail (!), I have another question: Is the distance from the crystal to the 22pF caps of importance? The board itself is not very big ( smaller than the 2009), but very crowded. The caps are probably two inches away from the crystal.

Joachim
110  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: most simple arduino on: August 27, 2009, 03:01:03 pm
Thanks, I needed that in writing. I wil now show my wife...

Joachim
111  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: most simple arduino on: August 27, 2009, 09:04:01 am
Thanks for the quick replies.

The chip is working and can be programmed by any other working board. The 16MHz crystal has its 22pF caps. How do I check if the crystal is oscillating?

Joachim
112  Forum 2005-2010 (read only) / Frequently-Asked Questions / most simple arduino on: August 27, 2009, 08:06:24 am
Hi all,

I have made two different boards, one is working when powered off the ftdi cable, one is not... So the question is what is the most basic arduino one can make when powered from an ftdi cable? I have the reset cap (and pullup) and vcc, gnd, tx and rx. the chip has crystal an caps for it. Do I need a decoupling cap with my setup? i have room for it, but I don't have the cap on hand. It is also only on the regulator side of the power selection, so it won't come into play when the jumper is set on usb power. What am I missing? There is 5v where it should be, but even preprogrammed chips won't flash my led, so the chip can not be working with my setup.

Joachim
113  Forum 2005-2010 (read only) / Frequently-Asked Questions / Anyone know of IP65 or equivalen rocker switches? on: August 07, 2009, 08:13:21 am
Hi again,

I heve found some of these IP65 rocker switches, but they are so large they completely fill up the interior space in my waterproof box. I am looking for smaller swithces with a rating of IP 65 or better. Does anyone know of any?

The ones I found are these:

https://www1.elfa.se/data1/wwwroot/webroot/Z_DATA/03504669.pdf

Joachim
114  Forum 2005-2010 (read only) / Frequently-Asked Questions / atof returning a different floating value on: June 10, 2009, 04:10:47 am
Hi,

I'm making an application to use GPS input to calculate distances for use on the golf course, and therefore I have been playing with parsing nmea data. However I have discovered that if you convert a string like 3.14 to a double value and convert this into to integers (one for the integer value and one for the decimals, it returns 3.13.

Why is that?

Code:
char str[] = "3.14";
int piR = 0;
double piD = 0;
int dec = 0;


void setup(){
 Serial.begin(4800);
  }
  
void loop(){
  piR = atoi(str);
  piD = atof(str);
  dec = 100*(piD-piR);
  
  Serial.print(piR);
  Serial.print(".");
  Serial.println(dec);
  delay(1000);
}  
115  Forum 2005-2010 (read only) / Bar Sport / Re: Charging using 120V power supply in Europe? on: July 17, 2010, 03:48:57 am
Based on what I read in and between the lines, I would not do there! Chargers are usually made with current limiters in order to protect the battery. Your charger is made to work with your helicopter, and if you are not exactly sure what you are doing,you risk damaging your toy. A voltage converter on the AC side is much simpler and safer.  They should not cost too much, as they basically consist of a transformator.
116  Forum 2005-2010 (read only) / Bar Sport / Re: Problems with Max1811 Li-Ion Charger IC on: February 24, 2010, 03:58:17 am
Hi,

Check the answers here: http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1252925145/11. The power regulator could have problems supplying 500mA over time. That may be the issue.

Joachim
117  Forum 2005-2010 (read only) / Bar Sport / Re: Cheapest PCB Fab for small qty? on: November 09, 2009, 06:15:11 am
I have only used BatchPCB, they are not that expensive but they take some time. But my experience is that if you order one pcb, you get two.

118  Forum 2005-2010 (read only) / Bar Sport / Re: Mathematical question on: September 15, 2009, 02:13:05 am
I wasn't that far off, I had to check
http://hyperphysics.phy-astr.gsu.edu/Hbase/mot.html

and they calculated the same acceleration.

Joachim

119  Forum 2005-2010 (read only) / Bar Sport / Re: Mathematical question on: September 15, 2009, 01:59:34 am
It's not stupid to forget, we are all getting older and filling our heads with other things... If you solve X=v0*t + 0.5*a*t^2 with the values you give, you will get 0.16667 m/s^2. But don't blame me if I'm wrong, it's been a while for me as well...

Joachim
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