please stop ure emails or provide an opt-out, ray k

From: Drew Fustini <messages@element14.com>

To: raykeith7 <raykeith7@yahoo.com>

Sent: Tuesday, May 17, 2011 9:41 AM

Subject: - Re: Have a question about Arduino? Ask me! [7v37o7-7su-ogy]

Re: Have a question about Arduino? Ask me! created by fustini in Arduino - View the full discussion

Happy Brirthday!  And it was awesome to hear you on my most favortist podcast in the whole wide world, the Amp Hour!

My question is: any DIY projects that you were itching to do but couldn't until you were 21?

Cheers,

Drew

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Hi,

Wanted to tell you how much I loved your video tutorial series. I've been involved with industrial robotics for several years and just started playing with the Arduino for a hobby project here recently. I am still a bit new to this controller and the programming but have picked up a lot very rapidly, thanks in part to your excellent tutorial videos... but, on to my question...

I am trying to use the Arduino Uno to control servo motors via a bend sensor. The sensors are extremely sensitive (~400ohms to over 200Kohms with a 45° bend) I have been using this sensor across the 5v supply using a pulldown resistor as my analog input but the servo jitters and does not hold any particular position very easily and the movements are large and jerky. I am trying to reduce this using hardware (resistors, wheatstone bridge) and some programming but have not had much luck so far. I am also trying to set a stable midpoint for the servo with the bend sensor giving a smooth (or at least smoother) response for back and forth movement. This is basically for a spine type robot in two sections with one servo controlling up/down and one for left/right on each section with one bend sensor per servo. Any ideas on what to try next?

Hi Jeremy

I'm not an Electronic Engineer so struggling here. I would like to use my Arduino to generate some Wiegand compliant logic signals as an output. So not sure if I should use Digital IO's or Analogue or otherwise (I2C SPI?) and whether I need one or two IO ports to do it. Assuming you're not acquainted with Wiegand, here is my take.

You require two data wires (Data 0 and Data 1). Both are default high at 5V (max 1mA). Having seen your tutorial on I2C (very good by the way) I'm assuming I need somewhere some pull-up resistors (or do I). The Wiegand operates using 26 bit code to transmit the data. This code is generated using the two wires (without a timer clock). Thus if you want to generate a data bit "1" you open the Data 1 line to generate a 0V pulse and similarly for your data bits with zero binary value you use the Data 0 line. The standard is particular about the timings of these (square wavish) pulses. The data pulses for the Data One and Data Zero shall not overlap or occur simultaneously. Pulse Width Time should range from 20microseconds to 100

microseconds and the Pulse Interval Time should be anywhere from 200microseconds to 20milliseconds.

Is this readily done. I'm assuming that one will always need a microcontroller to convert any input - say a mobile phone number or a keypad pin code or any unique identifier and convert this into 26bit format and then send this to my Wiegand signal generator to send the code.

Any help gladly appreciated.

The amp hour was a ton of fun.  Thanks for the birthday wishes!

You can opt out in your account preferences.

Try implementing a moving average in software - with a large enough window size, you should have no problem smooting the movement.

Yes you should be able to write a library for the arduino to accomplish this - It should probably be done in actual C code for efficiency.  I'd start by taking at a look at the I2C library source files for hints.

Dear Jeremy,

I am a novice in electronics, but with great learning skills. I need to make the following project for which I need your help: using a HMC5843 or other recommended compass chip, I need to came up with this chip connected to a battery and to a lcd screen (as small as I can get from the market) on which to be written only 4 digits: 222 d (degree) or whatever is the mommentum direction. Can you please give me feedback on this? Thanks in advance!

Attila

Hi Jeremy, my questions are two: How to slow down servo motor (I'm using that code)

val = analogRead(potPin);                
if(val>300){                             
  myservo1.write(90);
  
}else{                                  
    myservo1.write(180);
}}

And second:

how to add delay for the last two servos only,here's the code:

if(val>300){                          
  digitalWrite(ledPin, HIGH);          
  digitalWrite(ledPin1,LOW);          

  myservo1.write(90);
  myservo2.write(90);
  myservo3.write(90);
  myservo4.write(50);
  myservo5.write(50); 
}else{                                   
  digitalWrite(ledPin, LOW);
   digitalWrite(ledPin1, HIGH);
  myservo1.write(180);
  myservo2.write(180);
  myservo3.write(180);
  myservo4.write(0);
  myservo5.write(0);  
}}

servos 1-3 going at the same time, S-4 and 5 with delay

Thanks in advance!

Instead of using an LCD display, you might be better off with a few 7-segment number displays.  You can use a simple shift register to control each one.