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46  Using Arduino / Microcontrollers / "[...] please define PAGEL and BS2 signals" (ArduinoISP + ATiny85 problem) on: June 29, 2011, 03:17:56 pm
I'm having mixed success using the ArduinoISP sketch to program an ATiny85. It works, but with errors. The sketch transfers and is subsequently running on the Tiny, but I'm getting error messages from avrdude all the same. See below and attached screenshots for additional info.

I have searched the forum, but only found dated threads on this topic. Hoping that someone here might shed some fresh light on it. As most of my projects are quite limited, the prospect of moving to a cheaper and simpler microcontroller is very compelling.

The setup
I'm using the Arduino 022 IDE together with an Seeeduino with the standard ATmega 328.

The IDE has been upgraded with the Arduino Tiny cores from http://code.google.com/p/arduino-tiny/ and the installation seemed to work out just fine. I have also enabled the ATiny85 in the boards.txt file according to instruction.

To get the programmer going I have followed this guide mainly: http://provideyourown.com/2011/arduino-program-attiny/ together with http://arduino.cc/en/Tutorial/ArduinoISP, but added some tweaks I picked upp on the way from misc. threads in this forum and on the internet. Main resources used for tweaks:
- http://arduino.cc/forum/index.php/topic,65099.0.html
- http://laclefyoshi.blogspot.com/2011/01/note-of-caution-for-arduino-isp.html

Using only the two main guides did not yield any working configuration. In the end I have ended up with the following:

ATiny85 pin --> Arduino pin
1 --> Digital 10
4 --> GND
5 --> Digital 11
6 --> Digital 12
7 --> Digital 13
8 --> 5V

Additional connections
- To prevent the auto reset, I have a 120 Ohm resistor from 5V to RST on the Arduino.
- To test the Blink sketch on the Tiny, I have a 330 Ohm resistor and an LED on ATiny pin 5 (digital 0) to GND.


The problem
As mentioned above, the sketch transfers and starts executing (The LED on ATiny pin 5 starts blinking as expected), but I'm getting errors from avrdude saying:

Code:
Binary sketch size: 748 bytes (of a 8192 byte maximum)
avrdude: please define PAGEL and BS2 signals in the configuration file for part ATtiny85
avrdude: please define PAGEL and BS2 signals in the configuration file for part ATtiny85


The question
What have I done wrong? Any clues welcome.



Thanks!/Anders




47  Using Arduino / Project Guidance / Re: Which platform to use, question of voltage, current, plus SPI question... on: June 14, 2011, 10:47:27 am
For battery applications, you can seriously extend the battery lifetime by using the sleep modes in the AVR chip. Wakeup on internal watchdog or external pin interrupt.

See http://donalmorrissey.blogspot.com/2010/04/putting-arduino-diecimila-to-sleep-part.html
and http://interface.khm.de/index.php/lab/experiments/sleep_watchdog_battery/

48  Using Arduino / Project Guidance / Re: Bioelectrical Impedance on: June 13, 2011, 04:06:44 pm
Ok,
again, I am no expert, but I notice you use the term "impedance" instead of "resistance", so that to me would give a clue to the 4-connector, vs. 2-connector question you had.

2 terminals = resistance
4 terminals = impedance (real + imaginary part)


Impedance also suggests alternating current (AC) to me. Are you planning to tap your measurement reference signal directly from the grid? Although I agree it is probably accurate enough, it is not healthy to send that amount of voltage and current through your subjects. You need to drop it down to under 110V I guess, probably under 70V to be withstandable by the subjects.

I would also worry more about the algorithm. Once you have your reading, how do you tell fat content from muscle based on that?

49  Using Arduino / Project Guidance / Re: Bioelectrical Impedance on: June 13, 2011, 03:27:15 pm
Very interesting project! How would it be connected to the user (feet+hand, hand+hand, ...)? What algorithm had you intended to use for the calculation, once you've got your reading?

I'm no expert, but I would say that generally, the Arduino is not a small current, low voltage device. I would be bolder in voltage/current output to get more reliable readings. As long as it is not fatal, but only stinging/buzzing for an adult you should be fine. Just put a visible disclaimer on the device and make sure it does not look "professional" so that no one can claim they were fooled by the looks of it.

50  Using Arduino / Project Guidance / Re: Maglev baby cot? Feasibility question. on: June 07, 2011, 12:18:00 pm
Oh!,
I didn't realize that it would be loud! Definitely thought it would be silent. I have no experience at all from working with coils and magnets. Didn't realize they make any sound meanwhile.

I guess I'll just store away this idea for later reuse in some other shape or form.

Thanks for the feedback!/Anders
51  Using Arduino / Project Guidance / Re: Maglev baby cot? Feasibility question. on: June 07, 2011, 08:04:22 am
Indeed! :-)

It's hard to describe without a proper sketch, but it would allow for a rotational "rocking" movement by the way it is attached to the loops, but it would at the same time prevent the whole cot from just floating away and falling off the magnetic cushion.

52  Using Arduino / Project Guidance / Re: Maglev baby cot? Feasibility question. on: June 07, 2011, 07:57:45 am
Good points.

My wife is already a little bit of a suspicious towards my Arduino hobby. Adding our baby into the mix will indeed be a complicating factor. I was however thinking about introducing some kind of guide mechanism to make sure only up/down movement would be physically possible. Something like two poles at the short ends, with rope or wire loops around them to prevent lateral movement.

53  Using Arduino / Project Guidance / Maglev baby cot? Feasibility question. on: June 07, 2011, 07:35:30 am
Hi,
while shopping for some minor magnets the other day for my balcony windmill project I realized there are some quite powerful magnets that are not too expensive and the idea of a building an Arduino maglev baby cot for my newborn child came to mind.

There are several pages describing solutions based on a magnet, coil and an hall effect sensor. The most serious treatment I've found however states that whatever you build will be inherently unstable (http://mekonik.wordpress.com/2009/03/17/arduino-magnet-levitation/). I don't want my baby to be tipped over and thrown out of the cot in mid air. The idea is to have her floating comfortably of course, maybe with some gentle rocking to promote sleep.

I am also a little bit worried about exposing my baby to strong magnetic fields for extended periods of time on a regular daily basis.

So I have two questions I guess.

1 - Is it possible to build a stable solution?

2 - Can the magnetic fields involved pose any health hazard to small babies?


I was thinking about magnets like these:

56kg
http://www.supermagnete.de/eng/Q-60-30-15-N

100kg
http://www.supermagnete.de/eng/Q-51-51-25-N


Any thoughts and input appreciated of course!

54  Using Arduino / Project Guidance / Re: Small balcony windmill to power Arduino (or ATtiny85). Feasibility? on: June 05, 2011, 02:01:28 am
Ok,
thanks for all the input and pointers. As usual, I got some new angles that I hadn't thought of before hand.

Several challenges for me as a newbie in this one. No idea how to trigger the discharge of the capacitor when ready for instance, but I guess that will be a specific topic for later.

Thanks again!

//Anders
55  Using Arduino / Project Guidance / Small balcony windmill to power Arduino (or ATtiny85). Feasibility? on: June 04, 2011, 04:28:38 pm
Hi,
I'm looking for some early inout and feedback on a project I have been thinking about lately. See below for background and questions. Your input would be very welcome.

The idea
I'm thinking about building a small windmill on the balcony to power my arduino, or (better) an ATtiny85. The idea is to collect energy from the windmill and store it in a capacitor. When the capacitor is full, it will somehow discharge and power the microcontroller which does some kind of computation (still to be defined what, but let's say blink an LED).

The approach
My basic idea is to glue magnets to a disc and have them rotate over some coils to generate electricity when the wind turns the mill. The electricity will go into a bridge rectifier and then into the capacitor as described above.

To get me started I already bought these
- Bridge rectifier
http://www.kjell.com/content/templates/shop_main_details.aspx?item=90050&path=239000000,266000000,268000000
- 4 x Ring magnets
http://www.supermagnete.de/eng/R-15-06-06-N

I also have a 5V super capacitor lying around somewhere.

Questions:

A - Is this feasible?
Is there a better way to do this? General thoughts?

B - What kind of coils and how many should I use?
1 coil? 2 coils? 4 coils? How should I hook them up to the rectifier? Where can I source the coils? Make myself? How?

C - Any pointers to similar projects?
I did some naive googling, but didn't find anything useful. I bet I'm not the first though. All/any pointers welcome

Thanks/Anders
56  Using Arduino / General Electronics / Re: Correct calculation of resistor value when connecting LED? on: May 28, 2011, 12:16:12 pm
Thank you all!

Very good and enlightening answers and explanations!

This is such a great forum, made up from a lot of great people. When I gain more experience, I'll make sure to pass the spirit on.

Thanks again!

 
57  Using Arduino / General Electronics / Correct calculation of resistor value when connecting LED? on: May 27, 2011, 01:55:31 pm
Hi,
this is a newbie question, but I would really appreciate some help or indication if I am thinking about this in the right way.
I have actually studied digital electronics, but my memories are very vague and I am much more of a software guy nowadays.

My question:
How do I calculate the correct value for the resistor when connecting an LED from 5V to a digital pin on the Arduino?

Background:
Many examples either just short circuit from 5V over the LED to the pin, or say something sweeping like "... any resistor between 330Ohm and 2KOhm should do the trick". I have a feeling that the first is not really best practice and that there is a proper way to come to the second conclusion.

So, I know the basic formula V=R*I.

In this case I guess we have:
V = 5
R = (to be calculated)
I = ? (what should I plug in here? 0.55A?, The max source current of the Arduino?

So, two more questions arises:
- What current do I calculate with?
- Do I need to take the forward voltage drop of the LED into consideration?



Any help would be much appreciated!
58  Using Arduino / Project Guidance / Re: water depth measurement on: May 20, 2011, 02:36:00 pm
I agree with that. My current take on it is to give the the loop a lot of room around the wire/guide so that it cannot really get stuck, but it's not optimal.

I'm thinking there must be a "standard solution" to this problem which is really easy to build, but I haven't found one yet, but I'm just starting to think about it and looking around.

Any ideas?

/Anders
59  Using Arduino / Project Guidance / Re: water depth measurement on: May 20, 2011, 02:26:43 pm
I'm having a similar challenge, where I want to prevent a water pump from activating below a certain water level. Like you, I want something reliable and dead simple to make sure the pump doesn't run dry (and burns as a result).

I have been toying with the idea of using either a magnetic reed switch of hall effect sensor attached on the outside of the tank and than have a magnet attached to a cork float up/down guided vertically by a wire or something anchored to the bottom of the tank.

Maybe you could use something similar, with four sensors or magnetic reed switches?

Have yet to try it myself though.

Good luck!/Anders   
60  Using Arduino / Programming Questions / Re: edit sketch on: May 12, 2011, 10:27:34 am
Exactly!, and if you really want to go fancy, you could perhaps display the delayPeriod value on an LCD, bolt the pot and the LCD onto a nice box, stick the the Arduiono in it and you've got yourself a neat control panel.

:-)

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