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16  Using Arduino / Project Guidance / Re: Arduino propely booting only if usb powered on: November 07, 2011, 04:11:53 pm
Thnks you all guys for the replies,

I have 6 aa batteries powering the thing. I tried to power on the thing with the lcd unplugged and then plugging it back: everything worked fine. So the problem clearly is the built in regulator,
it can`t take the current surge requested by the lcd (wich is absolutely necessary in this project) on startup.
How can I fix that?? I was thinking to some sort of capacitor on the rest pin of the ardu to reset it a coople of 100/ths of seconds after initial power on but sounds a very rough solution to me, what else should I do, beside using a separate power source for the screen?
17  Using Arduino / Project Guidance / Re: Arduino propely booting only if usb powered on: November 06, 2011, 04:17:44 pm
i just mispelled "it"... "...if I power the arduino via the 9v connector (the "jack" near to the usb connector)"..... any ideas? Im pretty puzzled! the battery I am using is heavy duty so no prob there.... when it is powered via usb does the same power regulator is used as if it were powered by a battery or the voltage is taken straight from the usb? If the second option I may have some excessive load on startup, ie a capacitor in the lcd  smiley-neutral
18  Using Arduino / Project Guidance / Arduino propely booting only if usb powered on: November 06, 2011, 03:20:00 pm
Hi guys, I have an arduino controllinga few leds and sensors + an lcd and it propely boots only if usb powered. If I power it via the 9v connector tit powers up but does not execute any code until i press the reset button. On the other hand if i plug it to the pc it gets up and running immediately and flawlessy. I do not have big loads connected to it (8 leds with proper resistance), why does that happen?!? tnks!
19  Community / Products and Services / PCB printing service for hobbyst (Europe based) on: September 18, 2011, 05:48:59 pm
Hi,
me and a college friend are thinking about starting a PCB printing service for hobbyst, with fair prices and no order minimum (and no crazy prices at all if you order only one board....).
Do you think we`ll be loosing our time or it can be a good idea?

Please give us 45 seconds (or even less...) and fill out this quick survey. Thankyou very much!

http://www.surveymonkey.com/s/5LVB25R


Cheers!
20  Using Arduino / Project Guidance / Re: Change pwm freq. and get a faster analog read on: June 06, 2011, 12:44:37 pm
yep! speed up to between 8 and 16 khz. How to? SOmething I can write in the setup part of the code to do so?

I don`t really get the thing about the analog read, I just know that when i add an analog read in the code the loop slows down about 130us per each analog read.... I ve been told i can make it way faster but idk how to
21  Using Arduino / Project Guidance / Change pwm freq. and get a faster analog read on: June 06, 2011, 10:24:15 am
Hey guys!
I asked a while ago about using Uncle Ardu to handle BLDC commutation, now the project is in its last steps (here http://endless-sphere.com/forums/viewtopic.php?f=30&t=26386 the main topic on EV forum and herehttp://code.google.com/p/dc-brushless-open-source-controller/ on google projects).

Now, I have two issues:


1) the analog read takes way too long. In this quote from the other forum you get an idea of it

 
Quote
no gas reading and no output rewriting: 20 000 ns per loop

gas reading and no output writing: 150 000 ns per loop ===>analo gread is SLOW!

no gas reading but output writing: 60 000 ns per loop

gas reading and output writing: 190 000 ns per loop

target was 40 000 ns per loop to go to 6 000 rpm with a 5% commutation delay

I`m perfectly fine with the output writing time but not with the analog read time. It is ok for first testing but too slow to be implemented every 5 loops or so to do real time current control (curr sensor gives analog value). i`ve been told there is a way to get analog reading way way faster, how to?? 130 000 ns for one analog read is not ok.



2) I need to slow dowm the Ardu`s PWM output to something between 8 and 16 kHz, how to?


thankyou!

PS: the project is open source (Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License), so if you want to join you are welcome!

cheers,
Ludovico


22  Using Arduino / Project Guidance / Re: How to control earphones with the arduino on: April 22, 2011, 05:32:14 am
and since I need thoe earpone just to BEEP can`t i just control them with a fairly small transistor driven by the ardu`s pwm? It doesnt need to be music, it`s just an alarm
23  Using Arduino / Project Guidance / Re: How to control earphones with the arduino on: April 21, 2011, 04:57:44 am
would it be good even with such high impedance earphones?
24  Using Arduino / Project Guidance / How to control earphones with the arduino on: April 20, 2011, 07:42:05 am
hey guys - I need to put the "beep" usually made pluggin a buzzer to one of the arduino`s pwm in a pair of earphones-
How to?

 I don`t think the ardu will make it sucessfully driving 90 and 800 ohms earphones, so I was thinking about using an amplifier. right?
Are there some commercial cheap things you can suggest to me or I have to make my own (VERY) crappy amp?

Thankyou so much  smiley-wink
25  General Category / General Discussion / Nerdy game used by US air force to train pilot`s reflex! on: April 15, 2011, 04:44:14 pm
guys I`m getting hella addicted to this game  smiley-mr-green  And people in my college class too  smiley-twist

http://oneawesomenessaday.blogspot.com/2011/04/awesome-game-how-awake-are-you.html

can you go over 20 secs? can someone make a software that plays at this game?!?!?
26  Using Arduino / Project Guidance / Re: Is arduino fast enough to handle brushless motors commutation?! on: March 30, 2011, 08:36:52 am

I can already read the sensors and control some outputs on Ardu (in my automation engineering class in Italy we sometimes refer to it as God Ardu, who watches you  smiley-lol), my "only issues" were about speed of the whole system, seems there is enough, and how to connect the Ardu`s output to the mosfets.

I am reading http://focus.ti.com/lit/ml/slup169/slup169.pdf wich is great theory explanation about mosfets.
Still, i don`t understant why logic level gate mosfets arent the right solution to "make it easy.. this is the datasheet of those i was looking at... http://www.irf.com/product-info/datasheets/data/irls3036-7ppbf.pdf

Help please  smiley-lol
27  Using Arduino / Project Guidance / Re: Is arduino fast enough to handle brushless motors commutation?! on: March 29, 2011, 04:52:15 pm
I don`t know, anyway looking with the search function in the datasheet I want able to find the word sensor without the word less near to it.
Of course, I may be wrong (and prabably I am!), but I am not really interested in understanding how that ic works, since my main point right now is to understand the principles of how to drive high power mosfets from Ardu and how to choose the mosfets (i can say that the thing about logic level gates in my last post is the main point for me right now). Anyway, thankyou for posting me that datasheet! :-)
28  Using Arduino / Project Guidance / Re: Is arduino fast enough to handle brushless motors commutation?! on: March 29, 2011, 04:32:44 pm
Yep I checked the datasheet and it`s for sensorless commutations, if fact it says something like "you`ll save 3 hall sensors with this lol".

I can already read the sensors and control some outputs on Ardu (in my automation engineering class in Italy we sometimes refer to it as God Ardu, who watches you  smiley-lol), my "only issues" were about speed of the whole system, seems there is enough, and how to connect the Ardu`s output to the mosfets.

I am reading http://focus.ti.com/lit/ml/slup169/slup169.pdf wich is great theory explanation about mosfets.
Still, i don`t understant why logic level gate mosfets arent the right solution to "make it easy.. this is the datasheet of those i was looking at... http://www.irf.com/product-info/datasheets/data/irls3036-7ppbf.pdf
29  Using Arduino / Project Guidance / Re: Is arduino fast enough to handle brushless motors commutation?! on: March 29, 2011, 02:36:52 pm
tnks guys smiley
Tnks for the link also, they refer to great technical works but are pretty different from my goal, I want to make a sensored controller to use on a ebike. I used to run it on a sensorless rc controller, it worked great but with the (big) limit that I had to run it at about 10mph before the back emf was strong enough to make a sensorless controller work.

Is there any ic that can help me connecting a logic pin (arduino output) to the mosfet gate?
 I think I could solve this issue using logic level gate mosfets, but seems I`m wrong  smiley-sad
30  Using Arduino / Project Guidance / Re: Is arduino fast enough to handle brushless motors commutation?! on: March 29, 2011, 11:20:11 am
What about connecting the arduino pwms to the mosfet? I was thinking of useing a "pre-amp" stages made with transistor in order to keep the arduino away from the mosfets` gate saturation current (very high on 400A mosfets) and make a quicker switch. Am I on the right path?


In order to pick the right components i`ll refer to some datasheets and guides from national rectifiers and others.

I have some "ideal assembly" knowledge (part of a college exam), reading datasheets etc i may be able to write the code/part of it in assembler.
If needed i`ll get into it and, eventually, ask for help on the forum if i won't manage to figure it out myself

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