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!

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

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!

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

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

 

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

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

would it be good even with such high impedance earphones?

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 

guys I`m getting hella addicted to this game    And people in my college class too 

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?!?!?

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  ), 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 

[i can say that the thing about logic level gates in my last post is the main point for me right now]

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! :-)

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  ), 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

tnks guys
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 

[?]

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

[Each mecahnical rotation is made of 4 electrical rotation, and each rotation is made of 6 state changes. (each state change is the change of TWO pwm output status)]

Hi guys!
I`m making a BLDC motor controller and I am thinking about using Arduino to control it.
It` s very simple, depending on the digital input from 3+1 sensor it has to properly control 6 mosfets. (reads the gas potentiometer once in a while and then applies a pwm signal to 6 mosfets, depending on the readings of 3 hall sensors. Very simple process, based on a Boolean logic that relates hall imputs to phase commutations.)

The question is: Is arduino fast enough for that?!
The motor will be spinning at max 5000 rpm, wich is about 85 rpSecond.
Each mecahnical  rotation is made of 4 electrical rotation, and each rotation is made of 6 state changes. (each state change is the change of TWO pwm output status)

So, 24 commutations * 85 revolutions is 2040 operations per second. Is Arduino with its 16000000 Hertz able to handle that?

A quick math says it has something like 7500 clock cycles for each commutation, but in order not to loose sync the delay of each commutation should not be over let`s say 3%... 
That means not over 250 clock cycle to read 3 digital sensor status, perform a supereasy boolean thing and set two pwm write. Can Arduino handle that?

Thankyou so much!