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46  Using Arduino / Sensors / Re: Is there a voltage regulated, level shifted I2C bus solution for AA powered unit on: August 16, 2014, 07:12:00 pm
@EKMallon, wow, quite a story! I'd say that's a good start on a book about the project. I'm curious about the total amount of data logged. It sounded like the 30-minute interval was maybe longer than optimal. What would a better interval be, and how many bytes of data are logged for each interval?
47  Using Arduino / Project Guidance / Re: USI Clock on: August 15, 2014, 07:31:32 pm
Toggling the clock is done by code, so the speed is dependent on how the code is written. I wrote an SPI library a while back (here) and estimated the clock speed to be about 1/10 of the system clock. Unrolling the loop should give a bit of improvement over that. There's also an example in the datasheet.
48  Community / Local Groups / Re: local group in Windsor, Ont or Detroit MI on: August 13, 2014, 06:29:23 pm
Hi, I'm in Shelby Township, near Utica Michigan.
Any action around here?

Howdy. I recently joined a new group in Flint, there have just been two meetings I think.  I also joined this group but have not attended a meeting yet. Duckie58 and I get together on an irregular basis.
49  Using Arduino / Project Guidance / Re: Arduino Oscillator on: August 12, 2014, 04:35:57 pm
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Not usually. The oscillator is very low power, most scopes will load it  too much and either make it erratic or stop it completely.
Well I can on my 45 year old scope.

Don't make 'em like they used to eh smiley-wink

Is it important to use the right pin? XTAL2 is the oscillator output, so that might be the best one to measure?
50  Using Arduino / Project Guidance / Re: Arduino Oscillator on: August 12, 2014, 04:30:57 pm
i tried  this , but measuring 1/16  of the real signal  its not enough for me as i need to measure  the whole range , and using timers will only get me to 8Mhz max . (am i right?)

What "whole range"? The clock is a single frequency. Are you saying that 1 ppm isn't good enough? You must have some fancy test equipment. Slide-rule accuracy is usually good around here, haha smiley-grin  And yes, a timer will only get to half the system clock because it's toggling the output pin.
51  Using Arduino / Project Guidance / Re: Arduino Oscillator on: August 12, 2014, 02:08:44 pm
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can it be done?  How can i do that ?
Just probe on the crystal with the oscilloscope.

Can this be done just by that? , because i tried that and the signal was erratic varying from 10 hz to 35 khz or so . Am i  connecting the probes wrong?

Not usually. The oscillator is very low power, most scopes will load it  too much and either make it erratic or stop it completely.

Try this sketch, it will output a square wave on pin 11 that is 1/16 the system clock frequency, so 1MHz.
52  Using Arduino / Networking, Protocols, and Devices / Re: Problem in Xbee Communication on: August 12, 2014, 10:38:45 am
Here is a demo I recently did, it uses a potentiometer attached to one Arduino to control a servo on another Arduino. It uses XBee ZB (S2) modules, but in API mode.
53  Using Arduino / General Electronics / Re: Wiring Arduino Micro with Xbee Radio on: August 12, 2014, 07:54:53 am
AVR HW serial idle; RX is INPUT and TX is HIGH
AVR SW serial idle; RX is PULLUP and TX is HIGH

Yeah I found that too, software serial got me to wondering. I don't use it much, haven't had a problem with it, but I've never used it with XBees (I use API mode and that just sounds like a bad combination). Not sure why SWS wouldn't mimic HWS in that regard though.

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I wonder if a PNP transistor with the XBEE and a resistor to the grid switching the PULLUP to ground or not.....?  
Would be cheaper and a bit more static resistant.

PNP should work, meh.

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7407s are old school, I'd bet it's hard to even find one. Use 74HC4050, 74HC125, etc.

How much current can I safely level with those? It looks like 10mA or less.
For signal, fine I guess but I won't be powering an SD on that. Maybe the choice there is a divider.

The IC is a much better choice. It's fine for the SD signals, everything is CMOS so very low current. Not used for the supply voltage of course.
54  Using Arduino / General Electronics / Re: Wiring Arduino Micro with Xbee Radio on: August 11, 2014, 08:52:56 pm
Oh my LULZ! I went back to make sure and this is The Thread where I first saw the diode trick!
See reply #3.

Yes? Is there a question here?

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Question to me is can calling the constructor with inverse_logic as 1 work or would that mess up TX?
I am definitely going to buy a couple dozen 2N7000's and a dozen SN7407's (and some more resistors).

Neither turning the pullup off nor inverting the logic will fix the overvoltage situation. Inverting the logic will definitely mess up communication unless the XBee can also be inverted (I haven't checked), or an inverter is placed in the line.

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The 7407's look like just the thing for leveling hand-rolled SD adapters... there are 6 lines needing leveled, IIRC.

7407s are old school, I'd bet it's hard to even find one. Use 74HC4050, 74HC125, etc.
55  Using Arduino / General Electronics / Re: Edging your DIY PCBs on: August 11, 2014, 07:37:00 pm
Don't breathe this!
56  Using Arduino / General Electronics / Re: Op Amp Hilarity on: August 11, 2014, 07:35:33 pm
And then there is (or rather, was)

57  Using Arduino / Project Guidance / Re: reading 1000ths of a seconds from a pcf8583 rtc on: August 11, 2014, 05:18:49 pm
you have lost me am reading about prescaler but all double dutch will need to improve my knowledge further.

Timers are pretty neat, and even fairly straightforward once you get them figured out a bit.

There's a tutorial here that really helped me get started:
http://www.fourwalledcubicle.com/AVRArticles.php

And of course Nick Gammon's site:
http://www.gammon.com.au/forum/?id=11504
58  Using Arduino / Project Guidance / Re: reading 1000ths of a seconds from a pcf8583 rtc on: August 11, 2014, 04:53:38 pm
so am I right in thinking the best timing a arduino can do is 4 microseconds then.

Given a 16MHz system clock (Uno, et al.), one clock cycle is then 62.5 ns. The internal hardware timers can be configured to count at this rate. Of course there are tradeoffs (e.g. the counter will overflow rather quickly, being only 8 or 16 bits). The input capture unit can be a nice approach in many applications. Basically an external signal causes the current timer count to be captured in another register, and this event can trigger an interrupt, etc.
59  Using Arduino / Project Guidance / Re: reading 1000ths of a seconds from a pcf8583 rtc on: August 11, 2014, 03:57:42 pm
this is the code I am using it flops over at 60000000micro's later but it flops at 60000004micro's later??

can anyone explain it?

Sure can, read this, third sentence:
http://arduino.cc/en/Reference/Micros

PS: Also note that micros() returns an unsigned long, so variables like starttime, timeout, exittime should also be unsigned long.
60  Using Arduino / Motors, Mechanics, and Power / Re: Wiring Arduino Micro with Xbee Radio on: August 11, 2014, 03:48:35 pm
Hello,
I will like to know if there is a way to lift a person with arduino. If there is which arduino & which motor should I use? Would I need a battery? What RPM will I need to reach?

Thanks,
David

Hi David,

You should probably create a new post, and probably in a different forum section. As a reply in this thread, it is way off-topic. First, please have a look at this for some tips. Take special note that a post should not be made in more than one section of the forum.

I'm sure that what you want to do is possible, but your inquiry is too broad to say much more so I might either narrow it down, or explain more about what exactly it is you are trying to do. For example, probably pretty much any RPM will work, depending on how much of a hurry you are in and what gear reduction is available.

Welcome to the forum.
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