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16  Using Arduino / General Electronics / Re: Current rating on datasheet.. per channel or total? on: August 14, 2014, 01:09:50 pm
As
Absolute Max Ground Current (IGND) ...................................... 3A
I'd say you'd have to split that among the 8 outputs.
As the maximum current shown in the tables is 350mA, you become the test pilot for higher currents.
What are you planning for source voltage? 5V? 12V?

Be careful. Since the circuit is a source driver array, IGND is mainly the sum of the currents thru the protection diodes, not thru the drivers.

Anyway, most of the time, the sum of the maximum currents thru output pins is less than the maximum currents thru the power supply pins.

  I still say the datasheet is still incomplete. Total device power dissipation will also be effected at the specific output voltage being used and the total device power dissipation will be different at different voltages.

The datasheet statement of:

Quote
These drivers can manage multiple loads of up to 50V and
500mA, limited only by package power dissipation.
Without stating the limit in wattage is incomplete.
17  Using Arduino / General Electronics / Re: Current rating on datasheet.. per channel or total? on: August 14, 2014, 12:20:36 pm
The datasheet is rather incomplete ( limited only by package power dissipation ) as it doesn't list the maximum power dissipation specification, so your question can't be answered without it. I'm pretty sure that package maximum power dissapation would be the limiting factor if all outputs were trying to supply 500 mA each, but again the specification needed is not provided.


18  Using Arduino / Microcontrollers / Re: Arduino how to burn bootloader into other chips on: August 13, 2014, 10:40:57 pm
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* Connect the ISP burning port of Arduino Duemilanove to UNO’s burning port via Dupont line.


 That can't be correct. The target's reset pin on the target's ICSP connector must wire to a digital output pin on the 'programming uno' board. Wiring reset pin to reset pin is not going to work.

19  Using Arduino / Sensors / Re: Question re: Accuracy of Reference re: Accuracy of ADC on: August 13, 2014, 09:11:41 pm
Quote
That is, the high-accuracy reference would be mostly useful to reduce calibration requirements since its initial accuracy would be much better than that of the voltage reference in the MCP3910?

I would use the word more-accuracy rather the high-accuracy, as high is subjective and relative to some unstated standard. In a typical ADC converter there are two most important attributes that dominate it's 'accuracy', bits of resolution (step size) and reference voltage accuracy. And lastly even with 'high-accuracy' ADC one may very well still require (or want) a automatic or manual calibration function, as the signal being measured from some sensor may not have a 'perfect zero' and require at least an offset correction. And if you have a calibration function anyway, then absolute voltage reference is not as important as long as it has good stability specs.

 True accuracy is a very complex subject if and when wants to dive down into it, in fact there is a whole field called Metrology that deals with the subject.  http://en.wikipedia.org/wiki/Metrology
 

20  Using Arduino / Sensors / Re: Question re: Accuracy of Reference re: Accuracy of ADC on: August 13, 2014, 07:49:43 am
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Thus, the error of the reference is so consistent that it can be calibrated out of existence?

 Yes. If the ADC exibits good 'repeatablity' then any constant variation of the reference can be compensated in software, either initially or as part of a automatic or manual calibration function.

21  Using Arduino / Project Guidance / Re: Servo wont work with digital read on: August 13, 2014, 07:37:40 am
Switches wired correctly to prevent 'floating input', via external pull down resistors? Best way to wire switches is to enable internal pullup resistor and wire switch between input pin and ground, reading LOW then = switch pressed.

22  Using Arduino / Project Guidance / Re: 4 Servos w/ Nano -- Help Please on: August 12, 2014, 01:28:42 pm
Most likely a power problem. If you are trying to power all 4 servos from the Nano's 5 volt pin then there will just not be enough current to support that. An external +5vdc voltage source rated at a minimum of a couple of amps or 4 series connected AA alkiline cells should work with your small servos. Be sure the external voltage source's negative terminal is wired also to an arduino ground pin.

23  Using Arduino / Project Guidance / Re: need to drive a zero centered meter on: August 11, 2014, 05:56:27 pm
You can do that with two PWM pins connected to the meter terminals.

If you set a LOW on one pin and output PWM on the other, current will flow in one direction. Reverse the pin settings to have the current flow in the other direction. Since LOW is not 0 V, you will probably need to calibrate the PWM settings to get the meter deflection you wish. You may need a resistor in series with the meter to limit the current.

Ok I'll byte,, ok so I have 2 pcm outputs and you need a ground so "who is on first"?? smiley-roll-sweat
do you mean hook one output to one side of the meter and the other output to the other side????
or do you mean hook both outputs to one side and ground the other???
~~Cris

No ground needed. Just two pwm pins, one series resistor most likely, wired to the two meter terminals, and some 'fancy coding'. Things you need to know or find out is what the full scale deflection current rating of the meter is for both directions from 'center zero'. As in perhaps it's rated as -1.0 mA to +1.0 mA?





24  Using Arduino / Project Guidance / Re: Nano stops running and flashes the power LED rapidly... on: August 11, 2014, 09:51:33 am
Coding can have no effect on the power LED, so there has to be a power problem at the root of this symptom. How are you powering the nano?

25  Using Arduino / Programming Questions / Re: Pro mini programmer on: August 07, 2014, 12:55:58 pm
That is not a Arduino 'programmer' as it is not a ICSP programmer but rather it's a FTDI based USB serial converter. As such it will work to upload sketches to the pro mini via standard IDE uploading. But if you wish to be able to burn bootloaders to your pro mini then you need a real 'programmer', which can be another arduino board running the arduinoISP sketch.

26  Using Arduino / Programming Questions / Re: digitalRead reads LOW even though it should be HIGH on: August 07, 2014, 12:09:35 pm
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pins on the arduino defaults to input

Possibly this is not literally true for the Due

 The Due has been out now for quite a while and I don't recall ever reading about having to set pins to input mode. However I don't have any direct experience with the Due. Can anyone nail this down as if true then the arduino reference for pinMode() should reflect that behavior on a Due?

27  Using Arduino / Project Guidance / Re: connection of dtmf decoder MT8870 and arduino uno on: August 06, 2014, 09:06:25 am
Hey,guys...
i have a dtmf decoder MT8870 and i'd like help on how
to connect it to the 2phones and arduino then
see it function...information plus schematics
will be well appreciated.ThankYou.

 Hooking a 8870 to an arduino is pretty simple, just 4 data input pins and one dataready input pin. However your desire to "connect it to the 2 phones" is not clear at all. What are the objectives of the project?

28  Using Arduino / General Electronics / Re: Gauging Interest: Printed Circuits on Paper on: August 06, 2014, 08:41:15 am
Maybe I missed where the original poster gave the conductivity of the ink?

The folks with the idea on Kickstarter say 0.2 Ohms/square.

Square what, acres?   smiley-wink
29  Using Arduino / Programming Questions / Re: Arduino Basic Program question on: August 06, 2014, 08:17:06 am
The AVR internal temperature sensor is a subject that never fails to pop up once a year or so. It's interesting but bottom line is that it is not a useful feature and I've yet to see a useful utilization of using it in a practical project.

 On the other hand access to the internal 1.1vdc voltage reference has been shown useful for being able to calculate the Vcc of a AVR at run time, useful in battery powered projects.

30  Using Arduino / General Electronics / Re: How to connect the arduino uno to the car alternator and also to use a 7.4V bat? on: August 06, 2014, 08:08:04 am
In a auto the alternator output and the battery are the same DC power bus. Just the voltage value changes when the motor is running and the alternator puts out a slightly higher voltage then just the battery alone when not running.

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