Atmega and UGN3503 Hall Effect sensor

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#1
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Hi,
i started to work with this:

http://profmason.com/wp-content/...

but i don't exactly understand what to do as i am new to ADCs.

i simply attached the sensor's output to one of the ADC pins of my mega16 with the internal 2.56V ref. and displayed the ADCW (ADC output value) on my LCD. it reads about 994 normally.

i don't understand from the datasheet what is the zero and span of the sensor.

i am sure i must do some calibration and some other works to make use of this sensor.

please help me what should i do .
(i am not sure for what usage i am going to use this sensor, just wanted to get introduced to the sensor. ) :)

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Quote:
The output null voltage (B = 0 G) is nominally one-half the supply
voltage.

As this is a 5V device, I assume that is your supply V. So ~2.5V (994 counts) certainly makes sense. Remember to look in the datasheet for what you can expect the >>real<< value of the internal reference to be.

Quote:
A south magnetic pole, presented to the branded face of the Halleffect
sensor will drive the output higher than the null voltage level. A north
magnetic pole will drive the output below the null level.

That sounds straightforward to me. I don't know what the units would be. Aaah--there it is:

Sensitivity ΔVOUT B = 0 G to ±900 G 0.75 1.30 1.75 mV/G

What are you trying to measure? Why would you select this particular sensor if you have no idea how to interface to it?

Lee

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

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Thanks.

Quote:
What are you trying to measure? Why would you select this particular sensor if you have no idea how to interface to it?

i am trying to build a speedometer for my wheel.
i recently found that the Hall Effect Switches are better for this purpose.

and as i said, i mainly wanted to have an experience with a hall effect sensor.

BTW, now the problem is how to set the ADC to be scaled to be able to show the 2.5 V ± 900 * ~1.3mV .

P.S: how can i know how much is the response time of the sensor to a particular magnet ?

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To measure a full 5v signal you need to use AVCC as the reference. To figure out how much your magnet affects the output you simply need to experiment (unless you know the field strength of the magnet.

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If you're building a speedometer, just use a standard hall effect device with 0 and VCC output. ie. open collector output. Pullup resistor required.
You also won't need to use the ADC, just a digital I/O pin.

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ADI8421 wrote:
If you're building a speedometer, just use a standard hall effect device with 0 and VCC output. ie. open collector output. Pullup resistor required.
You also won't need to use the ADC, just a digital I/O pin.

I think you mean a Hall Effect Switch .

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OK ... so you're all sorted then ?

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Quote:

OK ... so you're all sorted then ?

yes, i will get one Hall switch and try to work with that.

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what is that symbol which is like a capacitor in this schema ? which has a label of 0.1/50V nearby. ? what does 0.1/50V mean ?
http://screencast.com/t/cx210Jg4D

i think it is a capacitor used for noise cancellation. if i am right, which capacity should i use for this purpose ?

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Though the units aren't shown it is likely a 0.1uF 50volt rated cap.