ADXL193 Accelerometer with Teensy 3.1

ADXL193 Accelerometer 5v analog sensor with Teensy 3.1

Hi

This may be a stupid question, but I just need to check I understand the 5v Tolerance on the 3.1

I have a ADXL193 that i need to use with a 3.1, it has a analog output that is related to the input voltage

on the datasheet https://www.sparkfun.com/datasheets/Sensors/Accelerometer/ADXL193.pdf
it states it needs 3.5 to 6 volts and I was planning on running it on 5v.

Am i understanding the 5v tolerance correctly?

If all digital pins are 5v tolerant, can they be used to analogread a 5v signal?

i.e. if I power the ADXL193 with 5v and connect the output to pin 23, and read the analog signal. will the teensy be ok?

I will post the details of the complete project on another thread

Thanks in advance

Lee

OK

I have found info on the analog 5v tolerance here

But it also states

But the full scale analog range is still only 3.3V.

Voltages from 3.3 to 5V read as 1023 (or whatever the maximum is, if you're changed the resolution).

Click to expand...

The ADXL will output 5V is the sensor sees a force of 250g but this will be seen as 3.3 or 1023?

I estimate I will not get over 100g so this may not be a problem

Would a voltage divider be the answer?

Any comments will be gratefully received

Lee

Others can probably answer this better than I can. I have not used this sensor. So far the only things I have used Analog inputs on the Teensy for, is on my breakout boards I do have a voltage divider to allow me to measure the battery voltages. And I have a DIY remote control where I have two joysticks with rotating knob as third DOF and 3 sliders.

But I think your answer depends on your needs. As I mentioned for measuring battery I use voltage divider as, for my usage may use a 3s lipo battery, so need to handle 14+ volts.
In your case. If the range of values you are interested in from your sensor fits in under the 3.3vs than you don't need to do anything. But if the valid range your are wanting to measure is getting near the 3.3v range or higher, you may want to use a simple voltage divider to give you the full range.

lowerstoford said:

I estimate I will not get over 100g so this may not be a problem

Click to expand...

According to the datasheet, there are 2 models. AD22282 is 18 mV/g. AD22283 is 8 mV/g.

If the DC offset is 2.5V and 3.3V is the maximum (800 mV range for positive g), you'll be able to measure a positive signal corresponding to 44g with AD22282, or 100g with AD22283.

Hi

Thanks for your replies

I now understand things much better.

Paul - Thanks for pointing out the differences on the datasheet, if I had read it correctly I would have been able to work this out.

If the DC offset is 2.5V and 3.3V is the maximum (800 mV range for positive g), you'll be able to measure a positive signal corresponding to 44g with AD22282, or 100g with AD22283.

Click to expand...

I have the AD22283 Chip so 100g. I estimate the Max g will be around 55-65g. So 100g is well within the scope.

I do have one more question the you may be able to answer.

Negative G - As far as I understand from the above information, the 3.1 will measure down to 250-g? as the 3.3v limit will only affect the positive +g.

This makes it even better as most of the g will be negative g

Once again thanks for your help

Lee