On 08/08/2019 14:50, T i m wrote:
Peeps,

I would like to read the output of a strain gauge (measuring weight
(0-5kg) in this instance) from a PC as part of a general experiment
but not sure what bit does (and maybe limits), what.

So, strain gauge (or gauges) connects to a SG amp and that turns the
output into volts?

Then you could read said volts with say an Arduino and then have a USB
interface to PC, effectively streaming the output of the strain gauge
in ASCII (numbers) to the PC (and the rest is software etc) .

Yup, or use a Arduino with Wifi and you can make it available on TCP/IP
or even a simple embedded web sever.

However, I understand the Arduino's only have a 10(12 with a tweak)
bit ADC and so with 10 bits I'm only going to get 1024 output values?

Sounds like it.

However, there are other options...

You could use an external ADC with more resolution and talk to it on the
I2C bus - trivial to do on an Arduino.

https://www.adafruit.com/product/1083

Or I suppose you could use scaling and DC offsets (with some clipping to
protect the ADC) to feed a couple of ADC channels so you can read coarse
and fine readings and combine them in software.

eg, If that was a 1kg 'scale' then I could read around 1g increments
but if it was a 5kg scale then ~5g would be the smallest increment
(that may be fine but I am just testing my understanding here).

Or is the output of the little eBay strain gauge amps already serial
so if it was a 24 bit device (16777216)

That gets me a brake hose!

it would be resolving down to
~1/3000 of a g (mathematically at least) and so would just use the
Arduino to turn it into ASCII over a USB interface (no ADC needed)?

I know you can buy commercial strain gauge to ASCII over USB devices
but they aren't exactly cheap (~£250+).



--
Cheers,

John.

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