ATmega48A and TPF-2A load cell ???

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Hi there,

 

I am wondering of how to read (via the AVR ADC input) this device:

 

http://transdutec.com/catalogo/T...

 

I am using ATmega48A micro.

 

Any help please ?

 

 

 

Michael.

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Micro with differential ADC would be much better. Now you have to measure both outputs and do the difference in program.

Computers don't make errors - What they do they do on purpose.

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You need a load cell amp.
https://www.sparkfun.com/products/13230

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First, look at the specs.

 

The sensitivity is 2mV/V. That is the full-scale voltage output per volt of excitation. Lets suppose that you drive the load cell with 5V. Then the full scale output is 5V * 2mV/V = 10mV. That is the full scale output. FULL SCALE. 

 

Second, that output is differential. You really need to measure the DIFFERENCE between the two output terminals.

 

micros with differential input ADC would be MUCH better in this application, but the resolution would still be very poor. All of the Mega/Tiny ADCs, as far as I can recall, are 10 bits. Suppose that your reference is 1.024V. Then 1 bit will be 1mV. You would ONLY have 10 counts between 0 and full scale. That would be a very poor scale! Differential with gain would improve this by a very large amount.

 

In at least one respect, the specifications are a bit odd. It talks about the "number of divisions". A load cell is NOT quantized and should have no resolution limit beyond the resolution of the measuring system. It is common to use an instrumentation amplifier (IA) to amplify the signal to a level that an A/D can handle AND to change it from differential to single-ended. 

 

Jim

 

 

Until Black Lives Matter, we do not have "All Lives Matter"!

 

 

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KIIV_cz wrote:

Micro with differential ADC would be much better. Now you have to measure both outputs and do the difference in program.

 

Micro with differential >>and amplification<< would be much better.

 

And might work OK for a non-precision application.  For more precise and accurate load cell work, there are now devices specifically for that purpose:  instrumentation amp+appropriate ADC+soft-tune+...

 

https://www.avrfreaks.net/comment...

...and follow link

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