My sensor:
MPX5010DP
- Arduino UNO
I would like to know what is the resolution of pressure, for example, R = 1,7 Pa ...
That is an analog sensor, so the measurement resolution depends on the resolution of the analog to digital converter (ADC) that you choose, any averaging performed and the sensor noise.
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How many bits in the A/D 1023? That is your resolution plus or minus 1 count. Your sensor could be 0.0000000001 but the A/D is 5V/1023 or 0,0048 volts.
The correct divisor is 1024 for a 10 bit ADC. Oversampling and averaging can increase this resolution by a couple of powers of 2.
What happened to "0"? Starting with that you get 1023 counts or states or 00,0000,0000. - 11,1111,1111 or zero to 1023. Here is a calculator that will help. Decimal to Binary Converter 1024 needs an additional bit to represent in Binary. The first count is 0, 1, 2 not 1, 2, 3
Just quickly looking at the datasheet it looks like 10kPa is 5V (1023 on a 10-bit ADC).
So each "step" of the ADC represents 9.8Pa. 1.7Pa will read zero.
In addition to resolution there can also be accuracy & linearity errors (The 10-bit ADC is usually correct within 1 or 2 counts.
On the analog side there can be accuracy errors, linearity errors, noise, and drift.
1024 total states. The mathematics is absolutely clear on this point.
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...as is the manufacturer's datasheet.
Here is the full data sheet. The footnotes are just as important as the numbers.
With a ten bit A/D your theoretical resolution will be 0.009765625kPa, or 9.77Pa if you prefer. This assumes a supply voltage to the device of precisely 5.0 volts and a reference voltage of 4.70 for the A/D. Unless my brief perusal of the spec sheet missed something.
You measurement accuracy will be significant unless you compensate for all of the uncertainties as stated in the spec sheet, especially the zero offset which has a significant variability.
Edit: Actually the full scale error has a significant range too. If I was using this device I would have to do some calibrating either with software or hardware. Unless you are just looking for pressure change and absolute accuracy was not a problem.
Typical low output is 0.2volt, and typical high output is 4.7volt on a 5.0volt supply.
That's a span of 4% to 94%, or 90%, or 1024 * 0.9 = ~922 A/D values.
You could have a resolution (display steps) of 10 pascal with a bit of oversampling.
Leo..
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