I've never seen an automotive pressure sensor that was absolute. They are all Gauge pressure. I very much doubt you have absolute transducers, most likely low accuracy gauge type
These are not what I would call high end transducers. This site claims 2% error without any explanation of how the error (if real) is calculated. Also you didn't mention how much off the 102 count your transducer.
Easy test. Connect the transducer to your arduino and leave it sit. Monitor the readings every couple of hours for maybe a day and see how stable it is. After that, repeat the test but warm or cool the transducer, see how much it changes with temperature. See if the short term change is stable enough for you to even consider.
For any pressure transducer the most unstable parameter is the zero offset. Even in the most costly sensors this is the most difficult characteristic to keep stable. And the arduino is not what I would call a precision device.
So I think you should look at your goals from the application side. A good rule of thumb is one should use a transducer at about 2/3 of the max range. This means you will require transducers with different ranges.
You mentioned your expected pressure values but you didn't mention what you need to measure to accomplish your goals. Is it there or not there? Or do you need values?
I realize you must stay with the Arduino for readings. However if you expect any precision I strongly suggest you get one with this chip on it MCP3421
The delta sigma conversion is the key here. They are inherently low noise and rejecting most periodic noise. You will need three of these, one for each transducer and one for the 5V transducer supply. I thought there was another type of delta sigma converter with multiple input channels but I couldn't find it in a quick eBay search.
Hi John Robert,
Quick follow up on the mcp342X.
The X in the PN indicates the number of channels.
The 342x is an 18 bit version, lower versions exist, all the way down to the 10 bit 30xx.
Do I understandyyou correctly:
Install an MCP really close to the sensor.
Supply both with 5V, ground one input and connect the pressure transducer's output to the remaining input of the MCP...
This would certainly reduce noise due to EMI, ground loops, ionization currents in the water etc...
My question is around the I2C... The sensors are as far as 6m (20') from the Arduino. Will this create and issues. The forum seems split on the issue. I newly have 22awg/4 shielded sensor wire installed.