Dear all,
I started a new project to measure tides variation with Arduino (as a beginner in Arduino). And I find a very robust sensor: the SS100 series piezoresistive pressure transducer. It is 10Bar Absolute pressure sensor. the datasheet is attached. I am not sure about conections and code. Could some one give me an example of code and wiring in the Arduino?
Thanks!
5689d3f9baebe(1).pdf (588 KB)
This is not a good sensor for an Arduino beginner. It outputs an analog value but the polarity may change depending on the pressure applied. That sensor needs a lot of additional circuitry to be safely attached to an Arduino.
Please provide more information about how you try to measure the tides variation (a drawing of the planned setup may help), there may be people in the forum that can suggest a better matching sensor.
Moab:
I started a new project to measure tides variation...It is 10Bar Absolute pressure sensor.
Are you expecting a 90 meter tidal variation?
If you want some resolution, you must match the sensor to the tidal variation in your area.
Leo..
Looking at that data sheet I can't even figure out how to connect it... It's sparse on details. There's a 100 mV output (which would require amplification) but a +/- 20mV variation on this, so it appears the sensor needs calibration.
Then indeed a smaller range sensor may work better. In my locality the tidal difference is 2-3 meters (though last year a storm added almost 3 meters to this), so a 10 meter difference (10 bar) would do. Most parts of the world have <10 meters total difference including storm surges.
For the linked sensor, maybe use a 500x amplification to go from 100 mV to a 50V full scale - if your amplifier gets only 5V input you're safe, as it basically means you're using the lower 10% of the range.
wvmarle:
...so a 10 meter difference (10 bar) would do.
10 bar absolute is a head of ~90 meters of (sea)water.
Leo..
Ah yes miscalculated a 0.
But then, a 0 by itself is nothing. So actually I added nothing, yet it changes everything. Isn't it surprising how important nothingness can be?
A 1 bar gauge (not absolute) sensor with buildin instrumentation amp and buildin temp compensation could be better/easier. Must add a barometric sensor sensor too for air pressure compensation.
Several other ways too to measure water hight (bubbler, ultrasound, float/switch).
Leo..
A major complication is that it's the sea level OP is trying to measure. Waves are a major disturbance, somehow that has to be taken into account and corrected for.
Pressure or ultrasound are probably the best methods, with some serious correction for waves.
Makes me wonder how tide gauges are normally constructed.
Tidal variation (without storm surges) is well known, and comes free with a charting program (openCPN is free).
Just had a look at that, and I see that most tidal icons are positioned in harbours and bays (calm water).
Leo..
The actual tides are often >20 cm off the predicted levels, and that's without storms, but effects of normal winds, high/low pressure areas, water temperature variations, and probably a few other variables.
Such a difference is not very big, but for the geotours that I host it makes a difference between being able to enter a sea arch or not, or whether you can see a nice long tombolo or not. That's also why I even know about this stuff 
That most such gauges are in harbours and bays also has to do with the need of knowing the actual tide in those places, and general ease of accessibility. Hong Kong's Waglan Island and Beaufort Island have tide gauges and weather stations on them, both places are known for their rough waters and high winds.
wvmarle:
That's also why I even know about this stuff
Hidden talents aye
Used to sail the big blue water (lived several years with my family on a sailboat in the Pacific).
The depth sounder was my tidal gauge.
Leo..