This was something completely unexpected since I have connected potentiometers to several of the ADC in pins and get the expected 0 to 5 V output (using the regulated 5 V out on the Arduino). The MSP-300 pressure transducer data sheet can be found at http://www.meas-spec.com/downloads/MSP300.pdf. The spec sheet calls for a 5 V input to the pressure transducer and it puts out an analog .5 to 4.5 V output along the range of its pressure rating (mine is 0 to 1000 psi). Before I plugged it into the Arduino, I fed it regulated 5 V from a separate power supply and read the output with a volt meter. It worked perfectly giving me the proper .5 to 4.5V output as displayed on the volt meter. But when I connected it to the Arduino with the Arduino regulated 5 V as the power source, the Arduino ground, and pin A15, the sensor worked for maybe 30 seconds and then died. It would no longer work with the external power and volt meter either. When the transducer is connected, it will periodically crash my software. But it is having no negative effect on the Arduino hardware. I just have to reset it and it starts up again. Also the potentiometer test still works on the A15 pin.
Now I connected it directly to the Arduino. Should I have included one or more resistors to limit the current? Could the Arduino have spiked the current output to the transducer? Any suggestions?
r u sure that A15 was conf'ed as input?
A15 as input has a very high impedance (if the ADC isnt sampling... )... 100MOhm or so...
But as output it can sink/source currents of 20mA, which would be outside of the typical operating conditions (load resistance: RL>5kOhm)...
did u check the color/number codes listed on page 3 of that datasheet?
the 5V USB and the onboard 5V linear regulator should impossibly be much above 5V...
the other chips wouldnt like it, 2... so in case of spikes there would be other damages...
the over current protection is quite liberal (a 500mA polyfuse, that possibly trips at 1A after a reasonable delay (at least those that i once bought need forever to react on currents that r 20% above their nominal current...)...)...
I did not set the A15 pin as an input. Would the potentiometer work on the pin if it were in output mode? I am asking because the pin is functioning with the potentiometer connected. I get 0 to 5 v displayed with a 5 v regulated power supply. I guess I assumed the default for the adc pin would be input. I added a pinmode input command to my software and compiled it successfully. I won't be able to test the fix until I get a replacement transducer.
This opens up another connection. Why would an ADC pin be set as output. Is there some application that would use this mode?
When the transducer is connected, it will periodically crash my software.
Alarm bells! A transducer can't directly crash software. What it can do however is to produce a short circuit across the 5V line, this takes out the power and the arduino resets when it comes back.
It sounds like you had a transducer failure unrelated to anything you did to it.
Did you ever get the MSP300 to work with an arduino. I am needing to make it work as well. I have good voltage reading but don't know how to turn the volts into psi and can't seem to find anything online. I have called the company to see also.
)... 100MOhm or so...