So I happen to have a TMP36 and decided to implement the temperature reading example. I connected it exactly as shown in the documentation, but I’m getting inaccurate readings. Whether I use a function, a variable or Serial.print I get values around 946. Using the method to convert this to voltage: …

So I finally collected enough data to visualise and I’m still seeing massive variation on readings. The graph below shows readings over nearly 24 hours and whilst the trend is correct it’s measuring 2-3 degrees above what I’d expect (this is probably easily explained) however its’s the odd variation…

Adding capacitance to the analog input is not the right answer because unless your also adding some significant resistor ahead of the cap to create a low pass filter in hardware… the cap is doing basically nothing except filtering some very high frequency (and low in power) noise that you wouldn’t s…

All valid points @mattande , but if it were ground bounce due to I x R drop from the CC3000 powering up… adding a cap to to the input (A0 to GND) should not make any difference. Actually it should make it worse due to the cap holding voltage well and pushing the A0 pin up with respect to VSSA due to…

I don't have one of these sensors but I have used the original versions some years ago. The Analog Devices datasheet says: Note the 0.1 μF bypass capacitor on the [power] input. This capacitor should be a ceramic type, have very short leads (surface-mount is preferable), and be located as close as…

Ok, adding a new theory here on these odd analog readings... Over in this thread: [image] Thermistors and the Spark Core Hardware Ok I have some good news for a change! Tonight I set off to characterize my temp probe from my …

[image] BDub: When it doesn't allow enough time, lowering the impedance effectively reduces the RC time constant that governs the speed at which a capacitor charges up. Are you sure the max input impedance spec isn't being violated? It's pretty low.

Not sure what you mean by that, but I'm pretty sure the max impedance currently is 600 ohms. [image] Odd analog readings [SOLVED] Troubleshooting Ok, looks like I’m collecting the Glory … lol After reviewing the Firmware sourc…

[image] BDub: Not sure what you mean by that, but I'm pretty sure the max impedance currently is 600 ohms. Assuming that that max allowed impedance is 600 ohms (from the link you gave), then the spec is probably being violated. In the adafruit thermistor tutorial, they're using a 10K resisto…

I found this PDF which seems to discuss the issue in detail: http://www.ti.com/lit/an/spna061/spna061.pdf At this point I’m really just trying to follow along and learn.

Agreed Raldus, but the “spec” is really whatever you set it to. I’ve already gave my recommendation as to what it “should” be set to… but so far no one has really agreed or disagreed. Just got put on the backlog. Some testing was done previously, but results were not positive. Not really sure ho…

Odd analog readings [SOLVED]

Troubleshooting

BDub April 9, 2014, 1:45am 57

Yep, check out this thread:

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Odd analog readings [SOLVED]

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