I did a bunch of testing today with my TMP36 temperature sensor to try and get to the bottom of why the readings are so wacky. This is a continuation of the Odd analog readings thread , but I felt you might want to find this information without reading 55 replies :wink: How to get accurate analog r…

Hi @satishgn I have a work-around that removes the max and min from the average, but this is just band-aiding (plastering) over the problem. It would be best to find out why there is an extra zero in the average–the answer is almost certainly a bug! Here’s my code–I could not get the github gods t…

@bko , Provided a fix for the extra zero in the converted data by: 1)Changing the DMA mode from “circular” to "normal" 2)Enabling ADC2 external trigger conversion for each analogRead 3)Reset the buffer and DMA counter before starting the ADC-DMA command Commt : https://github.com/spark/core-firmw…

Hi @satishgn This worked great on my test case and I like that you merged the loops to cut down the overhead. Nice job and thanks!

Thanks @bkp for verifying the results. For those interested in STM32’s Advanced ADC Modes, here is an application note from ST: STM32%27s+ADC+modes+and+their+applications.pdf 240.55 KB

When do you think this will get pushed out to allow us to build using the WebIDE and not experience the cross-talking issues between analog channels? I know I can use the USB approach, but I’m curious what the timeline is for seeing it in the over-the-air version.

@mbeasley Usually it will be announced in the forum as well. [image] Is there an alternative to "pressing the Mode Button" for Smart Config &... Hardware We did push new firmware to the build servers last night, but that proba…

@satishgn I haven’t read the whole thing yet, but this jumped out at me: The dual slow interleaved ADC mode is intended for the conversion of one channel. ADC1 and ADC2 convert the selected channel alternately with a period of 14 ADC clock cycles. The channel is thus converted every 14 clock cycl…

@BDub , good find. This was a big surprise to me as how the sampling time was bumped from the original 1.5 to the current 41.5. Think it happened during the community provided merge. I will update and test the code again to see how the change affects the whole process. Thanks

Yes it was from a direct result of this thread :slight_smile: See first post. I’m guessing you’ll want to stay to the high end 13.5. Having it set to 41.5 probably yields 13.5 max anyway so I don’t know if there will be much change in how it responds. Comparing to the old way of 41.5 single chan…

@BDub correct after trying out with 1.5, 7.5 & 13.5, readings are pretty much similar to 41.5 sampling time. But I haven’t tested it comprehensively as you did in your first post. Would you like to repeat the test and see how the use of Dual ADC compares with the single ADC in terms of input impede…

Odd analog readings (part 2)

Troubleshooting

kennethlimcp March 5, 2014, 12:32pm 38

@mbeasley Usually it will be announced in the forum as well.

Two variables return the same value (periodically)

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Odd analog readings (part 2)

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