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Forum Index : Microcontroller and PC projects : PMM (Pico Mains Monitor)
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| lizby Guru  Joined: 17/05/2016 Location: United StatesPosts: 3319 |
Because I am very ignorant in these matters, can I ask if you can explain what effect the "picomite ADC not as good" would have for this application? PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on fruitoftheshed |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 10078 |
The RP2040 ADC has known linearity issues in the silicon. This means it is only good for about 8-bits of resolution |
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| lizby Guru Joined: 17/05/2016 Location: United StatesPosts: 3319 |
Thanks. I was aware of the linearity issue effectively limiting the RP2040 ADC to 8 bits of resolution. I was wondering how that would impact on this particular application. PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on fruitoftheshed |
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TassyJim Guru Joined: 07/08/2011 Location: AustraliaPosts: 6224 |
Due to the RMS calculations using a relatively high number of samples, that should be more than adequate for its intended use. Tracking a DC voltage looking for ripple etc would be more of an issue. Using it for spectral purity (waveform precision) will be dubious. I still haven't revisited my disturbance recorder project. For frequency, I was going to use a 1 sec pulse from a RTC (or GPS) and track the AC wave phase difference each second. That should give high resolution. Jim VK7JH MMedit |
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| Volhout Guru Joined: 05/03/2018 Location: NetherlandsPosts: 4867 |
Same thought here. Did not want a gps ao therefor calibrated my ds1307 to a gps. Need the rtc anyway for timestamping. Spectral purity through the fft, still have to calculate harmonic distortion by adding tje 13 lowest harmonics, and dividing by mains. PicomiteVGA PETSCII ROBOTS |
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| Volhout Guru Joined: 05/03/2018 Location: NetherlandsPosts: 4867 |
The mains monitor has been running for several months now, logging the trend data as BMP's (one per every 4 hours). Today I inspected the lot of BMP's and it was fun to spot the trends.... early morning (03:00...08:00) everyone is asleep, no solar panels working...  a day with large clouds, but sometimes 20 minutes full sun  end of the day, sun is setting  I am satisfied. With these small BMP files I can log years on an SD card 2Gbyte... Volhout P.S. is there an option to allow BMP upload to the forum ? PicomiteVGA PETSCII ROBOTS |
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Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 7540 |
I think they are usually too big. I know a lot of forums won't accept BMP because of that - and because they are binary dumps which could be anything. Best bet is probably to convert them to JPG or PNG. You could try putting them into a zip file. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| Volhout Guru Joined: 05/03/2018 Location: NetherlandsPosts: 4867 |
It is a simple task to convert them to jpg, so it is not a big issue. But on my screen the jpg looks a bit more flat, not as brilliant. Maybe due to the compression. Have seen rather large PNG's ... Anyway, I expect the answer to be in line with what you said... PicomiteVGA PETSCII ROBOTS |
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