Hi folks,
I'd like to set up a solar/battery-powered weather station.
The Teensy LC coupled with the air sensor and the 3.x/lc sd adaptor would AFAICT make a good starting point.
I'm not afraid of the software part of the endeavor, but this is my first embedded hardware project and I'm a bit puzzled as what would make an acceptable power supply. From this thread (some of the links are dead), I suppose that this charger coupled with this solar panel and possibly this battery would make a good combo. Could I replace the pannel with a pair of those in parallel? I have basic electricity notions, but little to no knowledge or intuition of circuits at this point, and I want to make sure that I don't fry something.
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As an extension to the above, I'd like to build a (ultra)sound-based anemometer, inspired by this project by Carl Morey (see attached pdf for details).
Simply put, the wind speed affects the speed of sound, and by measuring sound along two perpendicular axes you get both the wind speed and direction. One big advantage of this design is the lack of moving parts that can wear out.
Assuming the speaker and the microphone are about 30cm apart, it takes about 1 millisecond for sound to travel from one to the other. At low wind speeds, each Km/h of wind adds (or subtracts) about 1 microsecond.
The proper technique entails generating a ultrasonic sine wave and then determining how out of phase it is with the signal expected when there is no wind. This would require a speedy-ish ADC and DAC. (~160kHz seem reasonable for a 40kHz signal, unless I remember wrong and you need a higher resolution to extract the phase with the required precision). Can the Teensy LC handle such frequencies? From what I gather from the procssor specs the ADC limit is expressed in MHz so I'm covered, but I want to be sure.
Rather than the standard, tone-based technique, I'd also be tempted to generate and detect a single click (simpler to synthesize, but probably trickier to detect in noisy situations such as high wind or rain. The sine waves technique lends itself well to averaging, clicks less so if there is some jitter). For that to work I'd definitely need a MHz ADC conversion rate...
Anyways, rather than doing the DSP on the micro-controller, I'd be tempted to save the raw samples and do the processing offline so that I can play with the data in an interactive fashion, so I suppose I'll also have to worry about data transfer speed to the SD card...
I'd like to set up a solar/battery-powered weather station.
The Teensy LC coupled with the air sensor and the 3.x/lc sd adaptor would AFAICT make a good starting point.
I'm not afraid of the software part of the endeavor, but this is my first embedded hardware project and I'm a bit puzzled as what would make an acceptable power supply. From this thread (some of the links are dead), I suppose that this charger coupled with this solar panel and possibly this battery would make a good combo. Could I replace the pannel with a pair of those in parallel? I have basic electricity notions, but little to no knowledge or intuition of circuits at this point, and I want to make sure that I don't fry something.
----
As an extension to the above, I'd like to build a (ultra)sound-based anemometer, inspired by this project by Carl Morey (see attached pdf for details).
Simply put, the wind speed affects the speed of sound, and by measuring sound along two perpendicular axes you get both the wind speed and direction. One big advantage of this design is the lack of moving parts that can wear out.
Assuming the speaker and the microphone are about 30cm apart, it takes about 1 millisecond for sound to travel from one to the other. At low wind speeds, each Km/h of wind adds (or subtracts) about 1 microsecond.
The proper technique entails generating a ultrasonic sine wave and then determining how out of phase it is with the signal expected when there is no wind. This would require a speedy-ish ADC and DAC. (~160kHz seem reasonable for a 40kHz signal, unless I remember wrong and you need a higher resolution to extract the phase with the required precision). Can the Teensy LC handle such frequencies? From what I gather from the procssor specs the ADC limit is expressed in MHz so I'm covered, but I want to be sure.
Rather than the standard, tone-based technique, I'd also be tempted to generate and detect a single click (simpler to synthesize, but probably trickier to detect in noisy situations such as high wind or rain. The sine waves technique lends itself well to averaging, clicks less so if there is some jitter). For that to work I'd definitely need a MHz ADC conversion rate...
Anyways, rather than doing the DSP on the micro-controller, I'd be tempted to save the raw samples and do the processing offline so that I can play with the data in an interactive fashion, so I suppose I'll also have to worry about data transfer speed to the SD card...