2017-08-18 at 10:39 AM #2336
I have some sensors that provide 0-5 volt signals. Due to the instrument’s sensitivity, I need to use the auxiliary adc. However, I cannot find any documentation about how the board is laid out to know if the ADC is capable of reading 5 volts. I saw the .png schematic on the hardware section, but that isn’t as helpful as I would like since it doesn’t show board traces or wiring between sections.
The schematic also has two different adc part numbers. Is it the ADS1015 or the ADS1115? The board label says 12 bit, but below that, the label says ADS1115, which is the 16 bit version.
Is there more documentation somewhere else that I’m just not seeing?
2017-08-21 at 8:56 AM #2340
We haven’t shared the board layout yet, but all of the necessary information is in the schematic. The aux ADC on the Mayfly is the ADS1115. Its Vcc is tied to the 3.3v supply of the board, so it’s not possible for it to sample anything greater than that. You can use the jumpers near the Grove connectors on the board to provide a 5v excitation for external sensors, but the sensor must not return a signal greater than 3.3v. For all of our deployments, we use sensors that have 5v excitation but provide a 0-2.5v return. If your sensor returns 5v, you can simply use a resistor divider to change the voltage to something within the safe range of the ADS1115.
2019-02-19 at 12:24 PM #12806
@brandon9, great news! The Mafly logger is now fully open source hardware!
The EAGLE files are now available for the Mayfly v0.5b!
We also packaged things up nicely, including additional documentation, into official releases, https://github.com/EnviroDIY/EnviroDIY_Mayfly_Logger/releases, which we’ve made fully citable: https://doi.org/10.5281/zenodo.2572006
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