19-02-2017, 23:47
The calibration that should be done (on the solar Radiation), is not because of the internal reference be 1.1V or not, but for reasons related to the physical construction of the sensor... as it depends on the way, each one builds its own device.
Think in the case of reading the UVM30A. The sensor have a maximum output voltage of 1.1V, if we chose to use the MCP1541, the maximum resolution would be seriously affected, compared to read it with a 1.1V voltage reference.
1.1 / 1024 = 1mV per step, opposed to 4.096 / 1024 = 3.4mV per step. Of course I could amplify the output of the UVM-30A, but why adding complexity?
Anyway, in both cases (Solar Radiation and UV) there isn't supposed that they are precision devices.
There is also another important reason to not use the MCP1541. For the FO wind vanes, we need 5V (4.9, or 5.1) for the ADC reference, 4.096V is too low.
Of course that any design options can be discussed, and I don't expect that everyone concords with them.
Think in the case of reading the UVM30A. The sensor have a maximum output voltage of 1.1V, if we chose to use the MCP1541, the maximum resolution would be seriously affected, compared to read it with a 1.1V voltage reference.
1.1 / 1024 = 1mV per step, opposed to 4.096 / 1024 = 3.4mV per step. Of course I could amplify the output of the UVM-30A, but why adding complexity?
Anyway, in both cases (Solar Radiation and UV) there isn't supposed that they are precision devices.
There is also another important reason to not use the MCP1541. For the FO wind vanes, we need 5V (4.9, or 5.1) for the ADC reference, 4.096V is too low.
Of course that any design options can be discussed, and I don't expect that everyone concords with them.