HUMIDOMETER & BAROMETER

The weather station features a Honeywell HIH-3605-A relative humidity (RH) sensor. The sensor has worked well, so I’ve had no reason to change it. The small PCB holding the LM95071 also holds the RH sensor.

Barometric pressure used to be measured with a SenSym evaluation board that featured a dedicated ADC that drives a 3.5-digit digit LCD (another 7106). The pressure sensor was a Honeywell SCX15ANC, which had worked well for several years. I had originally planned to leave this section alone, but I changed my mind.

I used the pressure sensor from the evaluation board in the new weather station, but it’s interfaced to an Analog Devices AD7719 data acquisition system, which is a powerful new part with two ADC channels: one 24-bit and one 16-bit with a SPI. I haven’t fully tested it, so I didn’t include the code and schematics with this article. I do, however, have the AD7719 working with a microcontroller and a pressure transducer supplying raw barometric pressure data. It will be working in my upgraded weather station in the near future.