Discussion from Huaiwei Sun

[bwasmith]

I received an email from Professor Huaiwei Sun. The questions are copied below:

Firstly, we found you have pointed out the many sensors, but can you give some figures for jumper wires between the board pins and the RaspberryPi board?

Also, we found you have connected the Kipp and Zonen PAR Quantum Sensor, is it possible to connect other sensors from Kipp and Zonen? We found we could have a CM11 Pyranometer, but we didn’t know how to connect it to raspberry.

We also found you have pointed out the EC5 sensor, but have you connected it into raspberry? It may be very interesting to connect a sensor similar with EC5 and with soil temperature sensors additional.

[bwasmith]

Thank you for your message Professor. I am not sure what your knowledge of electronics, computing, and environmental sensing is, and so I will make some assumptions about what you do or do not know. I am by no means an expert myself. I hope this is of no offense.

Question 1

Firstly, we found you have pointed out the many sensors, but can you give some figures for jumper wires between the board pins and the RaspberryPi board?

This actually seems to be a big oversight of mine, a mistake. I don't think I ever had a document with all of the wirings. Only step by step instructions (which can be found in the Wiki). I had something hand-drawn, but that is long gone now.

This is a model I used to connect the RaspberryPi to my ADC(Analog to Digital Converter): Adafruit 4-Channel ADC Breakouts: Assembly and Wiring

This seems to be an updated figure: Adafruit 4-Channel ADC Breakouts: CircuitPython Microcontroller Wiring

From there, I connected the sensors to one of the four analog inputs. I believe my sensor had 3 wires: voltage input, ground, and sensor output(measured in millivolts, read by the ADC).

Reference: My info in I2C

Question 2

Also, we found you have connected the Kipp and Zonen PAR Quantum Sensor, is it possible to connect other sensors from Kipp and Zonen? We found we could have a CM11 Pyranometer, but we didn’t know how to connect it to raspberry.

I believe it is possible to connect other sensors to the Raspberry Pi. My system was independent of the sensors, but dependent on an ADC(Analog to Digital Converter).

I bought an ADC (Adafruit's ADS1115 which had an accuracy of ~8 microvolts, which was good enough for my Kipp and Zonen Sensor. I bought an ADC from a company founded by an MIT graduate, Adafruit. There is nothing special about the component itself, the main value is in the easy-to-use python libraries their community builds.

In my Connecting to ADC with Raspi Wiki page, I link to the old tutorial on Adafruit's website. This seems to be the new tutorial.

There is nothing specific about this ADC, nor their python packages, which is required. What is required is an ADC and an appropriate software package (I used Adafruit_ADS1x15, the new tutorial references a package called CircuitPython)

Question 3

We also found you have pointed out the EC5 sensor, but have you connected it into raspberry? It may be very interesting to connect a sensor similar with EC5 and with soil temperature sensors additional.

I was able to connect the EC5 sensor in the same way. If I remember correctly, it had a similar 3 wire system: voltage input, ground, sensor output (measured in millivolts).

I also remember having trouble with the quality of my measurements. I was not sure the age/condition of my sensors, and I also do not know much about soil moisture (I have an EE/CS background). I was getting inconsistent measurements. I would have liked to had extra time to read about soil moisture and buy new sensors so I could get the consistency I expected.

Going forward, My Recommendation

I only worked on this project for about 2 months after I graduated. If I were to continue the project, I would have finished getting the sensors, ADC, RTC (Real Time Clock), and Datalogger, and then tested out how well the system worked. From there, I would have worked with the Electrical Engineering department at UC Berkeley do develop a custom IC chip.

The do-it-yourself approach was designed for a classroom, instructive setting. This was supposed to help Environmental Science students get involved in environmental sensing.

If you want to produce a scalable finished product, a custom IC with all your component needs is probably the way to go. I would think if you had an Electrical Engineering department nearby, you should collaborate with them.

Please follow up with any clarifications or additional questions. I am happy to share what I know.

Best,
Brendan