1. DIY PH and Data Logging Project
Peter Matsunaga
April 2017
Lots of slides.
Plan is to use them as an overview to support a demo of three projects
give the audience a look at what’s involved when you do it yourself

2. Project Start
2016 Dave set up pH control in the lab by regulating CO2 in seawater. goal: continuous ph measurement and logging .
He and Nicole were already doing this succesfully doing this
DIY ==

3. goal – make a mini photometer Dave also was very interested in a project by Bo Yang and others who built a DIY mini-photometer to measure pH, pH unit precision, one-time calibration, etc

4. My interests open source computing technology: Raspberry Pi and Arduino, environmental sensing Collaboration

5. The Characters
David, Nicole, Dr Smith, the probe === with this cast of characters we got started

6. Project Phases stand-alone glass-bulb pH sensor pH sensing and logging
Mini-photometer
Build skill and experience and work up to the mini-photometer project

8. Project #1 – Build stand alone PH Sensor and Temperature Sensor

9. pH problem and game plan …
I didn’t write this. Very good stuff directly from the trenches available on the Internet …

10. circuit to sense pH arduino to control, process, and read data
High gain low noise amplifier
Alarm level set
Temperature compensation
Measure very low voltages
0.059 V per ph unit ideal
0 v at ph 7
+ 0.17V ph 10
v ph 4
Analog Output to 5.0 v signal that
Corresponds to pH measured
Arduino provides the AD circuit and microprocessor
This is what you need to to solve the voltage translation problem …

11. P2 Documentation issue with some hardware sourced from Xina
P2 Documentation issue with some hardware sourced from Xina. Electronics is a universal language.

12. calibration : pH 4, ph 7, and pH 10 (3 point) voltage parameters
Arduino nano based pH Meter Software software design functional requirements
Read the voltages on the pH sensor and board using the 10bit A/D analog converter .
LCD display
3 button user interface
calibration : pH 4, ph 7, and pH 10 (3 point) voltage parameters
Store calibration parameters in static EPROM memory .
Retrieve calibration parameter from EPROM on device startup.
Calculate pH from voltage
averaging to dampen variability in raw pH readings
temperature probe

13. pH calculation
PhRead= analogRead(PH_ANALOG_PIN); H = params.phHiCal; L = params.phMidCal; HB = params.hiBuffer; LB = params.midBuffer; m = 1.0/ ( (H - L) / (HB -LB) ); b = HB - m * H; pH = m * PhRead + b;

15. Project 1 results .1 pH accuracy 10 bit AD Proof of concept
Stability concerns with el cheapo probe
Arduino alone does not solve data logging problem - not enough memory, data communications, lack of an operating system

16. Project #2 – A logging pH Sensor using embedded system technology

17. project 2 - concept of operation
Glass bulb sensors
Atlas Scientific EZO 6th gen embedded pH micro-processor based circuit
Computer to computer command based interface (i2c)
rPi 2 + wifi – linux operating system
easily handles data logging and data com
Wifi solves data comm problems – tcp/ip connect via cell phone / laptop
This was an exploration of advanced embedded system technology from Atlas Scientific

18. Project #2 – A logging pH Sensor
Demark slide

19. High level command interface to pH probe
Inter-Integrated Circuit
Eye squared C  
multi-master, multi-slave, packet switched, single-ended, serial computer bus 
SMBus Intel no licensing fees

20. Project 2 : Breadboard to prototype
So I built the thing and started testing.
C++
3 button control interface
3 point calibration
Etc etc

21. Project 2 Build

22. Anuenue installation

23. Raspberry SSH Few pictures to show functionality
The long term unsupervised probe was not a go. Requires maintnance.
Accuracy and consistency problems maybe related to the probe quality

24. results Wifi works noise problem Continuous immersion .05 (maybe) pH
Probe stability

25. Project #3 – pH Photometer

27. pH measurement with LED photometer
A portable LED photometer has been shown to provide seawater pH measurements (Jan 2014, Yang, Patsavas, Byrne,Ma) for pH 7.6 to 8.2 with precision of pH.
Built using commercial off the shelf components.
One time calibration.
Suitable for in-the-field and shipboard environments without need for recalibration.

29. RN = RB –
result of the calibration trial for Friday 18 Nov  We ran four sample blanks and reads through both narrow band (N) and broad band (B) photometers and got the results in the graph above.
The regression equation relates the broad band (mini photometer) to the narrow band photometer.

30. pH = equConstant + log10 (( RN – e1)/(1-RN*e23) )
Figure 1. RN to PH

31. Glossary Cots DIY Raspberry Pi Arduino AD Analog Digital
Voltage : E = IR volts mv uv
Current I = E/I ampere miliamp (ma)
Resistance R= E/I ohms
Power = EI = I2R watts
Capacitance
Inductance
I2C
One-wire
USB
Wifi
Tcp/ip
Ssh
Scp
Breadboard
Jumper wires
Integrated circuit
Pull up resistor
Current limiting resistor
Filter capacitor
Bypass capacitor
Impedance
Serial communication
Wall wart
Coax
Analog
Digital

32. End

33. The pH measurement problem
Literature (web search)
pH measurement – glass blub
pH measurement – photometry
Open source technology
Arduino
Raspberry Pi
Ph Probes
Electronics
data logging problem ( automation)
Data communications ( problem of closed sources )
programming
DIY – making the thing
1. Google foo

34. The calibration plan was to
obtain absorption readings for prepared sea water samples on  N at two wavelengths  578 and 434.   The LED’s used by B are close in wavelength :  574 (green LED) and 434 (blue LED)
compute RB and RN
compute the linear regression between RB and RN ordered pairs.

35. What is involved – from the outside in
Getting ph measurements and logging data
The user application interface and user manual
Productization
Packaging
user interface
software development (os , device driver, application software)
Computer/computing hardware
electronics
sensor

36. Who made it -terminology
COTS/GOTS
Commercial off the shelf
Government of the shelf
DIY –
Homebrew
In house
Internally developed

37. Decisions Instrument selection Precision - accuracy Ease of use
Calibration frequency
COTS or DIY

40. phmeasurement
The slide visual should show the sensor, the electronic amplifier package, the a/d converter, comment on the need for shielding and coax,
Goal – the students should understand the design considerations behind the instrument they are using whether it’s cots or diy

41. Topics The pH data logging problem DIY = (rpi,arduino) pH sensing
Temperature sensing
Sensing and accuracy
Data logging

42. The PH data logging problem
continuously monitor pH in a salt water tank
logging the data
A year ago, David and I had some conversations and we hatched the idea of trying out cheap DIY projects to measure pH and then see if we can solve the pH data logging problem

43. DIY = (rPi, arduino) DIY = (rPi, arduino)
A year ago, David and I had some conversations and we hatched the idea of trying out cheap DIY projects to measure pH and solve the pH data logging problem

44. What we’ll have to also talk about
Temperature Sensors
pH sensors
Raspberry Pi
Arduino
USB
Wifi
Linux Operating System

45. Why can you do it yourself NTBCW (not to be confused with) why do it yourself
Before DIY: required industrial tools and engineering degrees – electronics and computer programming ( within discipline)
During and post-DIY Technology
Inter disciplinary
Open Source (software)
Mass-produced (cheap) hardware – integrated circuits - microprocessors – sensors – shields and stamps
World-wide standardization on 5v and 3.3 V devices
World-wide standardization of data busses and data communications (I2C (I squared C or “I” two “C”), one wire, UART, USB, WIFI)

46. The BOM
List…. prices

47. Resources Electricity and electronics Computer programming language
Arduino (C++)
Raspberry Pi ( python )
Operating System
Data
Data communications
Data processing
Software design
Build

48. Device specific open-sourec library modules
Arduino
Raspberry Pi
We’re just going to list them here and not talk about them much.
Internet download of open

49. The Project
Objectives Design (approach) Cost effectiveness Resources

50. End of July Slides Feb 14 – request for
Celia asked me to ask you if you would come to a Lab Meeting some Weds at 11:30 (lunch) in March and give a 40 min introductory talk to our lab (grad students) about raspberries and pH measurement and what we hope to do.
It doesn't need to be polished or sophisticated or too hands on...we can do that later. We have a large screen TV that can hook to a laptop if PowerPoint or the internet is needed.

51. Raspberry Pie, Arduinos, DIY
2016 David invited me to come over and explore using raspberry Pi and open source hardware for pH measurements and logging

52. Agenda
Background
Goals

53. Goals
pH measurement and continuous logging

54. Glass ph sensors problem
Stability and calibration
Trial at Anuenue failed … the sensors could not take continuous immersion
Data logging is relatively easy but a pH sensor that can be under completely automatic cotnrol is so far

55. DIY PH Measurement
See “diagrams control systems.vsd” visio document “glass ph” tab 7/15/16

56. Background
Retired 2016
Cyber security analyst , DCO Architecture Chief- 4th Signal Center Defensive Cyber Operations Division, US Army
Netflow Development, performance management - Development Chief - Pacific Theater Network Operations / Security Center
Cyber / information system security professional, cyber intrusion analyst, CISSP/ GCIA
Security clearance: yes
IDS(intrusion detection system) / ASW (attack, sensing, warning ) sensor development, production, operations
Data analysist – data processing, medical encounter data processing, commercial application development, climate data rainfall, wind, solar energy, temperature
unix operating system, computer/info system, database system analysis and development
C, C++, perl, python, unix shell
Other
Computer Systems Operations Mgr (Unisys Corp)
commercial software development (accounting, fund development, imaging, PT/OT record)
Academic - Bio Geography, Climatology, micro-climatology (UH Geography Dept – BA,MA), rainfall, drought, computer science, operations research
Other- radio / electronics.
FCC Extra Class Radio Amateur License- KH6DK

57. The Start
2016 Dave – problem: measure and control pH in the lab by regulating CO2 in seawater.
My interest: environmental sensing using open source systems like the Raspberry Pi and Arduino
Dave also was very interested in a project by Bo Yang and others who built a DIY mini-photometer to measure pH, pH unit precision, one-time calibration, etc
He and Nicole were already doing this succesfully doing this
DIY ==