STEP n°2: Measurement board

PART A Assembly of measurement board

Required components

alternate text
List of components

Component

Number

Cost per unit €

Total cost €

Manufacturer

Manufacturer s reference

Web reference

Raspberry Pi 4 Model B

1

58.75

58.75

Raspberry

Raspberry Pi 4 Model B

https://www.mouser.fr/ProductDetail/Seeed-Studio/102110421?qs=7MVldsJ5UaxeN3LYyh3sqw%3D%3D

LM158N AMP-o

4

14.5

58

Texas Instruments

LM358AN/NOPB

https://www.mouser.fr/ProductDetail/Texas-Instruments/LM158J?qs=X1J7HmVL2ZH8vpEfMl8%2FFQ%3D%3D

Printed circuit board

1

12

12

Asler

ADS1115

2

11.9

23.8

Adafruit

1085

https://www.mouser.fr/ProductDetail/Adafruit/1085?qs=%2Fha2pyFaduhE%2FOGzuTWIQ9Iz5VjaqFOYugqAlGxpEcKiGrQvF4hn%252Bg%3D%3D

Capacitor 100nF 50Vdc 10% Ceramic

4

0.2

0.8

KEMET

C320C104K1

https://www.mouser.fr/ProductDetail/KEMET/C320C104K1R5TA7303?qs=c4UyoTs%2FLq1th4mcyOeTmA%3D%3D

Resistor 1 Kohm 0.5W +- 0.1%

2

1.3

2.6

TE Connectivity

H81K0BYA

https://www.mouser.fr/ProductDetail/TE-Connectivity-Holsworthy/H81K0BYA?qs=%2Fha2pyFaduhUylh7Az%2FmjFH2XjOUms6wZtUX4sOM%252BII%3D

Resistor 1.5 Kohms +- 0.1%

2

1.3

2.6

TE Connectivity

H81K5BYA

https://www.mouser.fr/ProductDetail/TE-Connectivity-Holsworthy/H81K5BYA?qs=%2Fha2pyFadugy9tWham3rU9HmIJOhyWhBIN95kNm%252BX%2FM%3D

Resistor 1.5 Kohms +- 5%

2

1.3

2.6

Vishay

CCF071K50GKE36

https://www.mouser.fr/ProductDetail/Vishay-Dale/CCF071K50GKE36?qs=QKEOZdL6EQpA6LZRLQFVOw%3D%3D

Resistor 10 Mohms +-5%

2

0.762

1.524

VISHAY

CMF651M0000FKEK143

https://www.mouser.fr/ProductDetail/Vishay-Dale/CMF651M0000FKEK143?qs=CiayqK2gdcKzIA2LEVaLkg%3D%3D

2 ohm shunt resistor+- 1%

1

2.42

2.42

Ohmite

41F2R0E

https://www.mouser.fr/ProductDetail/Ohmite/41F2R0E?qs=IM6ToxQzGOAuEDprb19mHA%3D%3D

Dual screw terminal (5.08-mm pitch)

5

0.648

3.24

CUI Devices

TB009-508-02BE

https://www.mouser.fr/ProductDetail/CUI-Devices/TB009-508-02BE?qs=vLWxofP3U2wCFk5uCkWTkA%3D%3D

DC/DC converter 12 to 24V

2

15.58

31.16

TracoPower

TRN 3-1215

https://www.mouser.fr/ProductDetail/TRACO-Power/TRN-3-1215?qs=YCa%2FAAYMW02gqUicGQj0tA%3D%3D

DIP Dual In Line Socket 2*4

3

0.72

2.16

Mill-Max

110-43-308-41-001000

https://www.mouser.fr/ProductDetail/Mill-Max/110-43-308-41-001000?qs=IGgAdOvCTsTu%2FqaUr8NArg%3D%3D&mgh=1&vip=1&gclid=EAIaIQobChMIn_TAxbCx8wIVQ5nVCh2QaQFpEAYYCCABEgJk1_D_BwE

AQY211EH

4

3.84

15.36

Panasonic Industrial Devices

AQY211EH

https://www.mouser.fr/ProductDetail/Panasonic-Industrial-Devices/AQY211EH?qs=wKtUvITRialGIU8hcM7DvQ%3D%3D

DIP Dual In Line Socket 2*2

4

0.449

1.796

Preci-dip

110-83-304-41-001101

https://www.mouser.fr/ProductDetail/Preci-dip/110-83-304-41-001101?qs=%2Fha2pyFadujQKqx4wAuiG%2FMGNdxMCNv%2F33Nj0gBxRocuLUcYnpyONg%3D%3D

SSQ-103-03-G-D

1

2.06

2.06

Samtec

SSQ-103-03-G-D

https://www.mouser.fr/ProductDetail/Samtec/SSQ-103-03-G-D?qs=rU5fayqh%252BE2Z%252BZTchcPoHQ%3D%3D

MCP23008

1

1.72

1.72

Adafruit

593

https://www.mouser.fr/ProductDetail/Adafruit/593?qs=sGAEpiMZZMsKEdP9slC0YYV4kPdpMD1Hts4SLctIVmw%3D

Header sets 1x10

2

2.12

4.24

Samtec

SSW-110-02-G-S

https://www.mouser.fr/ProductDetail/Samtec/SSW-110-02-G-S?qs=rU5fayqh%252BE0w1ORXZiBQpw%3D%3D

SMT Breakout PCB for SOIC-8

1

2.5

2.5

Adafruit

1212

https://www.mouser.fr/ProductDetail/Adafruit/1212?qs=GURawfaeGuCAqqfvnVtyeg%3D%3D&mgh=1&vip=1&gclid=EAIaIQobChMIt8zJzr6x8wIVGdnVCh2vBwVsEAQYAyABEgJqG_D_BwE

INA282AID

1

4.11

4.11

Texas Instruments

INA282AID

https://www.mouser.fr/ProductDetail/Texas-Instruments/INA282AID?qs=Ze4%2FuFuz19ILFayZXOCfrA%3D%3D

THD 15-1211N

1

39.72

39.72

TracoPower

THD 15-1211N

https://www.mouser.fr/ProductDetail/TRACO-Power/THD-15-1211N?qs=%2Fha2pyFadugpyEG4IDvm%2FMSR%252B7aN%2F0T3rUIs9PCAqJlT4%252BnRpUOOeQ%3D%3D

DIP Dual In Line Socket 2*20

1

8.53

8.53

Samtec

SSQ-120-23-G-D

https://www.mouser.fr/ProductDetail/Samtec/SSQ-120-23-G-D?qs=rU5fayqh%252BE1BMVd%252BDZONqg%3D%3D

Pin strip no ejector

1

0.35

0.35

BLK electronic

10120550

https://www.conrad.com/p/bkl-electronic-10120550-pin-strip-no-ejector-contact-spacing-254-mm-total-number-of-pins-6-no-of-rows-2-1-pcs-741435?searchTerm=741435&searchType=suggest&searchSuggest=product

Male Female spacer 2.5M HEXAGONALE

4

0.87

3.48

HARWIN

R25-3002002

https://www.mouser.fr/ProductDetail/Harwin/R25-3002002?qs=W0yvOO0ixfENUv0hsdC4%2FQ%3D%3D

Description

alternate text

Figure shows the general schematics for the electronic measurement board developed. We have developed a complete “plug and play” measurement board. To measure electrical resistivity with Raspberry Pi. two ADS1115 were used,one for the voltage measurement one for the current measurement, as proposed by Florsch [7]. The ADS1115 is a 16-bit ADC (Analog-to-Digital Converter), with an adaptable gain. The advantage of ADS1115 is that the input signal value could lie between - to + 6.114 V. For the current measurement we have directly integrated the INA282 component, which allows to realize precise current measurement around a shunt resistor. The assembly are described in the following steps:

1

../_images/01_mes_board.jpg

Installation of female header, 1 by10 pins, for ADS1115

2

../_images/02_mes_board.jpg

Soldering of 4 dual-in-line- socket (2 by 2 pins) for optical relay, AQY211EH.

3

../_images/03_mes_board.jpg

Soldering of 1 dual-in-line- socket (2 by 9 pins) for INA282.

4

../_images/04_mes_board.jpg

Soldering of 1 dual-in-line- socket (2 by 4 pins)

5

../_images/05_mes_board.jpg

Soldering of 2 dual-in-line- socket (2 by 4 pins)

6

../_images/06_mes_board.jpg

Traco Power Supply 12V to 5V, TDH15 - 1211N

7

../_images/07_mes_board.jpg

Four screw terminals for 12V inpout et 5V outpout

8

../_images/08_mes_board.jpg

Traco power Supply 12V to 24V, TRN-1215

9

../_images/09_mes_board.jpg

Two screw terminals electrodes M and N

10

../_images/10_mes_board.jpg

Four screw terminals, for 12V power supply and for electrodes A and B

11

../_images/11_mes_board.jpg

Soldering three capacitors (100nF)

Warning

In this version, We used a shunt resistor of 2 ohms, which limits the current measurement to 48 mA. If the current is higher than this value, you just have to decrease the value of the shunt resistor.Change the shunt value in the code.

12

../_images/12_mes_board.jpg

2 ohms shunt resistor pre-adjustment

13

../_images/13_mes_board.jpg

Soldering 2 ohms shunt resistor

14

../_images/14_mes_board.jpg

1 Mohms resistors

15

../_images/15_mes_board.jpg

Soldering tow 1 Kohms resistors

16

../_images/16_mes_board.jpg

Soldering tow 1.5Kohms resistors

17

../_images/17_mes_board.jpg

Soldering tow 1.5Kohms resistors

18

../_images/18_mes_board.jpg

Female header 2 by 20 pins for Raspberry Pi connection

19

../_images/19_mes_board.jpg

View of the female header 2 by 20 pins installation for Raspberry Pi connection

20

../_images/20_mes_board.jpg

Fixing MCP23008 component

21

../_images/21_mes_board.jpg

Mounting optical relay, AQY211EH

22

../_images/22_mes_board.jpg

Mounting LM158 operational amplificator

23

../_images/23_mes_board.jpg

Mounting ADS115 board

24

../_images/24_mes_board.jpg

Fixing the INA282

PART B Start-up of the measurement board

Required components

List of components

Component

Number

Cost per unit €

Total cost €

Manufacturer

Manufacturer s reference

Web reference

Spacer 3x11 mm

8

0.39

3.12

Wurth Elektronik

971110321

https://www.mouser.fr/ProductDetail/Seeed-Studio/102110421?qs=7MVldsJ5UaxeN3LYyh3sqw%3D%3D

Screw

4

0.305

1.22

APM HEXSEAL

RM3X8MM-2701

https://www.mouser.fr/ProductDetail/APM-HEXSEAL/RM3X8MM-2701?qs=JJSE%2F12mKnS3VxSDrYXUHw%3D%3D

1

../_images/001.jpg

Shutdown the raspberry Pi and unplug the power supply

2

../_images/001.jpg

Mounting the bottom spacers on the Raspberry Pi (male/female, 11mm, M3)

3

../_images/002.jpg

Mounting the upper spacers on the Raspberry Pi (female/female, 11mm, M3)

4

../_images/003.jpg

Mounting the Ohmpi’s measurement board on the Raspberry Pi

5

../_images/004.jpg

Mounting the Ohmpi’s measurement board on the Raspberry Pi

6

../_images/005.jpg

Plug the power supply into a socket and connect it to your Raspberry Pi’s power port.

PART C Check the measurement board

Run the terminal, and write

i2cdetect -y 1

1

../_images/i2cdetect.png

If everything is working, three I2C addresses should appear on the screen.

Setting up an equivalent electronic circuit, for this you will need:
  • 4 1kohm resistor (R2)

  • 1 220 ohm resistor (R1)

  • 1 small padboard

  • Spool of solder

2

../_images/ref_circuit.png

Schematic of equivalent electronic circuit test

3

../_images/20210905_122820.jpg

Prepare the equivalent electronic circuit test

4

../_images/20210905_123034.jpg

Prepare the battery connections and the terminals.

5

../_images/20210905_132856.jpg

Soldering cables and terminals

6

../_images/Inked20211206_150522_LI.jpg

Install the red cables on the +12V terminal and black cable on the ground terminal.

7

../_images/Inked20211206_150522_LI2.jpg

Connect the equivalent electronic circuit test

7

../_images/thonny_first_interface2.jpg

Run Tonny Interpreter

7

../_images/20211206_144334.jpg

Run Ohmpi_4elec.py, if everything works you should get the following result (220 ohm)