STEP n°2: Measurement board¶
PART A Assembly of measurement board¶
Required 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 |
|
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 |
|
Resistor 1.5 Kohms +- 0.1% |
2 |
1.3 |
2.6 |
TE Connectivity |
H81K5BYA |
|
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 |
|
AQY211EH |
4 |
3.84 |
15.36 |
Panasonic Industrial Devices |
AQY211EH |
|
DIP Dual In Line Socket 2*2 |
4 |
0.449 |
1.796 |
Preci-dip |
110-83-304-41-001101 |
|
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 |
|
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 |
|
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 |
|
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¶
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 |
|
Installation of female header, 1 by10 pins, for ADS1115 |
2 |
|
Soldering of 4 dual-in-line- socket (2 by 2 pins) for optical relay, AQY211EH. |
3 |
|
Soldering of 1 dual-in-line- socket (2 by 9 pins) for INA282. |
4 |
|
Soldering of 1 dual-in-line- socket (2 by 4 pins) |
5 |
|
Soldering of 2 dual-in-line- socket (2 by 4 pins) |
6 |
|
Traco Power Supply 12V to 5V, TDH15 - 1211N |
7 |
|
Four screw terminals for 12V inpout et 5V outpout |
8 |
|
Traco power Supply 12V to 24V, TRN-1215 |
9 |
|
Two screw terminals electrodes M and N |
10 |
|
Four screw terminals, for 12V power supply and for electrodes A and B |
11 |
|
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 |
|
2 ohms shunt resistor pre-adjustment |
13 |
|
Soldering 2 ohms shunt resistor |
14 |
|
1 Mohms resistors |
15 |
|
Soldering tow 1 Kohms resistors |
16 |
|
Soldering tow 1.5Kohms resistors |
17 |
|
Soldering tow 1.5Kohms resistors |
18 |
|
Female header 2 by 20 pins for Raspberry Pi connection |
19 |
|
View of the female header 2 by 20 pins installation for Raspberry Pi connection |
20 |
|
Fixing MCP23008 component |
21 |
|
Mounting optical relay, AQY211EH |
22 |
|
Mounting LM158 operational amplificator |
23 |
|
Mounting ADS115 board |
24 |
|
Fixing the INA282 |
PART B Start-up of the measurement board¶
Required 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 |
|
Shutdown the raspberry Pi and unplug the power supply |
2 |
|
Mounting the bottom spacers on the Raspberry Pi (male/female, 11mm, M3) |
3 |
|
Mounting the upper spacers on the Raspberry Pi (female/female, 11mm, M3) |
4 |
|
Mounting the Ohmpi’s measurement board on the Raspberry Pi |
5 |
|
Mounting the Ohmpi’s measurement board on the Raspberry Pi |
6 |
|
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 |
|
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
Schematic of equivalent electronic circuit test
3 |
|
Prepare the equivalent electronic circuit test |
4 |
|
Prepare the battery connections and the terminals. |
5 |
|
Soldering cables and terminals |
6 |
|
Install the red cables on the +12V terminal and black cable on the ground terminal. |
7 |
|
Connect the equivalent electronic circuit test |
7 |
|
Run Tonny Interpreter |
7 |
|
Run Ohmpi_4elec.py, if everything works you should get the following result (220 ohm) |