hx711 zero factor notes

HX711 zero factor

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I have three load cells (YZC-1B). This load cell’s capacity is 50 kg. I guess I use Bogde’s HX711 library.

In monitor, zero factors for first two load cell, 8,000,000 but in last load cell zero factors is 40,000. When I swap the green and white wire (swapped A- and A+) zero factor is again 8,000,000 value. But last zero factors (8 million) has been negative value and my load results are got a negative value.

When I look from the logic analyzer, I took 000000010110100111011010 converters to decimal, the result is 92634. My zero factor is -46377. (In -46377 load results looking good.)

Question 1, long zero_factor = scale.read_average(); in library, why this zero factor always split in two?

Question 2, Why do zero factors values are got negative values?

Question 3, Why in the last load cell’s zero factors is -46377?

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microcontrolleranalogmeasurementload-celllogic-analyzerShareCiteEditFollowFlagedited yesterdayTransistor157k1111 gold badges169169 silver badges353353 bronze badgesasked yesterdaybuccno1111 bronze badge

  • 1This version of HX711 library for Arduino? github.com/bogde/HX711. – tlfong01 yesterday   
  • 1@tlfong01 yes for arduino. – buccno yesterday
  • (1) YZC-1B has a max capacity of only 40kg: fr.aliexpress.com/item/32225995715.html. (2) Please give exact specific links to your (a) library and (b) load cell. – tlfong01 19 hours ago   
  • (3) You might like to give us links to the references and tutorials you have been following. My references: (4) Why Is It Important To Calibrate Load Cell And Torque Sensors? – Futek futek.com/load-cell-calibration-services (5) tlfong01’s HX711 Testing and Calibration Results – 2019jan23 forums.raspberrypi.com/… (6) Rpi.com Forum Search “hx711 tlfong01” found 62 matches: forums.raspberrypi.com/… – tlfong01 18 hours ago   
  • You might like to give me a diagram or a photo of your Wheatstone or other bridge setup, likw this: forums.raspberrypi.com/… – tlfong01 18 hours ago   
  • 1@tlfong01 thank u for ur comment. My load cells datasheet here says 40 or 50kg capacity. ardu.dk/wp-content/uploads/2015/03/Vejecelle-YZC-1B.pdf. I use bogde’s library. I got a reference from this link; electroniclinic.com/… – buccno 13 hours ago
  • (1) Your electroniclinic.com tutorial uses a 1kg load cell, but your load cell is 50kg, which makes calibration a bit difficult. You see that I only experimented with load from 100g to 1kg, and I used standard weights to do the calibration. (2) I see the tutorial is a set of three tutorials, from Arduino to ESP8266 and ESP32 with WiFi one, and you are following the last, most complicated one. – tlfong01 7 mins ago   
  • (3) As you see that HX711 is just an ADC with high precision of 24 bits. This means that the input is simply an analogue voltage with a small value. That is why we need the Wheatsone bridge to sort of amplify many many times, to higher, say 0~3V3 by . (4) So you see I did the calibration is two big steps: (a) offline, annually, without the HX711, but only use a multi-meter. This is to make sure that you can calibrated the zero load point with no load, and half loading, and full loading, at half and full scale of the analog voltage range, 0 ~ 3V3. – tlfong01 3 mins ago   Edit   
  • (b) then do the calibration using HX711, or even better with a simple SPI ADC such as MCP3008, though with a very rough 12-bit resolution. This is sort of proof of concept, of the Wheatstone bridge thing. (5) You might also like to forget the strain gauge for now, and use a cheapy pressure sensitive sensor to learn the basic concepts. – tlfong01 just now   Edit   

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