First, we need to calibrate the load cell and store that value on EEPROM, for that, go to file > examples > HX 711_ADC, then select the calibration code. Next, we will explore calibration and test the load cell as a weighing scale. N.B. This module uses 24 high precision A/D converter chip HX711. Arduino, for instance, introduces a lot of noise. In any case you cannot ask for low voltage power supply with low cost ADC with low cost load cells. !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if( !d.getElementById(id) ){js=d.createElement(s);;js.src="//";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); © 2021 The MechTech Place — Powered by WordPress. Secondly, my advice is to check that the wiring is working with a multimeter: check the continuity of circuitry and then check if the load cell is powered with 2.5 Volts. So instead of measuring resistance, we can measure voltages easily. yes, 24bit is too much. The conductive pattern of the strain gauge is made out of copper, this wire will have a certain area and length, so these two units will give the resistance of the wire. The load cells plug into this board, and this board tells the Arduino what the load cells measure. Is this affects arduino micro. Hello,I have used ur circuit with 22k pot and cannot get load cell calibrated correctly.Why?? The input circuit can be … What to do? I sent them to you in zip format, ready to be sent to PCB manufacturers. The easiest way to get a weigh reading from these to an Arduino is to use the HX711 amplifier module. If you are managing to sense forces both positive and negative, you have to select a symmetric path, so if you load 1 kilogram, you have to provide a -1kg loading too. Hi Alberto this is a great Tutorial, but i need more of your help. Dear Thomas, First of all, if you like to make it as easy as possible, pick the breadboard! We have I2C LCD, so connect SDA to A4 and SCL to A5. Processor? Nonetheless, this module is commonly being used to measure weight. Follow @lelliollo Your email address will not be published. You have any idea how I can improve the accuracy so I can use a lower bit (cheaper) ADC? The HX711 library is for taking the load cell values. Secondly, the real big problem is how to design a proper powder receptacle for your application. The 2.5v becomes 0.8v and the 3.3v becomes 1.4v (based on the max output of the INA being 4.2v). Now imagine that the right-side cell is mounted to the base and the left side is where the load is placed, this configuration deforms the strain gauge load cell because of the giant hole in the middle. Then started to read the values from loadcell using loadCell.begin() function, after that, we read the EEPROM for the calibrated values, we do that by using the EEPROM.get() function. The SparkFun Load Cell Amplifier is a small breakout board for the HX711 IC that allows you to easily read load cells to measure weight. Cons: 5kg load cell - Load cells are specially shaped metal parts that have strain gauges glue to them. 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Thank you for this instructional guide, it has cleared up so many questions I had. Well, if you replicate the circuit shown in that page, you will have similar (or even better) performance compared to the one of INA 125P. The load cell has four wires which are red, black, green, and white. Here are some of my load cell specs; Hi Alberto, is there a replacement for an INA 125p? Most of the times excitation between 5 or 10V is just perfect (using a 9V battery is a good practice). In any case you need to calibrate both the circuits, because of stocasticity: even if nominally the two circuits (and the two load cells) are the same, they're behavior is not identical! You are at the right page :) This is 5kg load cell that comes with HX711 amplifier board. HX711 or INA 125, and why you choose that component ? Chinese products may be good or not. Thanks for your reply! By connecting the amplifier to your microcontroller you will be able to read the changes in the resistance of the load cell, and with some calibration you’ll be able to get very accurate weight measurements. First thing I'll invite you to take a look and download INA 125 P datasheet, since it will be useful later. The load cell must also be accurately wired to the HX711 to ensure that the appropriate strain gauge leads are used to approximate the weight given by the load cell. Same goes when I apply load - it also seems like the voltage of the INA drops from time to time - e.g. If the difference between set weight and measuring weight is greater than or equal to 50gms, the buzzer beeps with a 200-millisecond delay (slowly). 2) is the INA125P working? Would you mind sending me the Gerber files for your pcb as you offer? In a previous article, we have made projects like Raspberry Pi Based Weight Sensor and IoT Smart Container with Email Alert and Web Monitoring using the popular HX711 load cell amplifier module. let's go directly to your application: HX711 is an integrated conditioner and digital converter hence it is one of the best options to work with strain gage load cells. But the Due (like the Zero which I use) has a maximum input of 3.3V and the zero level in this circuit is 2.5V which is at approximately 75% of the range and leaves less than 1000 of the 4096 levels. I reviewed your introduction information, you are impressive. The dynamic range of the full load cell is reduced. EEPROM is the inbuilt library of Arduino ide, which is used to store values in EEPROM and the LiquidCrystal library is for the l2C LCD Module. This is JB ( from Bangalore, India. i am not getting output value as zero when zero force is applied ...i am getting values which is greater than zero where the value is changing in last three digit out of 5 digit value ..suppose i should get a value of XX200 when the force applied is zero but i get values which is XX600 or around that the problem is after the force become zero i am not getting XX200 and the values keep on chnaging with out greater than XX500 when the force applied is zero can u help me to know where i am going wrong as the output is not zero and keep on changing when force is zero because of that i am not able to keep any offset value to subtract with given value when the force is zero.... When I put 250g on strain gage the value changed a little (strain gage range is 2kg), but when i put less than 125g the value didn't change. The datasheet for my bridge requires 10V excitation voltage, I would like to use as much excitation voltage as possible to get clean signals at low loads. I've looked at the HX711 IC which looks promising, but I'd like to get your thoughts, pitfalls etc. For common economic load cell the gain potentiometer should be set to a value between 50 and 120 Ohm (to check this, use a multimeter and read the resistance between pin 8 and 9 of the INA 125P). (see shock, Hello John, And temperature drift is the main problem affecting accuracy of strain gages. i have a ZC-A 300kg load cell from a functional scale. So let's see if I'm understanding you, would I ground pin 5 to pin 3 if I were wanting to measure only a tensile load. Thanks for reply, I have got lots of information, can you please let me know how to perform a design calculations of loadcell like signal at each point , noise factors and power calculation to justify it doesn't heat up. Click here for instructions on how to enable JavaScript in your browser. Would this be use for bipolar output only? However they seem to speak to much "electronisch" in that data sheet, so I prepared some hacking for you. But this voltage change is still very small, so to increase that, we need to use the HX711 module. 2) if you use a +5V supply without pseudogrounding, as shown in many arduino forum tutorials, you don't get a linear amplification. Don't worry, I'm not in discomfort with giving advices Can you please share me same on On the Vin+, i have connected the green wire from the load cell (on 5V power supply, the Vin+ is 1.22V) You can use it with all load cells available on the market. We will wire the INA 125 P in the pseudoground configuration. After search for others OP's, I saw their prices and I chose the INA125p, because it was more cheap and it will arrive in one day, I will use your circuit, I made some simulations and I saw that he can give the precision that I need ( 1Kg now), so I hope that everything works If you prefer, you can replace it with a common connector block or with dedicated breadboard connectors. What do you think ? Hi, in my project I use 3 wire load cell (like this (3wire 50kg) but mine are purchased from ebay) and HX711 for weighing. For instance all the INA family is appliable to strain gages. How to get out of such a mess? However do not go below 150 Hz. I would like to buy 2 of your PCB's. I just have a question: when wiring everything up, what do the red dots on your diagram represent. I'm still waiting on the delivery of my 16 bit ADC from adafruit (ADS1115), that should be more than enough for my use case, according to your helpful formula. This week I'll graduate for my masters, then I will have time to upload a tutorial on fully symmetric wiring for the INA125P, forgive me I have more questions However Arduino Uno works perfectly with this circuit, so I believe you will not encounter any particular problem in usign a load cell. Are you sampling the signal with a good quality ADC? I know you don't want to advertise but I was wondering if you could provide the names of a couple of companies you have dealt with in the past that provided you with good PCB boards. If you want an "easy" and low cost option for data acquisition, try Measurement Computing: If the answer is "yes" you'd better go further with reading this. 100 grams, but with an accuracy of 0.1 grams), so I thought that this one is suitable for me. Then defined integers for different pins and assigned values. They are always super nice! This Arduino based electronic scale is perfect for measuring the weights up to 10kg (we can increase this limit by using a higher rated loadcell). So, I'd be very grateful if you could let me see your gerber files, I'm sure they'll be very instructive and save me some grief. HX711 In ina128p output the voltage is 100mV when not have charge until 20 lb, after, works normally. For this purpose, we useHX711 amplifier sensor. (Not saying it is too much that the board bursts, but it is too much to get a low level of noise) consider to power the INAs with an external 5V - 1A power supply (in your case batteries could be a good choice). Is this circuit use to measure torque of oscillation.. A strain gauge is a component that is used to measure strain. Click here for instructions on how to enable JavaScript in your browser. To make it short, I can give you a rule of thumb: if you need n levels for your measurements application, you need to provide at least 3*n levels at your ADC, to let you reach the desired precision for your application. If you don't mind me asking, do you think it would be possible to build a DAQ from Arduino? You can track the status of your order and they are fast. Which is why that is the point that suffers deformation when a load is placed on the mount side. Can you send me Gerber files for single and 8 channels to my email That is a normal thing. A brief, incomplete, but yet practical and correct handbook for begginers is this one The total effective measurable range drops from (3.3-2.5= 0.8v) to (1.4 - 0.9 = 0.6v) Because i now, that when i try to make this stuff i will get noise and other problem. Could you send for me? I've build your circuit on a breadboard and it works perfectly. Plug and play for this application! Very good tutorial, thanks! In the case I have more than one ckt, how do you suggest me to calibrate G tho be equal in each ckt? Thanks man, nice explanation. I am curious about one thing I understand that the maximum excitation for the load cell shouldn't be used (10-15 volts for my case). Wiring scheme of the INA 125 P for bidirectional force sensing. The HX711 is easily wired to the Arduino using any two digital or analog pins. I would love to take you flying. 3) you set a low level of gain with Rg, Hi Alberto, thanks for a great tutorial. Load cell wires hooked up to the HX711 Amplifier board Once the load cell is is hooked up to the amplifier, you can hook up VDD, VCC, DAT, CLK, and GND to a microcontroller such as a RedBoard or Arduino board. Thank you for the Gerber files. Helping me with that would be great for a beginner like me. The core of this project is a wonderful and flexible Wheatstone bridge amplifier IC called INA 125 P made by Burr Brown - Texas Instruments. Once you wired everything as shown before, you can connect your DAQ board to the PC. I'm glad for your appreciation! Where would I possibly have gone wrong? thanks in advance . This is true. how to connect myrio instead of daq for load measurement?? My suggestion in your case is to go in any case for a symmetric supply since it is fundamental for measurement precision, even if you sense forces mono-directionally. Really good experiment and tutorial Alberto. your situation can be generated by 3 different problems: It's only "things I've been working with lately") such as those . Correlated noise is killed most of the times by low pass filters. Your choice is really good for high precision measurements since noise plays a relevant role into determining resolution (and accuracy as well). Cons: +-12v (i used a computer source but practical delivers +-14v aprox). With help of the Arduino PULL UP function, we set the pins to a logical high at normally. -fluctuations: fluctuation is an effect of noise which may be white noise (and in this case it's normal since every circuit has one) and correlated noise (which is the effect of oscillattory behaviour of power supply, typically 50Hz noise from AC mains). Congratulations for you amazing tutorial. To make this project as simple as possible, we have used very generic components that you can find in any local hobby store. Which parameter that i need to change? I have tal220 10kg load cell that I using for an automatic dog feeder. I have been playing around with this circuit and am using a 10 turn 10kOhm potentiometer. I am building a product in which I am making bi-axial strain measurement would love to have your feedback on my project. Typically when operating load cells at 10V, I use a +/-12V power supply which can be derived from a common 24V DC power supply using a virtual ground. And how about using LTC2400 as an ADC for the scale? Really good analog circuitry. 2) you've messed up with ina128 wiring, in particular it seems to me that you are not running the IC under symmetric power supply (+/- 5V) [remember that the ina128 should work with symmetric voltage sources] I have a HX711 board on the way, for anyone who is interested in details on the HX711 the website I used was Do you have a link to the whole article? Note: VCC is the analog voltage to power the load cell. In fact, since the circuit doesn't have a properly set zero level (the thing which IAref pin is made for) altering the gain will alter also the output when no load is applied. I have reread this post and 2 years later makes more sense.Thanks. I am not too worried about heat or temp deviation, just getting a clean clear signal especially as load changes from tension to compression. In S1 you will sense a tension proportional to load cell load plus a voltage offset of 2.5 V. A couple of words should be spent on how to connect 4 wires load cells. finally, we attached the main switch to the side of the balance and that's it. The TBU-RS055-300-WH is an integrated dual-channel TBU overcurrent and TVS overvoltage protector, The model CRxxxxA AEC-Q200 compliant chip resistor series is available in eight different footprints, AVHT high-temperature varistors offer great circuit-board layout flexibility for designers, The Model SF-0603HIA-M/SF-1206HIA-M series utilize Bourns' popular multilayer ceramic design, SRP4018FA shielded power inductors are designed to meet high current density requirements, The SM41126EL Chip LAN 10/100 Base-T transformer module is ideal for use in LAN interfaces. We did that using if conditions, we have a total of three conditions. Or do you recommend using +/- 6V using my 12V supply? ByRajesh *Excitation(recommended)=10V to 12V DC Please send me files Now i have arduino uno/mega/due and japan load cell with rated output 2mV/V. Sampling rate is not important in this case. In this case by plugging Ia_ref pin in the power supply pin you make the IC believe that the ground is 2.5V (so called pseudogrounding operation). Now, we need to place the known weight on the balance, in my case, that is 194gm. I am asking a question, which sensor is suitable for pressure measurement(I find the weight of CNG ) this is my project to design digital CNG indicator for monitoring to display the value of CNG in kilogram, please send datasheet of pressure sensor? (it's for my degree project, this week) My e-mail address:, am final year student of electrical engineering,My project is to design CNG and petrol indecator for fuel monetering i am use loadcell for petrol (resistive strain gauge ) and also load cell use for CNG ) with the help of Arduino and LCD display value in the form of digital ,Sir simulate this project by Proteus softweare or other softweare... i am wating. Thank you for an excellent tutorial. Using PLC it may interesting but not necessary to power up the INA125P with higher voltage supply (let's say V++ equal to 9V instad of 5V). You should select a load cell having a full scale loading of about 800-1000 grams with a rated output of about 2 mV/V Thanks, Hello.Can u please contact me via e mail to sort out problem with my load cell.Thanks John, Email me a full description of your problems, then we'll see if I can help you. Thank you for your appreciation. Thanks. With the pseudoground mode, in fact, you let the amplifier see the +5V of power supply as a -2.5V/+2.5V symmetric power supply. As a consequence, the procedure is really resilient to system noise and leads you to have a very repeatable instrument (in other words calibration is valid for a long long time). People who share their knowledge are the people who make the world a better place. I'm new to load cells, but still looking at making a digital scale for measuring powders, so I'll only need around 30 grams max. The image below will give you an idea about the components. I designed this circuit for bidirectional sensing. First, we calculate the difference between set weight and measuring weight, then stored that value in the variable k. 1. thank you.. Well, INA125P is the only taylor made solution for such a task, so there is not a true substitute. Now I don´t understand really well how i can get the 10v supply from the Ina128p because a measure the present value and i don't have any voltaje. What is the limit? Reference voltage is less important as it is not sampling a voltage from an unrelated circuit - the supply to the wheatstone bridge is the same supply as the ADC (if it’s wired correctly, anyway) and hence it’s … The load cell is a straight bar load cell … Thanks again for the wonderful tutorial Alberto. I did this for you and, if did everything correctly, you only need the value of the gain equivalent resistance Rg to get the whole amplifying gain. It won't be a problem as long as you filter the signal (but you should do it anyways IMHO), since nowadays stepups switching regulator work around the MHz switching frequency (you have a band limited uncorrelated noise, noise problems becomes dramatic only when you have correlation between signal and noise in the full bandwidth). However, since noise exists, it is normal that the signal floats. HX711_ADC loadcell function is for setting the Dout and clock pin. My suggestion, coming from direct experience, is to use dedicated products from SMD Sensors (once again, nobody pays me for suggestions. Connect one end of push buttons to D3, D8, D9, and other ends to the ground. Required fields are marked *. Currently you have JavaScript disabled. se all'uscita dell'INA125 hai 64mV è c'è qualcosa che non va (in teoria a carico uguale a 0 hai 2.5V), se, invece, intendi che, una volta che hai alimentato la cella di carico, questa ti butta fuori 64mV con su il carico, può essere una cosa reale. I will still need to do a little more homework on the load cells though. That is, in the beginning, the display shows ARDUINO BALANCE as welcome text, and after two seconds, it will clear and display the measuring weights. In fact, no matter how good your setup is, every transducer suffer from uncorrelated and correlated noise. Remember that ADC (especially S/H low cost devices) may introduce a lot of noise (so random signal fluctuations). So you should not exceed it in order to operate your load cell in "safe mode". I have a 12V regulated power supply that I bought for the load cell, should I do away with the 12V power source and use the 5V from my DAQ to power my load cell?