Project Files of IoT Smart Weighing Scale with ESP32 - Proteus Simulation

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  IoT Smart Weighing Scale with ESP32 - Proteus Simulation Project V1.0
  The Engineering Projects - www.TheEngineeringProjects.com
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IMPORTANT LINKS
  The project tutorial (circuit, code, simulation results):
    https://www.theengineeringprojects.com/2026/11/iot-smart-weighing-scale-esp32-proteus-simulation.html
  The libraries this project is built from (each post has its own full download and tutorial):
    ESP32 DevKit V1 board:
      https://www.theengineeringprojects.com/2026/10/esp32-devkit-v1-library-for-proteus-v2-0.html
    HX711 module and load cells:
      https://www.theengineeringprojects.com/2026/10/hx711-load-cell-library-for-proteus-v1-0.html
    Membrane keypad 4x4:
      https://www.theengineeringprojects.com/2026/10/membrane-keypad-library-for-proteus-v1-0.html
    I2C LCD 20x4:
      https://www.theengineeringprojects.com/2026/10/i2c-lcd-20x4-library-for-proteus-v1-0.html
    5mm LED:
      https://www.theengineeringprojects.com/2026/11/5mm-led-library-for-proteus.html
    Resistor:
      https://www.theengineeringprojects.com/2026/11/resistor-library-for-proteus.html
    Laptop WiFi Monitor:
      https://www.theengineeringprojects.com/2026/10/laptop-wifi-monitor-library-for-proteus.html
    Mobile WiFi Monitor:
      https://www.theengineeringprojects.com/2026/10/mobile-wifi-monitor-library-for-proteus.html
  Support our free work: https://www.theengineeringprojects.com/donate

FILE STRUCTURE
ESP32-Smart-Scale-TEP-v1.0/
|-- Proteus Library Files/
|   |-- TEPESP32V1.LIB                                 36.6 KB   a part of the project -> LIBRARY folder
|   |-- TEPHX711.LIB                                   90.7 KB   a part of the project -> LIBRARY folder
|   |-- TEPI2CLCD20X4.LIB                             205.4 KB   a part of the project -> LIBRARY folder
|   |-- TEPKEYPAD.LIB                                 162.5 KB   a part of the project -> LIBRARY folder
|   |-- TEPLAPTOP.LIB                                  39.5 KB   a part of the project -> LIBRARY folder
|   |-- TEPLED5MM.LIB                                  21.8 KB   a part of the project -> LIBRARY folder
|   |-- TEPMOBILE.LIB                                  13.1 KB   a part of the project -> LIBRARY folder
|   |-- TEPRESISTOR.LIB                               306.9 KB   a part of the project -> LIBRARY folder
|-- Proteus Model Files/
|   |-- TEPHX711.DLL                                  313.5 KB   a model -> MODELS folder
|   |-- TEPKEYPAD.DLL                                 300.5 KB   a model -> MODELS folder
|   |-- TEPLCD.DLL                                    409.0 KB   a model -> MODELS folder
|   |-- TEPLED5MM.DLL                                 289.5 KB   a model -> MODELS folder
|   |-- TEPNET.DLL                                     2.89 MB   a model -> MODELS folder
|   |-- TEPRESISTOR.DLL                               311.0 KB   a model -> MODELS folder
|-- Proteus Simulation/
|   |-- ESP32_Smart_Scale.hex                          83.0 KB   the firmware
|   |-- ESP32-Smart-Scale.pdsprj                       38.5 KB   the project simulation
|   |-- TEPHX711.DLL                                  313.5 KB   copy of the model
|   |-- TEPKEYPAD.DLL                                 300.5 KB   copy of the model
|   |-- TEPLCD.DLL                                    409.0 KB   copy of the model
|   |-- TEPLED5MM.DLL                                 289.5 KB   copy of the model
|   |-- TEPNET.DLL                                     2.89 MB   copy of the model
|   |-- TEPRESISTOR.DLL                               311.0 KB   copy of the model
|-- Arduino Code/
|   |-- ESP32_Smart_Scale/ESP32_Smart_Scale.ino        12.6 KB   the sketch (source of the .hex)
|-- README.txt                                        ~10.5 KB   this file
Total: 9.95 MB (unzipped). The C++ source code of the models is not included.

WHAT IS IT?
  A complete IoT price-computing scale you can run in Proteus: an ESP32 DevKit V1 weighs with a load cell, takes the
  price per kg from a keypad, works out each item's price, adds the items to a bill and shows it all on an LCD and on
  a web page for a laptop or a phone.
    * HX711 module (HX711ADVTEP, U2) on 5 V: DT on D18, SCK on D19, read with the sketch's own code (24 bits, then a
      25th pulse for channel A at gain 128). U3 = the 5 kg bar load cell (LOADCELL5KGTEP, 1 mV/V) on its E+ / E- /
      A- / A+ (red, black, white, green). 429.5 counts a gram in theory and as measured with CAL 1 kg.
    * Membrane keypad 4x4 (KEYPAD4X4ADVTEP, U4): rows R1 - R4 on D13, D14, D27, D26 (inputs with pull-ups), columns
      C1 - C4 on D25, D33, D32, D4 (one at a time LOW), scanned 50 times a second.
    * I2C LCD 20x4 (I2CLCD20X4BLUEADVTEP, LCD1) at 0x27 on 5 V: SDA D21, SCL D22.
    * Green LED on D23 (the weight is stable) and red LED on D2 (overload), each through 220 ohm.
    * Laptop WiFi Monitor (PC1) and Mobile WiFi Monitor (MOB1) open the dashboard at http://192.168.1.101/.
  The keys: 0 - 9 and * (the decimal point) type a number; A = set the price per kg; B = tare; C = clear the number;
  D = add the item on the scale to the bill (only when stable); # = the bill is paid, start a new one.
  The weight is the average of the last 5 readings (half a second); STABLE when they lie within 4 g; OVERLOAD above
  5 kg (50 g of hysteresis either way). Its pages:
    /            the dashboard: the weight, the price, the bill with its items, the sales, the calibration, the events
    /tare        zero the scale (the same as B)
    /cal         calibrate with exactly 1 kg on the scale (after a tare with it empty)
    /pay         the bill is paid (the same as #)
    /data        everything as JSON

TEST STATUS
  Tested in Proteus 8 Professional on Windows 11, the run that made the tutorial's screenshots (simulation times):
    * 2 s: TARE - the scale is at zero; TEP-WiFi joined, the dashboard at http://192.168.1.101/; 0.000 kg, STABLE.
    * 1 kg (the HX711 pop-up): stable at 1000.0 g; CAL 1 kg from the laptop: 429 counts a gram (429.5 on the page).
    * The keypad: 3 * 2 0 A - "price set to 3.20 a kg"; 2.5 kg: stable at 2500.1 g; D - "item 1: 2.500 kg x 3.20 =
      8.00". 1 * 8 A - 1.80 a kg; 500 g: stable at 500.1 g; D - "item 2: 0.500 kg x 1.80 = 0.90"; the bill 2 items,
      total 8.90 on the laptop and the phone; # - "bill 1 paid: 2 items, total 8.90".
    * 5 kg, then +500 g: "OVERLOAD - more than 5 kg on the scale", 5.500 kg, the red LED on; 0 g: the overload gone.
    * A 100 g bowl, B: TARE; 1 kg in the bowl: stable at 900.0 g net.
  49 s of simulation took about 11 minutes on our PC with all the captures.

INSTALLATION
  1. Close Proteus. Extract the WHOLE zip file, for example to your Desktop.
  2. Copy the files from "Proteus Library Files" into the LIBRARY folder of Proteus, for example
     C:\Program Files (x86)\Labcenter Electronics\Proteus 8 Professional\LIBRARY
  3. Copy the files from "Proteus Model Files" into the MODELS folder (next to LIBRARY).
  4. Start Proteus. Press P in the schematic and search for ESP32 DEVKIT V1, HX711ADVTEP or KEYPAD4X4ADVTEP to check
     that the parts are there.

RUN THE SIMULATION
  1. Open "Proteus Simulation\ESP32-Smart-Scale.pdsprj". Keep the .hex and .DLL files beside it.
  2. Press Play. The scale tares itself with nothing on it (keep the load cell at 0 g), joins TEP-WiFi and shows
     0.000 kg on the LCD.
  3. Open the Laptop WiFi Monitor (PC1) or the Mobile WiFi Monitor (MOB1) and press Go. Press Refresh to update it.
  4. In the keypad's pop-up (U4) type a price, for example 3 * 2 0, then A.
  5. In the HX711's pop-up (U2) put a weight on the load cell (0 g, 100 g, 500 g, 1 kg, 2.5 kg, 5 kg, or the
     - / + buttons, 50 g and 500 g steps). When the LCD says STABLE, press D; press # when the bill is paid.
  Your own sketch: the source is in "Arduino Code". Install the TEP Boards for Proteus add-on from the ESP32 DevKit V1
  post, and the LiquidCrystal I2C library from the Arduino Library Manager; choose Tools > Board > ESP32 DevKit V1
  (TEP Proteus), export the compiled binary and set the board's PROGRAM property to the new .hex file. The same
  sketch runs on a real ESP32 Dev Module (power the HX711 from 3.3 V there and level-shift the LCD's I2C lines).

PROPERTIES USED IN THIS PROJECT
  U1 ESP32 DEVKIT V1   PROGRAM=ESP32_Smart_Scale.hex
  U2 HX711ADVTEP       (no changes: 10 SPS, channel A, gain 128)
  U3 LOADCELL5KGTEP    WEIGHT=0 (the HX711 pop-up sets it)
  U4 KEYPAD4X4ADVTEP   (no changes: BOUNCE 3 ms, PRESS 150 ms)
  LCD1                 ADDRESS=0x27
  PC1, MOB1            HOMEPAGE=http://192.168.1.101/

TROUBLESHOOTING
  * The weight reads negative: A+ and A- are swapped, or something was on the scale at the start-up tare.
  * The weight never says STABLE: the readings move more than 4 g; check the load cell's wires.
  * No key works: the rows and the columns are swapped (rows on D13 D14 D27 D26), or the rows have no pull-ups.
  * The LCD stays blank: its address is not 0x27, or SDA / SCL are swapped.
  * "Connecting to TEP-WiFi......" never ends: the .hex file is missing beside the project, or TEPNET.DLL is not in
    MODELS. Copy the files again and restart Proteus.

LICENCES
  * The project, the sketch, the parts (LIB files) and the models (DLL files) are made by The Engineering Projects
    and are free for learning and for your own projects. The models use only standard Windows libraries.
    The C++ source code of the models is not included; the source code is not included for any model.
  * The .hex file is built from the sketch with TEP Boards for Proteus, the Arduino add-on in the ESP32 DevKit V1
    download (its licences are listed in that download), and contains the library below. The HX711 and the keypad
    are read with the sketch's own code, no library.
  * Proteus is a product of Labcenter Electronics and is not included. ESP32 (Espressif Systems) and HX711 (Avia
    Semiconductor) are names of their owners; this project is not made or endorsed by them.

THIRD-PARTY LICENCES (compiled into ESP32_Smart_Scale.hex; the library's source is not included)
  LiquidCrystal I2C 1.1.2 - by Frank de Brabander, maintained by Marco Schwartz
  (https://github.com/marcoschwartz/LiquidCrystal_I2C).

VERSION
  V1.0 - the first release of the project.
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