Project Files of Split-Flap Display Library for Proteus V1.0 (Arduino + 28BYJ-48)

SPLIT-FLAP DISPLAY LIBRARY FOR PROTEUS - V1.0 (a 40-flap split-flap character module:
a 28BYJ-48 stepper turns the flap spool, a hall sensor finds home)
Designed by The Engineering Projects
www.TheEngineeringProjects.com

IMPORTANT LINKS
Article (read it first - pictures, step by step, every feature explained):
  https://www.theengineeringprojects.com/2026/11/split-flap-display-library-for-proteus-v1-0.html
Report a bug or suggest a feature (our forum):
  https://www.theengineeringprojects.com/forum/category/motor-driver-proteus-library
The demo runs on our Arduino UNO V4.0 (included) - working LEDs, RESET and a
built-in serial monitor - its own article:
  https://www.theengineeringprojects.com/2026/10/arduino-uno-library-for-proteus-v40.html
The demo's driver is Proteus's own ULN2003A (in every Proteus 8): nothing more
to install.
Support us (the libraries are free):
  https://www.theengineeringprojects.com/donate

FILE STRUCTURE
Split-Flap-Display-TEP-v1.0/
|-- Proteus Library Files/
|   |-- ArduinoV4TEP.LIB                              201.9 KB   TEP Arduino boards V4.0 (UNO) -> LIBRARY
|   |-- TEPSPLITFLAP.LIB                               20.5 KB   the library -> LIBRARY folder
|-- Proteus Model Files/
|   |-- TEPARDUINO.DLL                                883.5 KB   the Arduino board model -> MODELS folder
|   |-- TEPSPLITFLAP.DLL                              290.5 KB   the model -> MODELS folder
|-- Proteus Simulation/
|   |-- SplitFlap_Demo.hex                             28.8 KB   the demo firmware
|   |-- Split-Flap-Display-ULN2003A-ArduinoUnoV4.pdsprj   21.6 KB   the demo project
|   |-- TEPARDUINO.DLL                                883.5 KB   copy of the board model
|   |-- TEPSPLITFLAP.DLL                              290.5 KB   copy of the model
|-- Arduino Code/
|   |-- SplitFlap_Demo/SplitFlap_Demo.ino               8.5 KB   the demo sketch (source of the .hex)
|-- README.txt                                        ~18.0 KB   this file
Total: 2.59 MB (unzipped). The C++ source code of the models is not included.

WHAT IS IT?
A simulation model of the split-flap display module - the character module of
the clattering departure boards of railway stations and airports, rebuilt by
makers as clocks, word displays and message boards. Each module shows one
character: 40 flaps (blank, A - Z, 0 - 9, . - ?) hang on a spool; as the spool
turns, the next flap is pushed over a stop tab and falls, showing the next
character. Our model is the maker version: a 28BYJ-48 5 V stepper turns the
spool, a ULN2003 switches its coils, and a hall sensor with a magnet on the
spool finds home. Our own model:
  * The motor's coils between RED (the common) and ORANGE, YELLOW, PINK, BLUE
    (coils A - D) are in the circuit as their 50 ohm windings: a coil is on
    while its wire is pulled LOW (a ULN2003, transistors). The rotor follows
    them with the 28BYJ-48's physics - the back-EMF, the detents, the 63.68 : 1
    gearbox: 4075.8 half steps a turn, NOT 4096.
  * The spool is on the output shaft: 40 flaps, 9 deg each. Flap k shows from
    k x 9 deg until the next one falls; its centre is k x 9 + 4.5 deg. The
    flaps' load: the spool's friction (3 mN.m) and each next flap pushed over
    the tab (up to 8 mN.m more over the last half of every 9 deg).
  * Only forward: driven backwards, the flaps catch on the stop tab - the
    spool goes back 3 deg at most, then it is JAMMED and the coils' field
    slips past the rotor as lost steps.
  * Too fast loses steps: with the flaps and a ramp from 5 RPM it keeps up to
    about 17 RPM; above that it falls behind and shows a character the sketch
    did not ask for.
  * The hall sensor: HOME is its open-collector output with the board's 10
    kohm pull-up to VCC - LOW while the magnet passes (1.5 - 5.5 deg into the
    blank flap), HIGH everywhere else; it needs VCC (3 V or more).
  * The watch: SHOWING (with the move's flaps and time), HOME passes, JAMMED,
    lost steps, a stop next to a flap's fall (the sign of a steps-per-turn
    error), the wrong coil order, the supply.
The symbol shows the module from the front: the dark housing with the window
and its flap card (the two halves, the split between them and the hinge pins),
the 28BYJ-48 (the silver can, its two ears, the blue wire cap and its five
wires) and, on the right, the hall-sensor board (a small blue PCB, the black
sensor facing the spool, its own LED and the 3-pin header). At Run the window
shows the character on the spool, with the falling flap as it changes. The
plate, the coil LEDs A - D (lit in the wire's colour while the coil is on) and
the strip under the plate (SHOWS, RPM, HOME, OPEN PANEL) are TEP additions; the
real module has none of them.

ONE DEVICE (search "split-flap" or "flap" in Pick Devices):
  SPLITFLAPTEP   "Split-Flap Display V1.0"   (category Electromechanical >
                 Motors), model TEPSPLITFLAP.DLL
  The pop-up panel "TEP Split-Flap Display" opens at Run (and with OPEN PANEL
  on the strip) - the look of the TEP Serial Monitor. Tabs Display, Graphs,
  Event log and Check; gear and ? icons for Settings and Help; the palette
  icon switches the theme:
    Display    the state in big letters (FLIPPING, SHOWING 'H', JAMMED,
               LOSING STEPS, NO POWER); the flap showing and the spool's 40
               flaps in a ring with the home magnet marked; the live values
               (showing, flap, spool angle, speed, the coils' position, lost
               steps, the home sensor, the current); the coils over the last
               40 ms (the half-step pattern).
    Graphs     the flap showing (the home passes marked), the speed and the
               current over the last 5, 15 or 30 s. Live / Freeze.
    Event log  SHOWING ("SHOWING 'E' - from 'H' in 4.81 s, 37 flaps"), HOME
               passes, JAMMED, lost steps, a stop off the centre, power;
               filters All / Flaps / Warnings, Pause, Clear
    Check      Good for: a module that shows the wrong character, drifts a
               flap a turn, buzzes, jams or never finds home - the supply,
               the coils, the direction, the speed, lost steps, the home
               sensor, where it stopped in the flap, with tips
    Settings   theme, text size, open at Run, window size
    Help       report a bug, suggest a feature, article, updates, donate,
               forum; Copy diagnostics for a bug report

TEST STATUS
V1.0: verified in Proteus 8.5 on 29 Oct 2026 (the demo project as shipped: an
A4 sheet, an Arduino UNO V4.0 with its built-in monitor, Proteus's ULN2003A,
RV1 and the module; the pop-up open). What the runs showed:
  * The project loads and starts cleanly; the spool turns at 11.9 RPM until
    HOME goes LOW ("HOME - the magnet passed the hall sensor (HOME LOW) at 1.5
    deg, the blank flap"), stops on the blank flap, then RV1 (21 %) picks 'H':
    "SHOWING 'H' - from blank in 6.28 s, 48 flaps". The window shows each
    falling flap; the coil LEDs light in turn.
  * "text HELLO": "SHOWING 'E' - from 'H' in 4.77 s, 37 flaps" (all the way
    round - only forward), 'L' in 1.01 s (7 flaps), the second L stays, 'O' in
    0.50 s (3 flaps).
  * "rpm 25", "show Z": past about 17 RPM it falls behind - "lost 408 full
    steps (412 in all) - too fast for the 28BYJ-48 and the flaps' load"; it
    stops on 'P' with 492 full steps lost, 1.2 deg before the next flap falls,
    while the sketch prints "Showing 'Z'". The Check page: the coils stepped
    up to 25.0 RPM, the spool reached 12.0.
  * "rpm 12", "home": the next HOME pass puts it right - "SHOWING blank - from
    'P' in 3.07 s, 24 flaps"; "show Z": 26 flaps in 3.39 s.
  * "back": JAMMED - the spool goes back 2.7 deg and stops; "lost 32 full
    steps (528 in all) - against the jam".
  * "sync off", "turn 4096", "spin 3": the sketch counts 4096 half steps a
    turn; after 3 turns the module shows 'B' ("SHOWING 'B' - from 'A' in 15.17
    s, 121 flaps", 1.1 deg into it) while the sketch prints "Showing 'A'".
    "sync on", "turn 4076", "home", "show S": 'S' in 2.51 s, 19 flaps.
  Plus automatic checks on a PC, 0 failed: 21 on the module (4076 half steps
  at 12 RPM = 360.0 deg, 40 flaps fall, one HOME pass, no lost steps; blank to
  'A' on the flap's centre; the fastest clean speed with the flaps and a ramp
  17 RPM; 25 RPM without a ramp stalls and loses 1020 full steps; 200 half
  steps back move it 2.9 deg and jam; a stall and a jam add up; 5 x 4096 half
  steps end 8.9 deg past 5 turns - a flap too far; the home window; a stop
  next to a flap's fall is logged; 2 coils held: 163 mA; every event text
  fits); 3 on the pop-up pages rendered; the demo project read back from disk
  (87 checks: devices, pins, wires, labels, no wire through a part, no
  crossing).

INSTALLATION (about 2 minutes)
1. Close Proteus. Extract the WHOLE ZIP to a normal folder (e.g. Desktop).
2. Copy everything in "Proteus Library Files" (TEPSPLITFLAP.LIB and our
   Arduino library V4.0, ArduinoV4TEP.LIB) to the LIBRARY folder of Proteus,
   for example:
     C:\Program Files (x86)\Labcenter Electronics\Proteus 8 Professional\LIBRARY
   (on some PCs: C:\ProgramData\Labcenter Electronics\Proteus 8 Professional\
   LIBRARY - use the folder that already holds Proteus's own .LIB files).
3. Copy TEPSPLITFLAP.DLL and TEPARDUINO.DLL from "Proteus Model Files" to the
   MODELS folder (...\Proteus 8 Professional\MODELS).
4. Delete TEPSPLITFLAP.IDX from the LIBRARY folder if it is there.
5. Start Proteus. In Pick Devices (P) search "split-flap".

RUN THE DEMO
"Proteus Simulation\Split-Flap-Display-ULN2003A-ArduinoUnoV4.pdsprj" - keep the
.hex file and the DLLs beside the project.
  ARD1: Arduino UNO V4.0 running SplitFlap_Demo.hex, its serial monitor built
        in (window "TEP Arduino UNO - ARD1").
  U1:   Proteus's ULN2003A: 1B - 4B from D8 - D11 (labels IN1 - IN4), 1C - 4C
        to the module's ORANGE, YELLOW, PINK, BLUE; COM on +5V.
  DS1:  the module: RED on +5V; VCC on +5V, HOME to D2 (label HOME), GND.
  RV1:  10k pot on A0 (the character in knob mode; 21 %: 'H').
  1. Press Run. The monitor and the pop-up open (move them aside). The spool
     turns until the hall sensor sees the magnet, stops on the blank flap,
     then flips to the character RV1 picks.
  2. Turn RV1. Type in the monitor and press Send: text HELLO, show Z,
     rpm 25 then show Z, rpm 12, home, back, sync off, turn 4096, spin 3,
     sync on, turn 4076, home.
  3. Double-click DS1: START (the flap at power-up, 0 - 39).
  4. The pop-up: Display, Graphs, Event log, Check.

WIRING (the same idea on a real module)
  ULN2003 board   Arduino UNO / supply
   IN1 - IN4      D8 - D11
   +, -           5 V, GND (with the UNO's GND)
  28BYJ-48        the ULN2003 board's 5-pin socket (RED to its +)
  Hall sensor     VCC 5 V, GND, OUT (HOME) to D2 (INPUT_PULLUP is fine)
In the sketch (no library needed): the half-step table A, AB, B, BC, C, CD, D,
DA on IN1 - IN4, a step every 60 s / (RPM x 4076), only forward:
  const byte SEQ[8] = {0b0001, 0b0011, 0b0010, 0b0110, 0b0100, 0b1100, 0b1000, 0b1001};
  if (digitalRead(HOME_PIN) == LOW && lastHome == HIGH) pos = homeHalf();   // re-sync
REAL HARDWARE:
 * A 28BYJ-48 draws about 90 mA a coil at 5 V: through a ULN2003, never from
   the Arduino's pins. Release the coils when it stops: the gearbox holds the
   spool and the motor stays cool.
 * Count 4076 half steps a turn (64 x 63.68), not 4096 - and set the position
   again every time the home sensor fires: then no error can grow.
 * Only forward: to go back one character, go forward 39.
 * Ramp the speed from about 5 RPM; a 5 V 28BYJ-48 with the flaps keeps up to
   about 15 - 17 RPM (12 V versions go faster).
 * Hall modules (A3144, AH3364, KY-003) pull their output LOW at the magnet;
   check which pole they want - turn the magnet over if nothing happens.

THE DEMO SKETCH ON THE SERIAL MONITOR (SplitFlap_Demo V1.0, 9600 baud)
  show A     flip to A (forward only)        text HELLO  one character a second
  knob       RV1 picks the character          rpm 12      the top speed (a ramp)
  home       find the blank flap again        sync off    stop setting the position at HOME (sync on: again)
  turn 4096  the half steps a turn the sketch counts (the real one: 4076)
  spin 3     3 whole turns, back to the same character
  back       one flap backwards (it jams!)    help        the list
EXPECTED MONITOR OUTPUT
  Split-Flap Display demo - The Engineering Projects
  ULN2003A on D8 - D11, HOME on D2. 40 flaps, 4076 half steps a turn, forward only.
  Commands: show A | text HELLO | knob | rpm 12 | home | sync on | sync off | turn 4096 | spin 4 | back | help
  Homing - turning to the magnet
  Home found - the blank flap
  Showing blank
  Showing 'H'

PROPERTIES (double-click the part > Edit Properties)
  START      the flap showing at power-up, 0 - 39 (0 = blank, 1 = A ... 26 = Z,
             27 = 0 ... 36 = 9, 37 = . , 38 = - , 39 = ?; default 0)
Every run starts again from the properties.

TROUBLESHOOTING
* It does not turn (NO POWER): RED is not on +5 V, or the ULN2003A's inputs
  are not driven.
* It buzzes in place (WRONG ORDER): the coil wires are swapped - IN1 - IN4 =
  orange, yellow, pink, blue, in the half-step order A, AB, B, BC ...
* It shows a character the sketch did not ask for (LOSING STEPS): too fast,
  no ramp, or it was driven backwards - slow down and home again.
* JAMMED: the sketch drove the spool backwards - a split-flap only turns
  forward.
* It drifts a flap every few turns: the sketch counts 4096 half steps a turn,
  or it does not set its position at HOME.
* It never finds home: HOME is not on the UNO's pin, or the sensor has no VCC
  (the Check page says so).
* The part is not simulated: TEPSPLITFLAP.DLL is missing from MODELS and from
  the project folder. No UNO / no monitor window: TEPARDUINO.DLL, or click the
  UNO's USB port.
* The pop-up does not appear: click OPEN PANEL on the strip, or turn "Open the
  panel at Run" on its Settings page back on.

BUG REPORTS AND FEATURE REQUESTS
Please post them in our forum with a screenshot, the Serial Monitor text, the
simulation log and the pop-up's Copy diagnostics text:
  https://www.theengineeringprojects.com/forum/category/motor-driver-proteus-library

SUPPORT US
This library is free. If it saves you time, please support our work:
  https://www.theengineeringprojects.com/donate

LICENCES AND THIRD-PARTY NOTES
* The split-flap model (TEPSPLITFLAP.DLL), the symbol and artwork and the
  Arduino Library V4.0 (ArduinoV4TEP.LIB / TEPARDUINO.DLL) are made by The
  Engineering Projects. The model is an independent implementation written
  from the typical data of the 28BYJ-48 stepper, maker split-flap modules and
  hall-effect switches. The models use only standard Windows libraries; no
  Visual C++ redistributable is needed. The C++ source code is not included.
* The demo's ULN2003A is Proteus's own part.
* The demo's .hex is built from the demo sketch and the Arduino AVR core 1.8.6,
  which includes LGPL-licensed code; its source code is available at
  https://github.com/arduino/ArduinoCore-avr/tree/1.8.6
* Proteus is a product of Labcenter Electronics and is not included. Arduino is
  a trademark of Arduino SA. This library is not made or endorsed by any
  split-flap or motor maker, Arduino or Labcenter.

REBUILDING THE FIRMWARE (OPTIONAL)
The HEX file is supplied; Arduino IDE is not needed to run the demo. To edit
the sketch, open Arduino Code\SplitFlap_Demo\SplitFlap_Demo.ino, select
Arduino Uno and use Sketch > Export Compiled Binary. The sketch needs 10,478
bytes of flash (32 % of the UNO) and 420 bytes of RAM.

MODEL SCOPE AND LIMITS
Modelled: the 28BYJ-48's coils (50 ohm from RED, the driver's Darlington drop
and clamp diode, the back-EMF), the rotor, the detents and the gearbox; the
spool's friction and the flaps pushed over the stop tab; the jam backwards;
lost steps; the 40 flaps and the falling flap; the hall sensor's output with
its pull-up; the coil pattern, the order and the supply.
How it runs: the coils are 50 ohm windings in the circuit; a coil is on while
its wire sits more than half the supply below RED, each change time-stamped
where the voltage crossed; between two analog points (1 ms at most) the rotor
follows that history in 10 us steps.
Not modelled: the flaps' own flutter and sound, the magnet's pole (any magnet
works), a 12 V motor, more modules on one bus (each module is one part: put
several side by side, each on its own driver).

VERSION
TEP Split-Flap Display library V1.0 (Oct 2026). Device SPLITFLAPTEP
(TEPSPLITFLAP.LIB / TEPSPLITFLAP.DLL). Demo sketch SplitFlap_Demo V1.0. Demo
driver: Proteus's ULN2003A. Demo board: ARDUINO UNO V4.0 (TEP Arduino Library
V4.0) with its built-in serial monitor.