Project Files of X27.168 Speedometer Gauge Library for Proteus V1.0 (Switec X25)

X27.168 SPEEDOMETER GAUGE LIBRARY FOR PROTEUS - V1.0 (the gauge stepper with a speedometer dial and a pop-up panel)
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/2026/10/x27-168-speedometer-gauge-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, no Virtual Terminal to wire - its own article:
  https://www.theengineeringprojects.com/2026/10/arduino-uno-library-for-proteus-v40.html
Support us (the libraries are free):
  https://www.theengineeringprojects.com/donate

FILE STRUCTURE
X27.168-Speedometer-Gauge-TEP-v1.0/
|-- Proteus Library Files/
|   |-- ArduinoV4TEP.LIB                              201.9 KB   TEP Arduino boards V4.0 (UNO) -> LIBRARY
|   |-- TEPX27.LIB                                     32.0 KB   the library -> LIBRARY folder
|-- Proteus Model Files/
|   |-- TEPARDUINO.DLL                                883.5 KB   the Arduino board model -> MODELS folder
|   |-- TEPX27.DLL                                    325.5 KB   the model -> MODELS folder
|-- Proteus Simulation/
|   |-- TEPARDUINO.DLL                                883.5 KB   copy of the board model
|   |-- TEPX27.DLL                                    325.5 KB   copy of the model
|   |-- X27_Speedometer_Demo.hex                       21.4 KB   the demo firmware
|   |-- X27-Speedometer-Gauge-ArduinoUnoV4.pdsprj      24.1 KB   the demo project
|-- Arduino Code/
|   |-- X27_Speedometer_Demo/X27_Speedometer_Demo.ino    5.1 KB   the demo sketch (source of the .hex)
|-- README.txt                                        ~17.8 KB   this file
Total: 2.66 MB (unzipped). The C++ source code of the models is not included.

WHAT IS IT?
A simulation model of the X27.168, the small stepper motor behind the needles
of car instrument clusters (the Switec X25 family) - the part makers use for
speedometers, tachometers and fuel gauges. Our own model, not a symbol on top
of Proteus's motor:
  * Two coils, 260 ohm each, whose axes sit 60 deg apart, a two-pole magnet
    rotor and a 180 : 1 gear train to the needle. The 6-state partial-step
    sequence (0x9, 0x1, 0x7, 0x6, 0xE, 0x8 on A+ A- B+ B-) turns the field 60
    deg a state: one step = 1/3 deg of the needle, 945 steps = 315 deg.
  * Four Arduino pins drive it directly: about 17 mA a coil at 5 V (a pin can
    give 20 mA). The current comes from the pins in the circuit - an ammeter or
    a probe on a coil wire shows it.
  * The needle has real end stops at 0 and 315 deg. Like every gauge sketch,
    the demo zeroes at power-up: 1000 steps down, the needle pushes against
    its 0 stop and the positions count from there.
  * The rotor is a tiny magnet with inertia and friction: it follows 800 us
    steps from rest and about 1400 steps/s (470 deg/s) with a ramp. Steps
    that come too fast without a ramp - or a finger on the needle - are LOST:
    the needle then shows the wrong value until the next zeroing, exactly the
    fault you meet on the bench.
  * The mistakes it names: lost steps (too fast, or the needle held), a coil
    wire off (only one coil carries current), more current than a pin should
    give, steps beyond the end of the scale.
The symbol: a white plate with the speedometer dial (0 - 240 km/h over the 315
deg sweep - property SCALE), the red-orange needle turned to the simulated
angle, the black X27.168 motor body with its four pins A+ A- B+ B- on top. A
click on the dial puts a finger on the needle (a click again lets go). The
plate, the dial, the coil LEDs A and B (green while the coil's current flows
from + to -, red the other way) and the strip under the plate (KM/H, DEG,
STEPS and OPEN PANEL) are TEP additions; the real X27.168 is the bare motor.

ONE DEVICE (search "X27" or "gauge" in Pick Devices):
  X27168TEP   "X27.168 Speedometer Gauge V1.0"   (category Electromechanical >
              Stepper Motors), model TEPX27.DLL
  The pop-up panel "TEP X27.168 Speedometer Gauge" opens at Run (and with OPEN
  PANEL on the strip) - the look of the TEP Serial Monitor. Tabs Gauge, Graphs,
  Event log and Check; gear and ? icons for Settings and Help; the palette icon
  switches the theme:
    Gauge      the state in big letters (SHOWING 180 KM/H / MOVING UP / LOSING
               STEPS / AT THE 0 STOP - THE ZEROING / RELEASED), the dial - the
               red needle and an orange mark where the coils ask -, the live
               values (speed, needle, position, step rate, target, lost steps,
               coil A, coil B) and the two coil currents over the last 20 ms:
               the 6-state step pattern. The toolbar: "Hold it" - a finger on
               the needle.
    Graphs     the needle and where the coils ask (deg), the step rate (steps/s)
               and the coil current over the last 2, 6 or 15 s. Live / Freeze.
    Event log  coils on, the zeroing, every move ("HOLDING at 236.7 deg (710
               steps) - from 6.5 deg, the move peaked at 1399 steps/s"), the
               stops, lost steps, the warnings; filters All / Moves / Warnings,
               Pause, Clear
    Check      Good for: a needle that does not move, only twitches, shows the
               wrong speed, drifts or never settles at 0 - the coils, the
               current, the steps, the rate, the zeroing and lost steps, each
               with a verdict (green = fine, amber = check, red = wrong)
    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 28 Oct 2026 (the demo project as shipped: an
A4 sheet, an Arduino UNO V4.0 with its built-in monitor, the gauge on D4 - D7,
RV1 on A0; the pop-up open).
What the runs showed (the needle's angle as the model computed it):
  * The project loads and starts cleanly. The zeroing: 1000 steps down, "AT
    THE 0 STOP", then "ZEROED" at 1.09 s; the self-test sweep: the needle to
    315.3 deg and back to 0.3 deg, peaking at about 1400 steps/s (467 deg/s).
  * RV1 at 75 %: "Pot 768 -> 180 km/h = 709 steps = 236.3 deg"; the needle
    settled at 236.7 deg (one step above the count - after the zeroing the
    rotor sits on the first field position above the stop), coils -16.7 /
    16.7 mA, both coil LEDs lit, 0 lost steps.
  * speed 60: 236 steps, the needle at 79.0 deg. sweep: up to 315 deg and back
    (the Graphs page: the needle on top of the target). knob: back to 236.7.
  * Hold it (a finger on the needle) and speed 30: the needle did not move,
    the coils ran on - "lost 588 steps (594 in all, 198.0 deg)" in red. Let
    go: the needle stayed at 235.7 deg - the sketch thinks it shows 30 km/h.
    zero, then knob: back at 236.7 deg, 0 lost steps.
  * The pop-up: Gauge, Graphs (2 / 6 / 15 s), Event log, Check - all four pages
    followed the run.
  Plus automatic checks on a PC, 0 failed: 19 on the gauge (the zeroing from
  120 deg ends at 0.3 deg; the demo's start with no rest after the zeroing;
  90 steps at 800 us from rest = 30.02 deg; 3 steps = 0.997 deg; 16.1 mA a
  coil; the ramped sweep: 900 steps = 300 deg, top 1701 steps/s, nothing lost;
  300 steps at 350 us without a ramp lose 282 steps; 2000 us steps are fine;
  the upper stop at 315.4 deg; a finger holds the needle); 3 on the pop-up
  pages rendered; the demo project read back from disk (63 checks: devices,
  pins, wires, labels, no wire through a part, no wire 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" (TEPX27.LIB, and our Arduino
   library V4.0, ArduinoV4TEP.LIB, with the ARDUINO UNO V4.0 used by the demo)
   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 TEPX27.DLL and TEPARDUINO.DLL from "Proteus Model Files" to the
   MODELS folder (...\Proteus 8 Professional\MODELS).
   ArduinoV4TEP.LIB and TEPARDUINO.DLL are the files of our Arduino Library
   V4.0 - if you have it, they are the same.
4. Delete TEPX27.IDX from the LIBRARY folder if it is there (Proteus makes a
   new index).
5. Start Proteus. In Pick Devices (P) search "X27".

RUN THE DEMO
"Proteus Simulation\X27-Speedometer-Gauge-ArduinoUnoV4.pdsprj" (an A4 sheet) -
keep the .hex file and the two DLLs beside the project.
  ARD1: Arduino UNO V4.0 running X27_Speedometer_Demo.hex, its serial monitor
        built in (window "TEP Arduino UNO - ARD1").
  M1:   the X27.168 gauge - A+ on D4, A- on D5, B+ on D6, B- on D7 (by the
        net labels D4 - D7 above both parts).
  RV1:  a 10k potentiometer (POT-HG) on A0 - the speed: 0 - 240 km/h.
  1. Press Run. The monitor and the gauge's pop-up open (move them aside -
     they open over the schematic). The needle zeroes, sweeps to the end of
     the dial and back, then goes to the pot's speed (RV1 at 75 %: 180 km/h).
  2. Click RV1's arrows: the needle follows with a smooth ramp.
  3. Type in the monitor and press Send: speed 120, step 30, sweep, zero,
     knob - see THE DEMO SKETCH.
  4. Click the dial (or "Hold it" on the pop-up): a finger holds the needle.
     Type speed 30 - the steps are lost. Let go, type zero and knob.
  5. The pop-up: Gauge, Graphs (try 15 s and Freeze), Event log, Check.
Closed a window? The monitor: click the UNO's USB port; the pop-up: OPEN PANEL.

WIRING (the same in Proteus and on a real board)
  X27.168 pin     Arduino UNO
   1 (A+)         D4
   2 (A-)         D5      coil A between pins 1 and 2
   3 (B+)         D6
   4 (B-)         D7      coil B between pins 3 and 4
  Potentiometer   the ends to 5V and GND, the wiper to A0
Any four digital pins work. The sketch writes the six states itself (the same
order as the SwitecX25 Arduino library), so no extra library is needed:
  const byte MAP[6] = {0x9, 0x1, 0x7, 0x6, 0xE, 0x8};   // bit0 A+ .. bit3 B-
  one step up = the next state, one step down = the one before
  zero at power-up: 945 + 55 steps down at 800 us, then position = 0
  move with a ramp: 3000 us a step at the start and the end, 600 us between
REAL HARDWARE:
 * The coils take about 19 mA each at 5 V: the pins drive them directly.
   Driver chips (VID6606, AX1201728SG) add microstepping for a smoother,
   quieter needle - this model expects the 6-state steps from four pins.
 * Zero at every power-up: a gauge never knows where its needle is.
 * Never jump at full speed from rest: ramp up and down, or steps are lost.

THE DEMO SKETCH ON THE SERIAL MONITOR (X27_Speedometer_Demo V1.0, 9600 baud)
  speed 120     show 120 km/h (0 - 240) and stay (the pot is ignored until knob)
  step 30       30 steps up from the target (step -30: down; kept in 0 - 945)
  sweep         the self-test: to the end of the dial and back
  zero          1000 steps down against the 0 stop, then count from 0
  knob          follow the pot on A0 again
  help          the list
EXPECTED MONITOR OUTPUT
  X27.168 speedometer gauge demo - The Engineering Projects
  A+ D4, A- D5, B+ D6, B- D7. The pot on A0 is the speed: 0 - 240 km/h.
  Commands: speed 120 | step 30 | sweep | zero | knob | help
  Zeroing: 1000 steps down against the 0 stop...
  Self-test: the needle to the end of the dial and back
  Ready - turn the pot
  Pot 768 -> 180 km/h = 709 steps = 236.3 deg

PROPERTIES (double-click the part > Edit Properties)
  SCALE   the speed at the end of the dial in km/h (default 240); the dial's
          numbers follow it - 120 for a small scale, 300 for a fast car
  START   the needle's angle at the start in deg, 0 - 315 (default 0): start
          it at 120 to watch the zeroing bring it back
Every run starts again from the properties. The demo's UNO (ARDUINO UNO V4.0):
PROGRAM X27_Speedometer_Demo.hex, MONITOR YES (the built-in monitor), BAUD
9600, AUTOOPEN YES, BOOTLOADER YES.

LINKS.INI (OPTIONAL)
The Help page cards of the pop-up open web pages. To point them somewhere else
without a new DLL, put a text file named links.ini next to TEPX27.DLL with
lines KEY=URL, for example:
  ARTICLE=https://www.theengineeringprojects.com/...
Keys: WEBSITE, FORUM, BUG_REPORT, FEATURE_REQUEST, ARTICLE, USER_GUIDE,
UPDATE_CHECK, DONATE. Only http:// and https:// links are used; lines starting
with # are comments.

TROUBLESHOOTING
* The needle never moves and the pop-up says RELEASED: no coil current - the
  pins are not OUTPUTs, the wires go to other pins than the sketch's, or the
  sketch never writes a state.
* The needle only twitches back and forth: two wires of one coil are swapped
  with the other coil's (A+ / B+ crossed) - the field jumps instead of turning.
* "only coil A carries current": coil B's wires (B+ / B-) are off.
* The needle shows the wrong speed: steps were lost - the Event log and the
  Check page show how many. Ramp the moves, and zero at power-up.
* The needle sits at an end: steps beyond the scale (more than 945), or the
  sketch never zeroed and counts from the wrong place.
* The part is not simulated / the needle never turns: TEPX27.DLL is missing
  from MODELS and from the project folder. No UNO / no monitor window:
  TEPARDUINO.DLL is missing, 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

WEBSITE
  https://www.theengineeringprojects.com/

LICENCES AND THIRD-PARTY NOTES
* The gauge model (TEPX27.DLL), the symbol and artwork and the Arduino Library
  V4.0 (ArduinoV4TEP.LIB / TEPARDUINO.DLL, with its built-in TEP Serial Monitor
  Advance) are made by The Engineering Projects. The model is an independent
  implementation written from the typical data of the X27.168 gauge stepper.
  The model uses only standard Windows libraries; no Visual C++ redistributable
  is needed. The C++ source code is not included.
* Arduino UNO V4.0 (ArduinoV4TEP.LIB / TEPARDUINO.DLL, our Arduino Library
  V4.0 - its microcontroller is Proteus's own AVR model): The Engineering
  Projects, https://www.theengineeringprojects.com/2026/10/arduino-uno-library-for-proteus-v40.html
* The potentiometer is Proteus's own POT-HG.
* The .hex file 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. Switec and X27.168 are names used by their makers.
  This library is not made or endorsed by the gauge's makers, 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\X27_Speedometer_Demo\X27_Speedometer_Demo.ino, select
Arduino Uno and use Sketch > Export Compiled Binary. Replace the simulation's
.hex with the exported HEX. The sketch needs 7,786 bytes of flash (24 % of the
UNO) and 295 bytes of RAM.

MODEL SCOPE AND LIMITS
Modelled: the two coils (resistance, inductance, the back-EMF of the turning
magnet), the rotor's torque from both coil currents, the 180 : 1 gear, inertia,
friction and the damping of the rotor's ringing, both end stops, lost steps,
the current each pin gives, a finger on the needle.
How it runs: the coils are part of the analog circuit (each a resistor-and-
inductor companion model with its back-EMF, solved by Proteus with the pins'
own resistance); between two analog points the rotor runs in 5 us steps. The
analog step shrinks to 100 us while the needle moves.
Not modelled: microstepping drivers (VID6606 and similar), gear play, the
needle's bounce at a stop in detail, the spread from part to part, noise.

VERSION
TEP X27.168 Speedometer Gauge library V1.0 (Oct 2026). Device X27168TEP
(TEPX27.LIB / TEPX27.DLL). Demo sketch X27_Speedometer_Demo V1.0. Demo board:
ARDUINO UNO V4.0 (TEP Arduino Library V4.0) with its built-in serial monitor.