StarTrac Walk Intervals

Overview

The treadmill has its own control board with physical + / − / start / stop buttons. Rather than reverse-engineering or replacing that board, this firmware sits alongside it: four relay outputs press those same buttons on the controller's behalf, so the stock treadmill logic and safety behavior are untouched. An external start/stop button pair and a small control panel (wait, extreme-mode) let the user drive full workouts hands-off.

Two independent finite-state machines run in the main loop, sampled every 10 ms: treadmillProcessing owns the workout itself — idle, ramp-up, steady walk, and alternating high/rest HIIT intervals — while fakeStepsProcessing drives a vibration motor to simulate footfalls for a pedometer strapped to the deck, throttled to the belt's real pace and automatically silenced during high-intensity intervals so step counts stay believable.

A TM1637 4-digit display shows either the interval countdown or the day's simulated step count, and a second MCU pinned to a SoftwareSerial line streams every commanded speed change out as plain-text telemetry for external logging.

Signal architecture

The controller is the only piece of "smart" hardware in the loop — everything downstream of it is either a dumb relay contact or a passive display.

Pin reference

All pins are configured in setup(). Two logic conventions coexist: the external start/stop pair is plain INPUT (board-level pull assumed), while wait and extreme-mode buttons use INPUT_PULLUP and read active-low.

State machines

Two state machines run every loop pass. Debounce sub-states are shown under each diagram.

Function reference

Tuning constants

All user-configurable parameters defined at the top of the sketch. Adjust these for your treadmill's responsiveness and workout profile.

int on_time = 120;   // Button press hold
int off_time = 190;  // Button release

#define SLOW_STEP_TICKS 88
#define FAST_STEP_TICKS 53

const int CONSTANT_SPEEDS_ARRAY[5] = { 25, 32, 40, 80, 100 };
// Mapped to: 2.5, 3.2, 4.0, 8.0, 10.0 km/h

const int HIIT_HIGH_SPEEDS_ARRAY[8] = { 54, 80, 90, 100, 110, 120, 130, 140 };
// Mapped to: 5.4, 8.0, 9.0, 10.0, 11.0, 12.0, 13.0, 14.0 km/h

const int HIIT_high_interval_array[10] =
  { 60, 30, 150, 240, 300, 360, 420, 480, 540, 600 };
const int HIIT_rest_interval_array[4] =
  { 60, 64, 120, 180 };
// Extreme-mode button cycles through these presets

Auxiliary modules

Cooling fan control (ESP-NOW wireless)

Optional wireless control for a remote cooling fan via ESP8266-based ESP-NOW protocol:

• Basic_Master: Monitors the cooling-fan trigger pin, sends state over ESP-NOW
• slave_fan: Receives signal, drives physical fan relay

No WiFi router needed — pure point-to-point RF. Useful if the fan is mounted remotely or isolation is required between circuits.

Motor tuning bench sketch

watch_linear_motor/ contains a standalone sketch for tuning the fake-step vibration-motor timing in isolation. Later folded into fakeStepsProcessing() above.

Revision history

Complete firmware snapshots kept in old firmware/ directory — useful for diffing behavior or tuning speed tables across revisions.

Notes & known quirks