BHR Speed Controller

A motor speed controller firmware supporting multiple hardware platforms. Controls a 12V DC motor with PWM output and optional RPM feedback for PID control.

Build Variants

The project supports two build configurations:

1. ESP32 with Touch Display (bhrsc-ST7789-E)

• Full-featured version with TFT display and touchscreen interface
• Deep sleep power management
• Visual feedback and intuitive touch controls

2. Arduino Nano AVR (nano-avr)

• Minimal version with 3-button interface
• No display or touch interface
• Serial monitor for feedback
• Lower cost and smaller footprint

Hardware Requirements

ESP32 Variant (bhrsc-ST7789-E)

• CYD Board: ESP32-2432S028 (ESP32 with ST7789 240x320 TFT display and XPT2046 touchscreen)
• Motor: 12V DC motor
• Driver: MOSFET or motor driver connected to GPIO 18 (PID_OUTPUT)
• RPM Sensor (optional): Connected to GPIO 27 (RPM_INPUT)

Arduino Nano AVR Variant (nano-avr)

• Board: Arduino Nano (ATmega328P)
• Motor: 12V DC motor
• Driver: MOSFET or motor driver connected to Pin 9 (PWM_OUTPUT_PIN)
• RPM Sensor (optional): Connected to Pin 2 (RPM_INPUT)
• Buttons:
  • Pin 3: START/STOP button (with pull-up resistor)
  • Pin 4: SPEED UP button (with pull-up resistor)
  • Pin 5: SPEED DOWN button (with pull-up resistor)

Features

Control Modes

1. Fixed Power Mode: Maintains constant PWM duty cycle regardless of load

   • User sets target power percentage (0-100%)
   • Motor runs at fixed power output

2. PID Control Mode: Maintains target RPM using feedback control

   • Requires RPM sensor connection
   • Automatically adjusts power to maintain desired speed
   • Falls back to fixed power if RPM sensor not enabled

Configuration Options

• Target Power: 0-100% (adjustable in 5% increments)
• Target RPM: 0-5000 RPM (adjustable in 50 RPM increments)
• Soft Start: 5 seconds (default) - gradually ramps up power/speed
• Timeout: Configurable auto-shutoff after set duration
• PID Parameters: Kp=0.5, Ki=0.1, Kd=0.01 (adjustable in code)

User Interface

The touchscreen displays:

• Current Mode: Fixed Power or PID Control
• Motor State: STOPPED, STARTING, or RUNNING
• Current Power: Real-time power output percentage
• Current RPM: Live RPM reading (if sensor enabled)
• Target Power: Desired power level
• Target RPM: Desired speed (in PID mode)

Touch Controls (ESP32 Variant)

• START/STOP Button (Green/Red): Start or stop the motor
• Mode Button (Blue): Toggle between Fixed Power and PID modes
• Power +/- Buttons (Cyan): Adjust target power
• RPM +/- Buttons (Magenta): Adjust target RPM
• SLEEP Button (Orange): Enter deep sleep mode to save battery

Button Controls (Arduino Nano AVR Variant)

• Pin 3 (START/STOP): Toggle motor on/off
• Pin 4 (SPEED UP):
  • Single press: Increase target by 5% (Fixed Power) or 100 RPM (PID mode)
  • Hold: Auto-repeat every 200ms
• Pin 5 (SPEED DOWN):
  • Single press: Decrease target by 5% (Fixed Power) or 100 RPM (PID mode)
  • Hold: Auto-repeat every 200ms

Note: Buttons should be wired with pull-up resistors (internal pull-ups are enabled). Press = connect to GND.

Power Management

The device supports deep sleep mode for battery-powered operation:

• Deep Sleep: Tap the SLEEP button (top right) to enter low-power sleep mode
• Wake Up: Press the BOOT button (labeled BOOT on CYD) to wake the device
• Power Consumption:
  • Active: ~100-200mA (display on)
  • Deep Sleep: ~10-150μA (99.9% power savings)
• Motor Safety: Motor automatically stops before entering sleep mode

Pin Configuration

Configured in platformio.ini:

PID_OUTPUT = 18    # PWM output to motor driver (25kHz, 8-bit)
RPM_INPUT = 27     # RPM sensor input (falling edge trigger)

Display and touch pins are pre-configured for CYD hardware.

Building and Uploading

1. Install PlatformIO
2. Open project folder in VS Code with PlatformIO extension

Build ESP32 Variant

pio run -e bhrsc-ST7789-E
pio run -e bhrsc-ST7789-E --target upload

Build Arduino Nano AVR Variant

pio run -e nano-avr
pio run -e nano-avr --target upload

Monitor Serial Output

pio device monitor

Or use the PlatformIO toolbar buttons in VS Code to select the environment and upload.

Usage

1. Power On: Device initializes and displays UI
2. Set Mode: Tap "Mode" button to select Fixed Power or PID Control
3. Adjust Target:
   • Use Power +/- buttons to set target power
   • Use RPM +/- buttons to set target RPM (PID mode)
4. Start Motor: Tap green "START" button
5. Monitor: Watch real-time power and RPM readings
6. Stop Motor: Tap red "STOP" button

Soft Start

When motor starts, power gradually increases over the configured soft start period (default 5 seconds):

• Fixed Power Mode: Power ramps from 0% to target power
• PID Mode: Target RPM ramps from 0 to target RPM

This reduces mechanical stress and current spikes.

Timeout Feature

Configure automatic motor shutoff:

g_state.config.timeoutMinutes = 30;  // Auto-stop after 30 minutes

Set to 0 to disable timeout.

RPM Sensor

The firmware expects 1 pulse per revolution on the RPM_INPUT pin:

• Uses falling edge interrupt detection
• Calculates RPM every 100ms
• Assumes motor stopped if no pulses for 2 seconds
• Enable/disable: g_state.config.rpmSensorEnabled = true/false

PID Tuning

Default PID parameters in global_state.h:

cfg.pidKp = 0.5f;   // Proportional gain
cfg.pidKi = 0.1f;   // Integral gain
cfg.pidKd = 0.01f;  // Derivative gain

Adjust these values based on your motor characteristics:

• Increase Kp for faster response (may cause oscillation)
• Increase Ki to eliminate steady-state error
• Increase Kd to reduce overshoot

File Structure

include/
  ├── global_state.h       # State management and configuration
  ├── pid_controller.h     # PID controller interface
  ├── display.h            # Display and UI functions (ESP32 only)
  ├── touch.h              # Touch input handling (ESP32 only)
  ├── buttons.h            # Button input handling (Arduino Nano only)
  ├── power_management.h   # Deep sleep functions (ESP32 only)
  └── motor_control.h      # Motor PWM and RPM measurement

src/
  ├── main.cpp             # Main program logic (multi-platform)
  ├── pid_controller.cpp   # PID implementation
  ├── display.cpp          # TFT display rendering (ESP32 only)
  ├── touch.cpp            # Touch event processing (ESP32 only)
  ├── buttons.cpp          # Button event processing (Arduino Nano only)
  ├── power_management.cpp # Power management (ESP32 only)
  └── motor_control.cpp    # Motor control and RPM sensing (multi-platform)

Safety Notes

• Motor driver must handle 12V and appropriate current for your motor
• Ensure proper heat sinking for MOSFET/driver
• Use flyback diode across motor terminals
• Consider current limiting in driver circuit
• Test with low power settings first

Troubleshooting

Motor doesn't start:

• Check MOSFET/driver connection to GPIO 18
• Verify power supply to motor driver
• Check motor connections
• Monitor serial output for debug messages

RPM reading is 0:

• Verify RPM sensor connection to GPIO 27
• Check sensor is generating pulses (use oscilloscope)
• Ensure rpmSensorEnabled is true
• Verify sensor output is 3.3V compatible

Touch not responding:

• Calibrate touch by adjusting TS_MIN_X, TS_MAX_X, TS_MIN_Y, TS_MAX_Y in touch.cpp
• Check touchscreen connections
• Try different rotation setting

PID oscillation:

• Reduce Kp value
• Increase soft start time
• Adjust PID gains incrementally

License

Open source - modify as needed for your application.