G29_ShifterSniffer

A wireless gear shift sniffer and transmitter for Logitech G29 racing wheel simulation using ESP8266 and ESP-NOW protocol. This project interfaces directly with the G29 shifter hardware, reads analog gear position data, and transmits it wirelessly to display or receiver units.

Features

Hardware Interface: Direct analog reading from G29 shifter potentiometers
Wireless Communication: ESP-NOW protocol for low-latency gear data transmission
SPI Monitoring: Intercepts and decodes SPI communication from shifter
Gear Mapping: Intelligent mapping of analog values to gear positions (R, N, 1-6)
Reverse Detection: Special handling for reverse gear with button press detection
High Precision: 200Hz polling rate for responsive gear detection
Guaranteed Delivery: Retry mechanism until packet delivery is confirmed
PlatformIO Compatible: Built for embedded development with PlatformIO

Hardware Requirements

MCU: ESP8266 (NodeMCU v2 or compatible)
Shifter: Logitech G29 shifter with analog potentiometers
Power Supply: 5V power source for ESP8266
Receiver: ESP8266 device running G29_ShifterReceiver or G29_ShifterDisplay
Optional: External antenna for improved wireless range

Wiring Configuration

Component	ESP8266 GPIO	Description
Analog Input	GPIO A0	X-axis potentiometer reading
Control X	GPIO 13 (D7)	X-axis analog mux control
Control Y	GPIO 15 (D8)	Y-axis analog mux control
Status LED	GPIO 14 (D5)	Visual feedback indicator
Reverse Button	GPIO 4 (D2)	Reverse gear button detection
SPI CS	GPIO 5 (D1)	SPI chip select interrupt

Analog Multiplexer Setup

The shifter uses two potentiometers (X and Y axis) multiplexed to a single analog input:

X-axis: Left-right shifter movement
Y-axis: Forward-back shifter movement

SPI Interface

The shifter communicates via SPI bus:

CS Pin: Triggers interrupt on SPI communication
Reverse Detection: Monitors reverse button state via SPI data

Installation

Prerequisites

PlatformIO installed
ESP8266 development board support installed
Access to G29 shifter internal wiring

Setup Steps

Open Shifter: Disassemble the G29 shifter to access internal wiring
Identify Connections: Locate the analog potentiometer wires and SPI lines
Wire Connections: Connect according to the wiring table above

Update MAC Address: Modify receiver MAC address in src/main.cpp:

uint8_t broadcastAddress[] = {0xBC, 0xFF, 0x4D, 0x18, 0xBB, 0x31};

Build and Upload:
```
pio run --target upload
```
Monitor Serial Output:
```
pio device monitor
```

Usage

Basic Operation

Power on both the shifter sniffer and receiver devices
Move shifter - Analog values are read and mapped to gear positions
Monitor serial output to verify gear detection and transmission
Check LED feedback for transmission status

Gear Detection Algorithm

The shifter uses analog voltage levels to determine gear positions:

// Y-axis thresholds
int y_low = 180;   // Forward gears threshold
int y_high = 750;  // Reverse gears threshold

// X-axis thresholds
int x_low = 310;   // Left side threshold
int x_mid = 330;   // Center threshold
int x_high = 600;  // Right side threshold

Gear Mapping Logic

Reverse (-1): Y > 750, X position varies, Reverse button pressed
Neutral (0): Y between 180-750, X in center range
1st Gear (1): Y < 180, X on left side
2nd Gear (2): Y > 750, X on left side
3rd Gear (3): Y > 750, X in center
4th Gear (4): Y < 180, X in center
5th Gear (5): Y > 750, X on right side
6th Gear (6): Y < 180, X on right side

Serial Debug Output

Enable serial monitor to see:

Raw analog X and Y values
Calculated gear positions
SPI communication detection
Transmission status and confirmations

Dependencies

Arduino Framework: Core ESP8266 functionality
ESP8266WiFi: WiFi connectivity for ESP-NOW
espnow: Wireless peer-to-peer communication

Configuration

Pin Configuration

const int8_t analog_pin = A0;      // Analog input from mux
const int8_t control_x_pin = D7;   // X-axis mux control
const int8_t control_y_pin = D8;   // Y-axis mux control
const int8_t status_led_pin = D5;  // Status LED output
const int8_t reverse_pin = D2;     // Reverse button input
const int8_t CS = D1;              // SPI chip select interrupt

Timing Parameters

Polling Rate: 5ms (200Hz gear detection)
SPI Debounce: Interrupt-driven for precise timing
Transmission Retry: Immediate retry until delivery confirmed
Serial Monitor Speed: 115200 baud

Analog Thresholds

int y_low = 180;   // Forward gears threshold
int y_high = 750;  // Reverse gears threshold
int x_low = 310;   // Left side threshold
int x_mid = 330;   // Center threshold
int x_high = 600;  // Right side threshold

Troubleshooting

Common Issues

No gear detection:

Verify analog wiring connections (A0, D7, D8)
Check shifter potentiometer values in serial monitor
Adjust threshold values if shifter calibration differs
Test with known voltage sources on analog input

No wireless transmission:

Verify receiver MAC address is correct
Check ESP-NOW initialization in serial monitor
Ensure both devices are on same WiFi channel
Verify receiver is powered and running compatible code

SPI reverse detection not working:

Check CS pin interrupt wiring (D1)
Verify reverse button wiring (D2)
Monitor serial output for SPI activity
Test with direct button press detection

Inaccurate gear mapping:

Fine-tune threshold values for your specific shifter
Check analog readings for each gear position
Verify mux control pins are working correctly
Consider hardware calibration if values drift

Intermittent transmission:

Check power supply stability
Verify antenna connections
Consider adding external antenna for better range
Monitor serial output for delivery confirmations

Debug Information

Enable serial monitor at 115200 baud to see:

Raw analog X and Y values (for calibration)
Gear position calculations
SPI interrupt detection
ESP-NOW transmission status
Error messages from initialization

Hardware Calibration

Monitor Analog Values: Uncomment printXY(x,y) in loop()
Record Values: Note X,Y values for each gear position
Adjust Thresholds: Modify threshold constants to match your shifter
Test Calibration: Verify correct gear detection for all positions

Development

Project Structure

G29_ShifterSniffer/
├── src/
│   └── main.cpp          # Main application code
├── include/              # Header files (empty)
├── test/                 # Unit tests (placeholder)
└── platformio.ini        # PlatformIO configuration

Adding Features

Implement automatic calibration routine
Add support for different shifter models
Extend gear mapping for sequential shifters
Add clutch pedal support
Implement data filtering for stable readings

Testing

Use PlatformIO unit testing framework
Create mock shifter hardware for testing
Test with multiple receiver devices
Verify timing accuracy with oscilloscope

Hardware Interface

The shifter sniffer interfaces with:

Analog Multiplexer: Reads X and Y potentiometer values
SPI Bus: Monitors communication for reverse button state
Interrupt Handling: CS pin interrupt for precise SPI detection

Communication Protocol

Transmits gear data via ESP-NOW:

typedef struct struct_message {
    int16_t gear;  // Gear position: -1=Reverse, 0=Neutral, 1-6=Gears
} struct_message;

Data Flow

Read analog values from both potentiometers
Apply gear mapping algorithm
Detect reverse button via SPI monitoring
Send gear data via ESP-NOW with retry logic
Update status LED based on transmission success

Reverse Gear Detection

Reverse gear requires two conditions:

Position: Shifter in reverse gear slot
Button: Reverse button pressed (detected via SPI)

The SPI interrupt monitors the chip select line to detect when the reverse button is pressed, providing precise timing for reverse gear detection.

Contributing

Fork the repository
Create a feature branch
Make your changes
Add tests if applicable
Submit a pull request

License

This project is licensed under the terms specified in the License file.

Related Projects

G29_CustomSteeringWheel - Custom steering wheel with display
G29_Handbrake - Wireless handbrake controller
G29_ShifterDisplay - Gear shift indicator display
G29_ShifterReceiver - Wireless shifter receiver

Support

For issues and questions:

Check the troubleshooting section above
Verify shifter hardware connections and wiring
Review serial monitor output for analog values and gear detection
Ensure proper ESP-NOW initialization
Check threshold calibration for your specific shifter model

Hardware Notes

Shifter Disassembly: The G29 shifter requires partial disassembly to access:

Analog potentiometer connections
SPI communication lines
Reverse button detection circuit

Analog Calibration: Each shifter may have slightly different analog ranges. Use the serial monitor to calibrate threshold values for accurate gear detection.

SPI Monitoring: The SPI interface provides precise timing for reverse gear detection but requires careful interrupt handling.

Version History

v1.0.0 - Initial release with basic functionality
Direct hardware interface to G29 shifter
Analog gear position detection with custom mapping
SPI-based reverse gear detection
Wireless transmission with guaranteed delivery
High-precision 200Hz polling rate

Name		Name	Last commit message	Last commit date
.vscode		.vscode
include		include
lib		lib
src		src
test		test
.gitignore		.gitignore
License		License
README.md		README.md
platformio.ini		platformio.ini

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