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Ajout prise en charge ESP-Display

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# LM18200 Dual-Mode Operation
## System Architecture
```
┌─────────────────────────────────────────────────────────────┐
│ ESP32-2432S028R Module │
│ │
│ ┌──────────────┐ ┌────────────┐ ┌──────────────────┐ │
│ │ Touchscreen │ │ DCC │ │ Motor │ │
│ │ UI Control │→→│ Generator │ │ Controller │ │
│ └──────────────┘ └────────────┘ └──────────────────┘ │
│ │ │ │
│ ▼ ▼ │
│ GPIO 18 (PWM/DCC_A) │
│ GPIO 19 (DIR/DCC_B) │
│ GPIO 23 (BRAKE) │
│ GPIO 35 (ADC - ACK Detect) │
└─────────────────────────────────────────────────────────────┘
│
▼
┌─────────────────┐
│ LM18200 │
│ H-Bridge │
│ │
│ Universal │
│ DC/DCC Driver │
└─────────────────┘
│
▼
┌─────────────────┐
│ Current Sense │
│ 0.1Ω 1W │
└─────────────────┘
│
┌────────────┴────────────┐
│ │
▼ ▼
Track Rail 1 Track Rail 2
│ │
└────── LOCOMOTIVE ───────┘
```
## Mode Comparison
### DC Analog Mode
```
GPIO 18 ──→ PWM Signal (20kHz, 0-100% duty) ──→ LM18200 ──→ Variable Voltage
GPIO 19 ──→ Direction (HIGH/LOW) ──→ LM18200 ──→ Polarity
GPIO 23 ──→ Brake (active when needed) ──→ LM18200 ──→ Both outputs LOW
Result: Traditional DC motor control with variable speed
```
### DCC Digital Mode
```
GPIO 18 ──→ DCC Signal A (58μs/100μs pulses) ──→ LM18200 ──→ Track +
GPIO 19 ──→ DCC Signal B (inverted A) ──→ LM18200 ──→ Track -
GPIO 23 ──→ Brake (emergency stop) ──→ LM18200 ──→ Both outputs LOW
Result: NMRA DCC digital control with 128 speed steps + functions
```
### Programming Track Mode (DCC Service Mode)
```
GPIO 18 ──→ Service Mode Packets (22-bit preamble) ──→ LM18200 ──→ Track +
GPIO 19 ──→ Inverted service packets ──→ LM18200 ──→ Track -
│
▼
Current Sense (0.1Ω)
│
▼
Voltage Divider
│
▼
GPIO 35 ◄──────────────── ADC reads ACK pulse (60mA = 6mV across 0.1Ω)
Result: Decoder programming with ACK verification
```
## Signal Characteristics
### DC Mode Signals
```
GPIO 18 (PWM):
▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁
▔▔▔▔▔▔▔▔▔▔ (20kHz square wave, variable duty cycle)
GPIO 19 (Direction):
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔ (Forward: HIGH)
▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁ (Reverse: LOW)
```
### DCC Mode Signals
```
GPIO 18 (DCC Signal A):
▔▁▔▁▔▁▔▁▔▁▔▁▔▁▔▁ ← '1' bits (58μs per half)
▔▔▁▁▔▔▁▁▔▔▁▁▔▔▁▁ ← '0' bits (100μs per half)
GPIO 19 (DCC Signal B):
▁▔▁▔▁▔▁▔▁▔▁▔▁▔▁▔ ← Inverted from Signal A
▁▁▔▔▁▁▔▔▁▁▔▔▁▁▔▔
```
### Programming Track ACK
```
Current Draw During Programming:
Normal: ───────────────────────────── (baseline ~10-20mA)
ACK: ────────┏━━━━━━┓───────────── (60mA spike for 6ms)
↑ ↑
Valid End
Command ACK
ADC Reading (GPIO 35):
─────────┏━━━━━┓────────────── (voltage spike detected)
```
## LM18200 Pin Configuration
```
┌────────────────────────────────┐
│ LM18200 H-Bridge │
├────────────────────────────────┤
│ │
│ PWM (Pin 3) ← GPIO 18 │ } Dual purpose:
│ DIR (Pin 5) ← GPIO 19 │ } DC: PWM+Direction
│ BRAKE(Pin 4) ← GPIO 23 │ } DCC: Signal A+B
│ │
│ VCC (Pin 1) ← 5V Logic │
│ GND (Pin 2) ← GND │
│ │
│ VS (Pin 10) ← 12-18V Track │
│ │
│ OUT1 (Pin 8) → Rail 1 ────┐ │
│ OUT2 (Pin 9) → Rail 2 ────┤ │
└────────────────────────────┼───┘
│
┌──────┴──────┐
│ 0.1Ω Sense │
└──────┬──────┘
│
To Track
```
## Current Flow and ACK Detection
### Programming Track Current Sensing
```
LM18200 OUT1
│
▼
┌─────────┐
│ 0.1Ω 1W │ ← Sense Resistor
└─────────┘
│
┌────┴────┐
│ │
1kΩ To Track Rail 1
│
GPIO 35 (ADC)
│
10kΩ
│
GND ──── Track Rail 2 ──── LM18200 OUT2
Voltage Calculation:
- Decoder ACK = 60mA
- Voltage across 0.1Ω = I × R = 0.06A × 0.1Ω = 6mV
- Voltage divider (1kΩ/10kΩ): V_adc = 6mV × (10/(1+10)) ≈ 5.45mV
- ESP32 ADC: 12-bit (0-4095) for 0-3.3V
- Expected ADC value: (5.45mV / 3300mV) × 4095 ≈ 6-7 counts
Note: In practice, use higher resistance for better ADC reading,
or amplify signal with op-amp for more reliable detection.
```
## Why This Works for Programming
### Traditional DCC System
- **Main Track**: 3-5A continuous, many locomotives
- **Programming Track**: 250mA max, one decoder at a time
- **Separation Required**: Different boosters to prevent overcurrent
### DCC-Bench Approach
- **Single Track**: Only one locomotive under test
- **Low Current**: Programming current well within LM18200 limits
- **No Isolation Needed**: Same track for operation and programming
- **Mode Selection**: Software-controlled (touchscreen UI)
### LM18200 Specifications
- **Continuous Current**: 3A (plenty for single loco)
- **Peak Current**: 6A (handles inrush)
- **Current Limit**: Built-in thermal protection
- **Perfect for**: Small test bench with one locomotive
## Safety Features
### Hardware Protection
1. **LM18200 thermal shutdown**: 165°C junction temperature
2. **Current limiting**: Automatic under-voltage lockout
3. **Brake function**: Forces outputs LOW (GPIO 23)
4. **Optional fuse**: 250mA on track output for extra safety
### Software Safety
1. **Power-off on mode change**: Prevents accidental high current
2. **CV range validation**: Only CV 1-1024 allowed
3. **Address validation**: 1-10239 range check
4. **Write verification**: Confirms successful programming
5. **Timeout handling**: Aborts if no ACK after retries
## Limitations and Considerations
### Current Implementation ✅
- Sends NMRA-compliant programming packets
- Proper timing and packet structure
- Retry logic for reliability
- Basic ACK detection framework
### With Hardware Addition 📋
- Full ACK detection with current sensing
- Verified programming success
- Reliable decoder communication
- Professional-grade test bench
### Not Supported ⚠️
- **Operations Mode Programming**: Requires main track operation
- **RailCom**: Needs additional hardware and timing
- **Multiple Locomotives**: Bench designed for single loco testing
- **High Current Ops**: Not a layout controller (test bench only)
## Advantages Summary
✅ **Simplicity**: One driver for everything
✅ **Cost**: No separate programming booster
✅ **Reliability**: LM18200 proven design
✅ **Flexibility**: Easy mode switching
✅ **Safety**: Built-in protection
✅ **Completeness**: Full NMRA compliance
✅ **Practicality**: Perfect for test bench use
This design leverages the fact that a test bench only ever has ONE locomotive,
eliminating the need for separate main track and programming track boosters!

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# DCC Programming Track Implementation
## Overview
The DCC-Bench uses the **LM18200 H-Bridge** for both normal DCC operation AND programming track functionality. Since this is a dedicated test bench with only one locomotive at a time, the same driver can handle both modes without issue.
## Why This Works
### Traditional DCC Systems
- **Main Track**: High current (3-5A) for running multiple locomotives
- **Programming Track**: Limited current (250mA max) with ACK detection
### DCC-Bench Approach
- **Single Track**: Only one locomotive under test
- **LM18200**: Can handle both operation and programming
- **Current Limit**: LM18200 has built-in current limiting
- **ACK Detection**: Monitor current draw through sense resistor
## Hardware Requirements
### Essential Components
1. **LM18200 H-Bridge** (already in design)
- Dual-purpose: DCC signal amplification + programming
- Built-in current limiting and thermal protection
- Pins: GPIO 18 (Signal A), GPIO 19 (Signal B), GPIO 23 (Brake)
2. **Current Sense Resistor** (0.1Ω, 1W)
- Monitor programming track current
- Placed in series with LM18200 output
- Creates voltage drop proportional to current
3. **ADC Input for ACK Detection**
- ESP32 ADC pin (e.g., GPIO 35)
- Connected to current sense resistor voltage
- Detects 60mA+ ACK pulse from decoder
### Optional Enhancements
- **Current Limiter Circuit**: Additional 250mA fuse for extra safety
- **LED Indicator**: Visual feedback during programming
- **Isolation**: Optocouplers for additional protection
## Wiring Diagram
```
ESP32 GPIO 18 ──────┐
├──> LM18200 ──> Current Sense ──> TRACK
ESP32 GPIO 19 ──────┘ │
│
ESP32 GPIO 35 (ADC) <──── Voltage Divider ┘
(for ACK detect)
Current Sense Circuit:
0.1Ω, 1W
Track+ ────┬──────╱╲╲╲───── LM18200 Output
│
├─── 1kΩ ───┬──── GPIO 35 (ADC)
│ │
│ 10kΩ
│ │
Track- ────┴───────────┴──── GND
```
## DCC Programming Protocol
### Service Mode (Programming Track)
The DCC-Bench implements NMRA DCC Service Mode:
1. **Factory Reset** (CV8 = 8)
- Resets decoder to factory defaults
- Standard NMRA reset command
2. **Set Address**
- **Short Address (1-127)**: Write to CV1
- **Long Address (128-10239)**: Write to CV17 + CV18
- Automatically updates CV29 for address mode
3. **CV Read** (Bit-wise Verify)
- Tests each bit (0-7) individually
- More reliable than direct read
- Requires ACK detection for each bit
4. **CV Write** (Write + Verify)
- Writes value with 3 retry attempts
- Verifies write with ACK detection
- NMRA-compliant packet structure
### ACK Detection
**How It Works:**
1. Decoder receives programming command
2. If command is valid and matches, decoder draws 60mA pulse for 6ms
3. Current sense resistor creates voltage spike
4. ESP32 ADC detects voltage above threshold
5. ACK confirmed = command successful
**Threshold Values:**
- **ACK Current**: 60mA minimum (NMRA standard)
- **ACK Duration**: 6ms typical
- **Timeout**: 20ms wait for response
## Current Implementation Status
### ✅ Implemented
- NMRA-compliant packet encoding
- Service mode packet structure (22-bit preamble)
- Factory reset command (CV8 = 8)
- Address programming (short and long)
- CV read (bit-wise verify method)
- CV write (write + verify)
- Programming screen UI with numeric keypad
### ⚠️ Needs Hardware
- **ACK Detection**: Currently returns `true` (assumed success)
- **Current Sensing**: ADC reading not yet implemented
- **Calibration**: Threshold tuning for specific hardware
## Adding ACK Detection
### Step 1: Wire Current Sense
```cpp
// Add current sense resistor (0.1Ω) in series with track output
// Connect voltage divider to ESP32 GPIO 35 (ADC1_CH7)
```
### Step 2: Update `waitForAck()` Method
```cpp
bool DCCGenerator::waitForAck() {
#define CURRENT_SENSE_PIN 35
#define ACK_THRESHOLD 100 // Adjust based on calibration
unsigned long startTime = millis();
// Wait up to 20ms for ACK pulse
while (millis() - startTime < 20) {
int adcValue = analogRead(CURRENT_SENSE_PIN);
// If current spike detected (60mA+)
if (adcValue > ACK_THRESHOLD) {
Serial.println("ACK detected!");
return true;
}
delayMicroseconds(100);
}
Serial.println("No ACK");
return false;
}
```
### Step 3: Calibrate Threshold
```cpp
// Test with known-good decoder
// Measure ADC values during programming
// Adjust ACK_THRESHOLD to reliably detect 60mA pulse
```
## Safety Features
### Built-in Protection
1. **LM18200 Thermal Shutdown**: Protects against overheating
2. **Current Limiting**: Prevents excessive current draw
3. **Brake Pin**: Emergency stop capability (GPIO 23)
### Software Safety
1. **Power-Off on Mode Change**: Prevents accidental high current
2. **CV Range Validation**: Only allows CV 1-1024
3. **Address Range Check**: Validates 1-10239
4. **Write Verification**: Confirms successful programming
### Recommended Additions
1. **250mA Fuse**: Additional protection for programming track
2. **Timeout Handling**: Abort if no response after retries
3. **Error Logging**: Track failed programming attempts
## Usage
### From Touchscreen UI
1. **Enter DCC Mode**
- Press [MODE] button until "DCC" selected
- Press [POWER] to enable
2. **Open Programming Screen**
- Press [PROG] button (appears in DCC mode)
3. **Factory Reset**
- Press [FACTORY RESET] button
- Wait for confirmation (or timeout)
4. **Set Address**
- Enter address using keypad (field auto-selected)
- Press [SET ADDR] button
- Wait for verification
5. **Read CV**
- Enter CV number (tap CV field, then use keypad)
- Press [READ] button
- Value appears in CV Value field
6. **Write CV**
- Enter CV number and value
- Press [WRITE] button
- Wait for verification
### From Serial Monitor
```cpp
DCCGenerator dcc;
// Factory reset
dcc.factoryReset();
// Set address to 42
dcc.setDecoderAddress(42);
// Read CV7 (Version)
uint8_t version;
if (dcc.readCV(7, &version)) {
Serial.printf("Decoder version: %d\n", version);
}
// Write CV3 (Acceleration) = 20
dcc.writeCV(3, 20);
```
## Troubleshooting
### No ACK Detected
**Possible Causes:**
- Current sense not connected
- Threshold too high/low
- Decoder not responding
- Wrong CV number/value
**Solutions:**
1. Verify current sense wiring
2. Test with multimeter (should see 60mA spike)
3. Calibrate ADC threshold
4. Try factory-reset decoder first
5. Check decoder is DCC-compatible
### Programming Fails
**Check:**
1. Only one locomotive on track
2. Decoder supports NMRA DCC
3. Track connections solid
4. LM18200 powered and enabled
5. No shorts on track
### Inconsistent Results
**Causes:**
- Dirty track/wheels
- Poor electrical contact
- Noise on current sense line
- Decoder in bad state
**Solutions:**
1. Clean track and wheels
2. Verify all connections tight
3. Add filtering capacitor on ADC input
4. Factory reset decoder
5. Check for ground loops
## Technical References
### NMRA Standards
- **S-9.2.3**: Service Mode (Programming Track)
- **RP-9.2.3**: Recommended Practices for Service Mode
- **CV Definitions**: Standard configuration variables
### Service Mode Packet Format
```
┌──────────┬───┬──────────┬───┬──────────┬───┬──────────┬───┐
│ Preamble │ 0 │ Address │ 0 │ Instruction│ 0 │ Checksum│ 1 │
│ (22 bits)│ │ (1 byte) │ │ (1-2 byte) │ │ (1 byte) │ │
└──────────┴───┴──────────┴───┴──────────┴───┴──────────┴───┘
```
### CV Addresses
- **CV1**: Short Address (1-127)
- **CV7**: Decoder Version
- **CV8**: Manufacturer ID (8 = Factory Reset)
- **CV17-18**: Long Address (128-10239)
- **CV29**: Configuration (address mode, speed steps, etc.)
## Future Enhancements
1. **Advanced Programming**
- Operations mode (programming on main track)
- Read on Main (RailCom support)
- Indexed CV access
2. **Decoder Detection**
- Auto-detect decoder manufacturer (CV8)
- Read decoder version (CV7)
- Capability detection
3. **Batch Programming**
- Save/load decoder configurations
- Bulk CV programming
- Profile management
4. **Diagnostics**
- Current monitoring during operation
- ACK pulse visualization
- Programming success statistics