ESP32-C6 ADC Comprehensive Testing Suite

Overview

The ADC comprehensive testing suite provides thorough validation of the EspAdc implementation on ESP32-C6 hardware. It includes 12 test categories covering hardware validation, initialization, channel configuration, calibration, one-shot and continuous modes, threshold monitoring, error handling, statistics, and performance characteristics.

Hardware Requirements

Target Hardware

• ESP32-C6 DevKit-M-1 (primary target)
• ESP32-C6 DevKitC-1 (also supported, just wifi antenna difference)
• USB-C cable for programming and power
• Computer with ESP-IDF v5.5+ installed

Required Components

• 10kΩ potentiometer (for threshold monitoring on GPIO0)
• Resistors: Two 10kΩ resistors for voltage references
• Jumper wires for connections
• Breadboard (recommended for clean connections)

Hardware Setup

The test suite exercises 3 ADC channels with specific voltage references:

Channel Configuration

• GPIO3 (ADC1_CH3): Voltage divider reference (~1.65V)
• GPIO0 (ADC1_CH0): Potentiometer center tap (0-3.3V variable)
• GPIO1 (ADC1_CH1): Ground reference (~0V)

Circuit Connections

```text ESP32-C6 Test Circuit:

3.3V Rail: | ├── [10kΩ] ──┬── [10kΩ] ── GND (Voltage Divider for GPIO3) │ │ │ └── GPIO3 (ADC1_CH3) (~1.65V reference) │ ├── [Potentiometer 10kΩ] │ ├── 3.3V (top terminal) │ ├── GPIO0 (center wiper, ADC1_CH0) (Variable 0-3.3V) │ └── GND (bottom terminal) │ └── GPIO1 (ADC1_CH1) ── [10kΩ] ── GND (~0V reference)

Expected Voltages:

• GPIO3: ~1650mV (1500-1800mV acceptable)
• GPIO0: 0-3300mV (variable via potentiometer)
• GPIO1: ~0mV (0-300mV acceptable) ```text

Test Suite Structure

The test suite includes 12 comprehensive test categories:

1. Hardware Validation Test

Function: test_hardware_validation()

• Validates physical hardware connections before other tests
• GPIO3: Expects ~1650mV (voltage divider validation)
• GPIO1: Expects ~0mV (ground connection validation)
• GPIO0: Variable voltage check (potentiometer functionality)
• Provides specific troubleshooting guidance for connection issues

2. ADC Initialization Test

Function: test_adc_initialization()

• Tests basic ADC unit initialization
• Verifies ESP32-C6 configuration (1 ADC unit, 7 channels)
• Validates channel availability checking
• Tests error handling for invalid channels

3. Channel Configuration Test

Function: test_adc_channel_configuration()

• Tests channel configuration with 12dB attenuation
• Validates channel enable/disable functionality
• Tests 12-bit width configuration
• Verifies configuration persistence

4. Basic Conversion Test

Function: test_adc_basic_conversion()

• Tests one-shot ADC readings (raw and voltage)
• Validates 12-bit ADC output range (0-4095)
• Tests both EspAdc and BaseAdc interface methods
• Verifies voltage readings within expected ranges

5. Calibration Test

Function: test_adc_calibration()

• Tests ADC calibration initialization
• Validates calibration availability for different attenuations
• Tests raw-to-voltage conversion using hardware calibration
• Handles ESP32-C6 specific calibration characteristics

6. Multiple Channels Test

Function: test_adc_multiple_channels()

• Tests simultaneous reading from all configured channels
• Hardware-specific validation per channel:
  • GPIO3: Expects 1500-1800mV (voltage divider validation)
  • GPIO1: Expects 0-300mV (ground reference validation)
  • GPIO0: Accepts 0-3300mV (potentiometer range validation)
• Tests bulk reading operations with real hardware verification

7. Averaging Test

Function: test_adc_averaging()

• Tests ADC averaging with different sample counts (1, 4, 8, 16)
• Validates noise reduction through averaging
• Tests timing between samples
• Verifies averaged values within expected bounds

8. Continuous Mode Test

Function: test_adc_continuous_mode()

• Tests continuous (DMA) mode operation with 1kHz sampling
• Validates callback-based data collection
• Tests ISR-safe callback implementation
• Measures continuous sampling performance over 2 seconds
• Verifies proper start/stop functionality

9. Monitor Threshold Test

Function: test_adc_monitor_thresholds()

• Interactive threshold testing using potentiometer on GPIO0
• Automatic threshold calculation based on baseline reading
• Real-time voltage monitoring with ESP-IDF buffer draining
• Interactive user guidance with step-by-step instructions
• Comprehensive validation:
  • Event counting (high/low threshold crossings)
  • ISR callback verification
  • Real-time voltage display updates

10. Error Handling Test

Function: test_adc_error_handling()

• Tests error handling for invalid operations
• Validates rejection of invalid channel numbers
• Tests null pointer handling
• Ensures disabled channel access rejection
• Validates configuration requirements

11. Statistics and Diagnostics Test

Function: test_adc_statistics()

• Tests ADC statistics collection
• Validates conversion timing measurements
• Tests diagnostic information gathering
• Tests statistics reset functionality
• Verifies performance metrics tracking

12. Performance Test

Function: test_adc_performance()

• Measures ADC conversion speed over 1000 conversions
• Tests high-frequency reading capabilities
• Validates timing characteristics (expects <1ms per conversion)
• Provides performance benchmarking data
• Measures execution time and calculates averages

Building and Running Tests

Prerequisites

1. ESP-IDF v5.5+ installed and configured
2. ESP32-C6 development board connected
3. Hardware test setup completed (potentiometer on GPIO0 required)
4. Voltage references connected to GPIO1 and GPIO3

Build Commands

```bash cd examples/esp32

Build ADC test

./scripts/build_app.sh adc_test Release

Flash and monitor

./scripts/flash_app.sh adc_test Release flash ./scripts/flash_app.sh monitor ```text

Expected Test Results

Successful Test Run

```text I (270) ADC_Test: ╔══════════════════════════════════════════════════════════════════════════════╗ I (292) ADC_Test: ║ ESP32-C6 ADC COMPREHENSIVE TEST SUITE ║ I (301) ADC_Test: ║ HardFOC Internal Interface ║ I (310) ADC_Test: ║ ║ I (319) ADC_Test: ║ Hardware Setup Required (ESP32-C6 DevKit-M-1): ║ I (328) ADC_Test: ║ - GPIO3 (ADC1_CH3): Connect to 3.3V via voltage divider (high reference) ║ I (337) ADC_Test: ║ - GPIO0 (ADC1_CH0): Connect to potentiometer center tap (variable 0-3.3V) ║ I (346) ADC_Test: ║ - GPIO1 (ADC1_CH1): Connect to ground via 10kΩ resistor (low reference) ║ I (356) ADC_Test: ║ ║ I (365) ADC_Test: ║ Monitor Test: Adjust potentiometer on GPIO0 during monitor test ║ I (374) ADC_Test: ╚══════════════════════════════════════════════════════════════════════════════╝

I (2664) ADC_Test: GPIO3 (HIGH): 1627 mV I (2667) ADC_Test: GPIO3: Hardware connection verified I (2672) ADC_Test: GPIO1 (LOW): 0 mV I (2676) ADC_Test: GPIO1: Hardware connection verified I (2680) ADC_Test: GPIO0 (POT): 1965 mV I (2684) ADC_Test: GPIO0: Potentiometer reading valid I (2689) ADC_Test: [SUCCESS] Hardware validation passed - all connections verified

…

I (12238) ADC_Test: 📈 0/10 sec | Voltage: 1328 mV (1.328V) | High events: 0 | Target: >1873 mV I (14238) ADC_Test: 📈 2/10 sec | Voltage: 2050 mV (2.050V) | High events: 947 | Target: >1873 mV I (14238) ADC_Test: 🎉 HIGH THRESHOLD TRIGGERED! Event #948 detected

…

I (33568) ADC_Test: Total: 12, Passed: 12, Failed: 0, Success: 100.00%, Time: 28902.67 ms I (33573) ADC_Test: [SUCCESS] ALL ADC TESTS PASSED! ```text

Monitor Threshold Test Details

The monitor test provides interactive guidance:

1. Baseline Setup: 5-second stabilization period using one-shot mode
2. Threshold Calculation: Automatic high/low threshold setting based on baseline
3. High Threshold Test: 10-second period to trigger high threshold
4. Low Threshold Test: 10-second period to trigger low threshold
5. Real-Time Display: Continuous voltage updates using ESP-IDF buffer draining

Troubleshooting

Hardware Connection Issues

GPIO3 Reading Incorrect

• Expected: ~1650mV (1500-1800mV range)
• Problem: Voltage divider not connected properly
• Solution: Verify 3.3V → 10kΩ → GPIO3 → 10kΩ → GND connection

GPIO1 Reading Too High

• Expected: ~0mV (0-300mV range)
• Problem: Not properly connected to ground
• Solution: Verify GPIO1 → 10kΩ → GND connection

GPIO0 Potentiometer Issues

• Expected: Variable 0-3300mV when turning potentiometer
• Problem: No variation or fixed reading
• Solution: Check 3-terminal connection: 3.3V → top, GND → bottom, GPIO0 → center

Test Failure Analysis

Monitor Test No Events

• Problem: Potentiometer not adjusted during test
• Solution: Actively turn potentiometer during 10-second monitoring periods
• Expected: Threshold events when crossing calculated thresholds

Performance Issues

• Problem: Slow conversions (>1ms per conversion)
• Solution: Check ESP-IDF configuration and hardware connections
• Expected: ~50µs per one-shot conversion

Calibration Failures

• Problem: Calibration not available
• Note: Some ESP32-C6 units may not have calibration data - this is normal
• Solution: Linear conversion is used as fallback

Test Configuration

ADC Configuration Used

• Attenuation: 12dB (full 3.3V range)
• Resolution: 12-bit (0-4095 counts)
• Sampling Frequency: 1kHz (continuous mode), 2kHz (monitor mode)
• Buffer Configuration: 64 samples per frame, 4 frames maximum

Expected Performance

• Conversion Speed: <1ms per one-shot conversion
• Continuous Mode: 1000+ samples/second sustained
• Accuracy: ±50mV typical with calibration
• Monitor Response: Real-time threshold detection

Architecture Notes

The test suite validates:

1. Hardware Abstraction: Tests both EspAdc and BaseAdc interfaces
2. ESP32-C6 Features: Single ADC unit, 7-channel configuration
3. ESP-IDF v5.5+ APIs: Latest ADC calibration and monitor APIs
4. Real-World Usage: Interactive hardware testing with potentiometer
5. Production Readiness: Complete error handling and diagnostics

Related Documentation

• EspAdc API Reference - Complete API documentation
• BaseAdc API Reference - Base class interface
• ESP32 API Overview - ESP32 implementation overview
• HardwareTypes Reference - Type definitions