ESP Hardware Abstraction Layer for Analog Conversion Peripherals

[!NOTE] This component is currently in beta. Its API, behavior, and compatibility may change at any time and without notice; backward compatibility is not guaranteed. Use caution when integrating into production systems.

Overview

The esp_hal_ana_conv component provides a Hardware Abstraction Layer for analog conversion related peripherals across all ESP-IDF supported targets. This HAL currently supports Analog-to-Digital Converter (ADC), Digital-to-Analog Converter (DAC), Temperature Sensor and other analog conversion related peripherals. The HAL enables analog signal acquisition, generation, monitoring, and temperature measurement capabilities.

Architecture

The analog conversion HAL is structured in two main sub-layers:

1. HAL Layer (Upper): Defines the operational steps and data structures required to control analog conversion peripherals (e.g., initialization, channel configuration, conversion control, DMA setup, sensor reading).

2. Low-Level Layer (Bottom): Serves as a translation layer between the HAL and the register files defined in the soc component, handling target-specific register configurations.

Supported Controllers

ADC Controllers

This HAL supports various ADC controller types depending on the ESP chip:

• RTC Controller: Single conversion mode for low-power applications, supports deep sleep operation
• ULP Controller: Ultra-low-power controller for ULP coprocessor control
• Digital Controller (DIG): Continuous conversion mode with DMA support, high-performance multi-channel scanning
• Arbiter Controller (ARB): Manages multiple controller access to ADC2 (ESP32-S2, ESP32-S3)
• PWDET Controller: Power detection controller for Wi-Fi power monitoring (ADC2 only)

DAC Controllers

This HAL supports various DAC controller types depending on the ESP chip:

• RTC Controller: Direct voltage output control
• DMA Controller: High-speed data output via I2S or SPI DMA

Temperature Sensor Controllers

This HAL supports temperature sensor functionality depending on the ESP chip:

• Temperature Sensor: On-chip temperature monitoring with automatic range management

ADC Features

Work Modes

• Oneshot Mode: Single conversion per trigger, suitable for polling-based applications
• Continuous Mode: Continuous conversion with DMA, supports high-speed multi-channel scanning
• Low-Power Mode: Ultra-low-power operation for battery-powered applications
• PWDET Mode: Power detection mode for Wi-Fi power monitoring

Conversion Capabilities

• Multi-Unit Support: Support for ADC1 and ADC2 (where available)
• Conversion Modes:
  • Single unit mode (ADC1 or ADC2 only)
  • Both units mode (ADC1 and ADC2 simultaneously)
  • Alternate unit mode (ADC1 and ADC2 alternately)
• Resolution Options: 9-bit, 10-bit, 11-bit, 12-bit, 13-bit (chip-dependent)
• Attenuation Options: 0dB, 2.5dB, 6dB, 12dB for different input voltage ranges
• Pattern Table: Configurable scan sequence with up to 16 patterns per unit

Signal Processing

• IIR Filtering: Digital IIR filters for noise reduction at high sampling rates
• Monitor Function: Hardware threshold monitoring with interrupt support
• Data Inversion: Optional data inversion for compatibility
• Calibration: Hardware and software calibration support for improved accuracy

Clock and Timing

• Flexible Clock Sources: APB clock, APLL, XTAL, RC_FAST (chip-dependent)
• Configurable Sampling Rate: Adjustable via clock division and trigger interval
• FSM Timing Control: Configurable wait times for reset, start, and standby phases

DAC Features

Output Capabilities

• Dual Channel Support: Two independent DAC channels (DAC_CHAN_0, DAC_CHAN_1)
• 8-bit Resolution: 256-level voltage output (0V to VDD3P3_RTC)
• Direct Voltage Output: Direct control of output voltage value

Cosine Wave Generator

• Frequency Control: Configurable frequency from 130Hz to several MHz
• Amplitude Control: Adjustable attenuation (0dB, 6dB, 12dB, 18dB)
• Phase Control: 0° or 180° phase shift support
• DC Offset: Configurable DC component for signal offset

Advanced Features

• DMA Output: High-speed data streaming via I2S, SPI or GDMA
• ADC-DAC Synchronization: Synchronized operation with ADC RTC controller
• Power Management: Independent power control per channel

Temperature Sensor Features

Measurement Capabilities

• Temperature Range: Typically -40°C to 125°C (chip-dependent)
• Automatic Range Management: Five configurable temperature ranges with optimized accuracy for each range
• Raw Value Reading: Direct access to raw temperature sensor values
• Degree Conversion: Automatic conversion from raw values to temperature in degrees Celsius

Range Management

• Multi-Range Support: Five temperature ranges with different offset and error characteristics
• Dynamic Range Switching: Automatic range adjustment based on measured temperature for optimal accuracy
• Range Tracking: HAL layer maintains range state to minimize unnecessary range switches

Advanced Features

• Sleep Retention: Register context retention during sleep modes (chip-dependent)
• Clock Source Selection: Flexible clock source configuration (XTAL, FOSC, etc., chip-dependent)
• ETM Support: Event Task Matrix integration for temperature monitoring events and tasks
• Wake-up Functionality: Temperature-based wake-up from sleep modes
• Power Control: Independent power and clock gating control

Usage

The HAL functions primarily serve ESP-IDF peripheral drivers such as esp_adc, esp_driver_dac, and esp_driver_tsens.

Advanced developers can use these interfaces directly when implementing custom drivers, with the understanding that API stability is not guaranteed.

Dependencies

• soc: Provides chip-specific register definitions
• hal: Core hardware abstraction utilities and macros