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Sensor Driver Interface

Sensor Driver Interface for ML and DSP applications.

It provides a simple interface to the application and relies on pre-configured sensors. Exposed is the sensor configuration and functions to enable/disable the sensor and to read out sensor data.

Sensor can operate in non-DMA or DMA mode with or without interrupt.

Sensor Driver API

The API is defined in sensor_drv.h. It features the following functions:

  • sensorGetId: Gets named sensor identifier which is used in other functions specifying a sensor. Pre-configured sensor are exposed through their names.
  • sensorGetConfig: Get configuration of a specified sensor.
    Sensor configuration is exported in the sensorConfig_t structure:
    • name: Sensor name.
    • dma_mode: DMA mode: 1=DMA, 0=non-DMA (FIFO).
    • sample_size: Sample size in bytes.
    • u.fifo structure in non-DMA mode (FIFO):
      • sample_interval: Sample interval in microseconds.
      • fifo_size: Sample FIFO size in bytes.
      • data_threshold: Data event threshold in number of samples.
        It specifies when the callback with event SENSOR_EVENT_DATA is generated. No event is generated when 0 is specified. The event is generated when the number of samples in the FIFO reaches the specified number of samples.
    • u.dma structure in DMA mode:
      • block_interval: Block interval in microseconds.
      • block_size: Block size in bytes for DMA mode.
      • block_num: Number of blocks for DMA mode.

      Note: Event SENSOR_EVENT_DATA is generated on every block captured.

  • sensorRegisterEvents: Registers an event callback function for the specified sensor with event mask.
  • sensorEnable: Enables a specified sensor (start capturing data with implicit data flush).
  • sensorDisable: Disables a specified sensor (stop capturing data).
  • sensorGetStatus Get status of specified sensor:
    • Active state: 1=active(enabled), 0=inactive(disabled)
    • Overflow flag (auto cleared)
  • sensorReadSamples: Read samples from specified sensor when in non-DMA mode.
  • sensorGetBlockData: Get block data from specified sensor when in DMA mode.

The following reference implementation is provided in sensor_drv.c. It features:

  • support for up to 8 sensors
  • common driver implementation with:
    • hardware configuration specified in sensor_config.h
    • hardware interface specified in sensor_drv_hw.h

      Note: requires hardware interface implementation (ex: sensor_drv_hw.c).

Sensor hardware interface implementation for using VSI (Virtual Streaming Interface) on Arm Virtual Hardware (AVH) is provided in directory VSI.