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# Architecture Source: [https://docs.qualcomm.com/doc/80-70015-7/topic/architecture.html](https://docs.qualcomm.com/doc/80-70015-7/topic/architecture.html) Note: - To continue reading about the APIs or set up sensor information, proceed directly to [Interfaces](https://docs.qualcomm.com/bundle/publicresource/topics/80-70015-7/qsh_api_reference.html). - Source code of the low-power processor (aDSP), including the QSH framework, is available only to licensed users with authorized access. To upgrade your access, go to: [www.qualcomm.com/support/working-with-qualcomm](https://www.qualcomm.com/support/working-with-qualcomm). QSH, which is synonymous with the Qualcomm® Snapdragon™ sensor core (SSC), offers a unified event-driven framework for drivers and algorithms. QSH supports the same set of APIs for both the hardware-based and software-based sensors. Additionally, QSH supports asynchronous bus transfer and is easily extendable for new or custom driver features. QSH consists of various components that include the QSH client APIs, sensor APIs, a core framework, pre-implemented platform sensors, vendor-implemented sensors, and the test modules. It serves external clients and provides a simple interface to access the sensor data. The following table describes the terms used in the QSH framework: Table : QSH terminology | **Item** | **Description** | | --- | --- | | Sensor |

Produces a single type of data; for example, accelerometer,
gyroscope, timer, interrupt, and rotation vector

Handles asynchronous data

Publishes mandatory and custom attributes, and manages its
instances

| | Sensor instance |

Runs at a specific configuration, publishes output data
events, and can be created per client request or shared among
multiple requests

Physical sensors usually share a single instance

| | Sensor unique identifier (SUID) | A unique 128‑bit ID for each sensor | | Service | A module that provides a synchronous interface for common
utilities | | Data stream | A unique connection between a client and data source | | Request | A configuration message that a client sends to a sensor (see
`sns_request.h` file) | | Event | Asynchronous output data message that a sensor instance generates
(see `sns_sensor_event.h` file) | | Nanopb | A small code-size protocol buffer implemented in ANSI C | The following figure shows the components of QSH architecture: Figure : QSH architecture components - **Application processor software modules** - **Client application**: It contains the *application main()* or *entry function* that interacts with the QSH client APIs on the application processor side. - **QSH client APIs**: It offers high-level APIs to access services offered by the QSH. It simplifies application development by abstracting system complexities and focusing on the application logic. For more information, see [Interfaces](https://docs.qualcomm.com/bundle/publicresource/topics/80-70015-7/qsh_api_reference.html). - **Low-power processor software modules** - **Client manager**: The client manager is in-charge of all communications of the low-power processor with the application processor. It is responsible for the following: Table : Client manager functions | Function | Description | | --- | --- | | Translate incoming requests | The client manager takes incoming requests and
translates them into a format that the QSH can
understand. | | Translate outgoing indications | The client manager receives event messages from the
QSH and translates these event messages into outgoing
indications in a format that is understandable outside
the QSH. | | Guarantees batching options | If a client specifies certain batching
(store/accumulate locally) options, then the client
manager ensures that the batching options are met. This
means it checks that the data is grouped and sent in the
way that the client has specified. | - **Service manager**: QSH offers synchronous services through its service manager. The sensor and sensor instance APIs use a callback to connect to this service manager. The `adsp_proc/qsh_platform/inc/sns_service.h` file lists the services available in the QSH, also referred as QSH services. The following table describes the key QSH services that are essential for device drivers. Table : QSH services | QSH service | Description | | --- | --- | | Stream service |

Enables creating and removing a data stream with
a sensor.

See the
adsp_proc/qsh_platform/inc/sns_data_stream.h
file for data stream API to send requests and
receive events over the data streams.

| | Attribute service |

Allows a sensor to publish sensor attributes or
capabilities.

All standard attribute IDs and expected value
type are defined in the
sns_std_sensor.proto file.

All attribute values must be in the
nanopb-encoded format.

For more information on the API, see the
adsp_proc/qsh_platform/inc/services/sns_attribute_service.h
file.

| | Diagnostic service |

Provides debug message and data log packet
services, and defines standard log packet
IDs.

For more information on the API, see the
adsp_proc/qsh_platform/inc/services/sns_diag_service.h
file.

| | Event service |

Enables to publish output events from source
sensor instances.

For more information on the API, see the
adsp_proc/qsh_platform/inc/services/sns_event_service.h
file.

| | Power rail service |

Available to the physical sensors to register
and vote for the power rails (ON/OFF).

For more information on the API, see the
adsp_proc/qsh_platform/inc/services/sns_pwr_rail_service.h
file.

| | Synchronous COM port (SCP) service |

Available to the physical sensors to
register/deregister the COM port and perform
synchronous transfers over the COM port.

For more information on the API, see the
adsp_proc/qsh_platform/inc/services/sns_sync_com_port_service.h
file.

| | GPIO service |

Available to the physical sensors to read/write
the GPIO value.

Effectively abstracts a low-level CoreBSP layer
for controlling the GPIOs.

For more information on the API, see the
adsp_proc/qsh_platform/inc/services/sns_gpio_service.h
file.

| | Island service |

Available to the physical sensors to request for
island exit.

When an application must access DDR or nonisland
resources, the application code can use the island
service.

For more information on the API, see the
adsp_proc/qsh_platform/inc/services/sns_island_service.h
file.

| | File system service |

Available to the physical sensors for the file
service management.

The abstract file system is a part of an
application processor stack and can be available
for local access from a low-power processor.

For more information on the API, see the
adsp_proc/qsh_platform/inc/services/sns_file_service.h
file.

| - **Platform sensor**: QSH provides some built-in sensors for platform or hardware-specific abstraction that other sensors and sensor instances can use. The following table describes the platform sensors: Table : Platform sensors | Platform sensor | Description | | --- | --- | | Registry sensor |

The registry sensor in the QSH provides an
interface for sensors to access registry data from
persistent memory. It allows sensors to create a
data stream, send requests, receive data events,
subscribe to updates, and remove unnecessary data
streams.

For more information on the registry sensor, see
Configure in
Qualcomm Linux
Sensors Guide - Addendum.
Note: Qualcomm Linux
Sensors Guide - Addendum is available to
licensed developers with authorized
access.

The registry sensor API is documented in the
adsp_proc/qsh_api/pb/sns_registry.proto
file.

| | Timer sensor |

The timer sensor in the QSH offers an interface
to initiate periodic or one-shot timers. Sensors
that require timers must create a data stream,
send requests, and read delivered data
events.

The timer sensor API is documented in the
adsp_proc/qsh_platform/api/public_sns/sns_timer.proto
file.

| | Interrupt sensor |

The interrupt sensor in the QSH offers an
interface to register interrupts. Sensors that
require interrupts must create a data stream, send
requests, and read delivered data events.

The interrupt sensor API is documented in the
adsp_proc/qsh_platform/api/public_sns/sns_interrupt.proto
file.

| | Asynchronous COM port (ASCP) sensor |

The ASCP sensor in the QSH offers an interface
for asynchronous read/write operations over a
communication port.

Sensors that require this feature must create a
data stream, send requests, and read delivered
data events.

The ASCP sensor API is documented in the
adsp_proc/qsh_platform/api/public_sns/sns_async_com_port.proto
file.

Note: The ASCP sensor is typically used by the physical
sensor drivers to read large FIFO. | | SUID lookup sensor |

The SUID lookup sensor in the QSH provides an
API to obtain the SUID of dependent sensors. Its
own SUID is available via the
sns_get_suid_lookup() function in
the sns_sensor_util.h file.

The SUID lookup sensor API is documented in the
adsp_proc/qsh_api/pb/sns_suid.proto
file.

| | Test sensor |

The test sensor is used to customize and run
sensor-specific use cases.

The test sensor is available in the
adsp_proc/qsh_platform/sensors/test
directory.

| - **QSH utilities**: QSH provides several helper utilities for sensors and sensor instances. All the utilities are available in the `adsp_proc/qsh_platform/inc/utils` directory. The following table describes the key utilities: Table : QSH utilities | QSH utility | Description | | --- | --- | | Nanopb encode/decode |

Provides common encode/decode helper functions for all
the sensors. For example, encode/decode
sns_request messages, encode and
publish/decode data events.

Asynchronous COM port nanopb utilities are available for
physical sensor drivers.

| | Sensor utils |

Provides common functionality, such as finding a sensor
instance and getting the SUID of a SUID lookup
sensor.

| | Attribute utils |

Provides helper function that encodes and publishes a
sensor attribute.

| | Memory utils |

Provides helper functions for efficient memory
management and allocation.

| | Math utils |

Offers a collection of mathematical functions
and operations such as matrix, FFT, and IIR
filter.

| | Printf utils |

Includes helper functions to format and print
data.

| ## Communication among sensors Source: [https://docs.qualcomm.com/doc/80-70015-7/topic/architecture.html](https://docs.qualcomm.com/doc/80-70015-7/topic/architecture.html) Every algorithm and sensor driver within the QSH framework is referred to as a sensor with the standard QSH APIs. Information exchange across these sensors is necessary for any real use case. All communication to, from, and among the sensors is performed through the request and event messages over data streams. The message payloads are defined in the protocol buffer format, using the nanopb generator, encoder, and decoder. The message payload length, message ID, and timestamp (for events) are communicated within metadata managed by the QSH framework. The following figure shows communication between data client and data source, using the data stream: Figure : Sensor communication between client and source Request messages are sent to enable, disable, and/or reconfigure a sensor. Request messages are always addressed to a specific SUID. After the target sensor receives the request message, it sends the request to the sensor instance for proper handling. Sensor instances send event messages asynchronously to their registered clients, which may be other sensors or sensor instances. ### Sensor and sensor instances - Sensors are producers, consumers, or a combination of producers and consumers of asynchronous data. - Each sensor can have one or more sensor instances. - Each sensor instance operates with a specific configuration. - Any request to a sensor for data results in the creation of a sensor instance or sharing of an existing sensor instance. - Sensor instances are created on-demand, as determined by the sensor. - Sensors fully manage the lifecycle and configuration of their corresponding instances and are responsible for sending configuration updates and initial state events to their clients. - Vendors must serve all client requests with a minimal number of sensor instances. - A stream of data generated by a sensor instance is sent to all the active clients. - Multiple sensors can share and configure a single sensor instance – this mode of operation is typical to a combo driver for hardware sensors. Here, the sensors represent the supported data types, and the sensor instance is the sole module that communicates and configures the hardware. ## Nanopb protocol buffer in QSH Source: [https://docs.qualcomm.com/doc/80-70015-7/topic/architecture.html](https://docs.qualcomm.com/doc/80-70015-7/topic/architecture.html) The QSH uses nanopb protocol buffer for: - All the request and event messages exchanged between the sensors. - A sensor or sensor instance must encode the payload (if present) for all requests it sends to its dependants. - A sensor or sensor instance must decode the payload (if present) for all requests it receives. - A sensor or sensor instance must encode the payload (if present) for all events it publishes. - A sensor or sensor instance must decode the payload (if present) for all events it receives from its dependants. Note: Some requests or events do not have a message body. In this case, decoding or encoding the payload is not expected. Process these messages based on their message ID. - Representing the attribute data - All attribute values are in the nanopb-encoded format - Diagnostic log packet payload - All payloads in the diagnostic log packets are in the nanopb-encoded format Note: For more information on Google protocol buffers and nanopb respectively, see [Protocol-buffers](https://developers.google.com/protocol-buffers/) and [nanopb](https://jpa.kapsi.fi/nanopb/). ## Sensor API messages Source: [https://docs.qualcomm.com/doc/80-70015-7/topic/architecture.html](https://docs.qualcomm.com/doc/80-70015-7/topic/architecture.html) The following files refer to the API messages, which contain message definitions, and are used for communication between sensors: - The `.proto` files contain protocol buffer message definitions and documentation to communicate between sensors. - The following table lists the standard message defined in the `/build-qcom-wayland/workspace/sources/sensinghub/sensing-hub/apis/proto/sns_std_*.proto` file: Table : Standard proto files | File | Description | | --- | --- | | `sns_std.proto` | This file includes standard definitions, such as:

A message ID

Request message

Batching specification

An attribute request and event

An error event

| | `sns_std_sensor.proto` | This file includes definitions, such as:

Message IDs for request and event APIs of standard
sensors

Streaming and event messages

Sensor sample status types

Standard attribute IDs

Common attribute types

A physical sensor configuration event message

| | `sns_std_type.proto` | This file includes common API-type definitions, such as:

SUID messages

Attribute events and value messages

Common error types

| | `sns_std_event_gated_sensor.proto` | This file includes the API for event gated sensors,
encompassing the configuration message ID and API
documentation. | - Physical sensor-specific API definitions and documentation are present in the sensor-specific `.proto` files. For example, `sns_accel.proto`, `sns_proximity.proto` and `sns_motion_detect.proto`. - Platform sensor API definitions and documentation are present in the `adsp_proc/qsh_platform/api/` directory. For example, `sns_timer.proto`, `sns_interrupt.proto`, and `sns_async_com_port.proto`. - Framework-related APIs for SUID, registry, and diagnostics are defined in the following proto files: - `sns_suid.proto` - `sns_registry.proto` - `sns_diag.proto` Last Published: Oct 14, 2024 [Previous Topic Features](https://docs.qualcomm.com/bundle/publicresource/80-70015-7/topics/supported_features.md) [Next Topic Interfaces](https://docs.qualcomm.com/bundle/publicresource/80-70015-7/topics/qsh_api_reference.md)