NxScope Library

NxScope provides real-time data logging by buffering samples into up to 255 virtual channels (vector, point, or text data) and streaming them through custom protocols and interfaces. It supports remote control via commands, timestamping, sample rate dividers, and critical non-buffered channels.

Use Cases

Real-time sensor data streaming and visualization.
Control system telemetry (PID tuning, state monitoring).
High-frequency signal capture (ADC).
Remote debugging and live variable tracking.

Configuration

CONFIG_LOGGING_NXSCOPE_INTF_SERIAL – Serial port interface
CONFIG_LOGGING_NXSCOPE_INTF_UDP – UDP interface (over Ethernet)
CONFIG_LOGGING_NXSCOPE_INTF_DUMMY – Dummy interface (for debug)
CONFIG_LOGGING_NXSCOPE_PROTO_SER – Default serial protocol (CRC-16)
CONFIG_LOGGING_NXSCOPE_DIVIDER – Sample rate divider support
CONFIG_LOGGING_NXSCOPE_ACKFRAMES – ACK frames for set requests
CONFIG_LOGGING_NXSCOPE_USERTYPES – Support for user-defined frames
CONFIG_LOGGING_NXSCOPE_CRICHANNELS – Support for non-buffered channels

Implementation

Serial interface: apps/logging/nxscope/nxscope_iser.c
UDP interface: apps/logging/nxscope/nxscope_iudp.c
Dummy interface: apps/logging/nxscope/nxscope_idummy.c
Default serial protocol: apps/logging/nxscope/nxscope_pser.c

Serial Protocol

The default serial protocol (nxscope_pser.c) uses a simple frame format with a header, data payload, and a CRC-16 footer.

Frame Format

SOF (1B)	Len (2B)	ID (1B)	Data (nB)	CRC-16 (2B)
`0x55`	u16 (LE)	u8	…	u16 (BE)

SOF: Start of Frame, always 0x55.
Len: Total frame length (including header and footer) in little-endian.
ID: Frame type identifier (see enum nxscope_hdr_id_e).
Data: Variable length data payload.
CRC-16: CRC-16-XMODEM (polynomial 0x1021) of the header and data.

Frame Types

The following frame types are defined in enum nxscope_hdr_id_e:

Type	ID	Description
`NXSCOPE_HDRID_STREAM`	1	Real-time stream data
`NXSCOPE_HDRID_CMNINFO`	2	Get common info (chmax, flags, padding)
`NXSCOPE_HDRID_CHINFO`	3	Get channel info (name, type, etc.)
`NXSCOPE_HDRID_ACK`	4	ACK/NACK response for set requests
`NXSCOPE_HDRID_START`	5	Start or stop the data stream
`NXSCOPE_HDRID_ENABLE`	6	Enable or disable specific channels
`NXSCOPE_HDRID_DIV`	7	Set samples divider for channels
`NXSCOPE_HDRID_USER`	8	User defined frames

Examples

The following applications in NuttX demonstrate the use of the NxScope library:

nxscope NxScope library example - Basic streaming example.
foc Field Oriented Control user-space library - Real-time FOC (Field Oriented Control) telemetry.
adcscope NxScope ADC data stream - ADC data visualization.
sensorscope NxScope sensor data stream - Sensor data streaming.

Supported Boards

Several board configurations in NuttX use the NxScope library:

nrf52832-dk:nxscope_rtt: Uses Segger RTT as the transport interface. This allows for high-speed data streaming without using a physical UART or USB cable (requires a J-Link debugger).
nrf52832-dk:nxscope_uart: Uses a physical UART interface with a high baud rate (1Mbps) for data streaming.
stm32f4discovery:nxscope_cdcacm: Uses USB CDC/ACM for the transport interface, providing a standard serial connection over USB.
qemu-intel64:jumbo: Uses the UDP interface for high-speed data streaming over an emulated Ethernet connection.
thingy53:sensors_cpuapp: Uses USB CDC/ACM with the sensorscope application to stream data from on-board sensors.
sim:nxscope: A configuration for the NuttX simulator that allows for easy testing and development of NxScope-related features on a host PC.
nucleo-c071rb:adcscope: Uses UART and ST-LINK VCOM with the adcscope application to stream data from ADC channels.

External Tools

Nxslib - Python client library.
Nxscli - Core command-line interface.
Nxscli-mpl - Matplotlib extension for nxscli.
Nxscli-pqg - PyQtGraph extension for nxscli.

Nxscli Quick Start

The Nxscli is a Python tool used to interface with NxScope-enabled devices. It uses a plugin-based architecture to capture, store, and visualize data.

Note

This is a quick command reference only. For a detailed description of all supported features, plugins, and configuration options, please visit the official repositories.

Note

A graphical user interface (GUI) for nxscli is currently under development and will be available soon.

Installation:

# Core tool
pip install nxscli

# Matplotlib extension (optional)
pip install nxscli-mpl

# PyQtGraph extension (optional)
pip install nxscli-pqg

Interface selection:

Select the interface to connect to your device:

# Serial port
nxscli serial <serial-port> ...

# Segger RTT
nxscli rtt <rtt-target> <rtt-buffer-index> <rtt-buffer-size>...

# UDP (Ethernet)
nxscli udp <target-ip> <target-port> ...

# Simulated/Dummy interface
nxscli dummy ...

Device information:

To display information about the connected NxScope device and its available channels:
```
# Serial interface
nxscli serial /dev/ttyACM0 pdevinfo
```

Data capture:

Configure channels and capture samples:

# Print samples from channels 0 and 1 via serial
nxscli serial /dev/ttyACM0 chan 0,1 pprinter

Visualization:

NxScope supports live visualization using Matplotlib or PyQtGraph:

# Live plot from serial using Matplotlib
nxscli serial /dev/ttyACM0 chan 0,1 m_live

# Live plot from serial using PyQtGraph
nxscli serial /dev/ttyACM0 chan 0,1 q_live

Data streaming:

To stream data over UDP (e.g., to PlotJuggler):
```
nxscli serial /dev/ttyACM0 chan 0,1 pudp 0
```