- Note
- SW Release Applicability: This sample is available in both NVIDIA DriveWorks and NVIDIA DRIVE Software releases.
The IMU Logger sample works with any serial port (UART) based IMU sensor or with the Xsens IMU device connected over USB. The logger requires the IMU sensor connected over serial port to deliver messages in NMEA format, while the Xsens device can run in proprietary mode.
Windows device driver information for Xsens USB-serial converter Xsens USB Serial converter links a serial device to a computer through the USB port. It is good for use on a PDA, digital camera, modem or ISDN terminal with a serial port. It supports high speed and is also ideal for connecting POS Peripherals.
The Xsens MTi driver uses Public Xsens Device API for scanning, connecting, packet parsing and log file handling. The implemention of this driver is done in C/C, so you can build and run it on a different platforms. Now the device needs a driver to take ownership of hardware which the USB pipe talks to. Until you put the module in for the hardware via CONFIGUSBSERIALXSENSMT (and perhaps other dependenciesthe config editor, e.g., “make nconfig”, would figure that out though) no driver exists to take ownership.
Interfacing with sensors
Serial
Consumer grade off-the-shelve IMU sensors are usually connected over USB and implement a serial-to-USB connection with the help of FTDI devices. The Xsens IMU device can be connected through a serial-to-USB connection.
On Linux, these sensors can then be reached over the /dev/ttyUSB or /dev/ttyACM devices. Before trying out the sample, ensure the user has access to the serial device. You can do so by trying to read from the device e.g. with cat /dev/ttyACMx, and if permission is denied, add the current user to the dialout group and then log out/in again:
On QNX, prior to accessing the device, launch the dev-serusb driver as follows:
The serial devices can the be reached over the /dev/serusb devices.
Xsens USB
The Xsens IMU device can also be connected directly over USB, but is only supported on Linux.
The sample requires the driver and name of the device of the IMU sensor.
The IMU Logger sample, sample_imu_logger, accepts the following parameters:
Where:
- Note
- For a full list of key/value pairs that can be passed to –params see Sensor Enumeration Sample.
Examples
NMEA format
For serial devices transmitting messages in NMEA format, use the imu.uart driver. For example:
Per default, if no baud parameter has been provided imu.uart driver assumes a baudrate of 9600. In order to change the baudrate provide baud argument as:
On QNX, the baudrate is set when starting devc-serusb. The baud parameter will be ignored.
Xsens proprietary format
The sample supports reading IMU packets from a Xsens device through the imu.xsens driver. To run the sample using Xsens over USB device use:
Where device=0 parameter sets the index of the Xsens device (usually 0 if only one device is installed) and frequency=100 sets the frequency in [Hz] this device should operate with.
To run the sample using Xsens over serial use:
Please note that even if the Xsens device is a shared device, like Xsens MTi-G-700, capable of delivering GPS and IMU packets, only the IMU packets will be parsed by the imu.xsens driver.
- Note
- If the device is connected to Xavier UART you need also specify –stop-bits=1
For every valid IMU message that the sample receives, it prints to the console data such as:
Where the first number indicates the timestamp of the received IMU message in microseconds and the rest of the line indicates the IMU information of the sensor.
For more details see IMU.
Newbie question involving direct hardware access:I am trying to access a sensor throught a USB-to-RS232 connector. The Sensor is a Xsens MTI.
I have some code to control the sensor, but so far I am unable to access it at all. /dev/ttyUSB0-4 did not exist, so after some searching I created them with mknod /dev/ttyUSB0 c 188 0, mknod /dev/ttyUSB1 c 188 1 ...
cat /dev/ttyUSB0 reports 'no such device' so I am obviously missing something.
/var/log/messages reports the sensor as 'kernel: usb 5-1: new full speed USB device using address 9' but nothing afterwards.There is supposedly a specialized driver included with kernel 2.6.14, which might help somehow, but I am unsure whether to attempt to update it manually, since I have not done that before either.
Xsens USB Devices Driver
