XDL120 | User Manual
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Data subj ect to change without notice
Bosch Connected Devi ces and Sol utions
2
Feature details
2.1
Accurate logging of sensor samples with timestamps
The XDL120 allows logging with high data rates for all on board sensors except the acoustic noise sensor without loss of
data, when individual sensors are configured. Data is homogeneously timestamped with millisecond resolution based on
the FreeRTOS system time. Table 1 provides a quick overview on the maximum sample rates per sensor. Please be aware
that those rates only apply if a single sensor is configured at a time for logging. For multiple sensors, the data rate for the
single sensors must be reduced.
The value described in the table refer to maximum values achieved in ideal conditions. In real applications, some data
might be lost e.g. due to noise on the sensor bus induced by increased temperature, or other factors. In our tests, the data
loss exhibited under real life testing conditions were typically in range of <0.5% of the maximum values setting.
If data from more than one sensor needs to be logged, it is recommended to reduce the data rate for the individual sensors
to minimize data loss. The file XDL120_tolerance_calculation.xls delivered with the XDL120 can help estimate typical data
loss when logging several sensors at once.
Table 1: Maximum raw data output of XDK sensors
Sensor
Data rate
BMI 160 – Gyroscope part
3200 Hz
BMI 160 – Acceleration part
1600 Hz
BMM150 – Magnetic field
30 Hz
BMA280 – Acceleration
1000 Hz (corresponds to bandwidth 500 Hz)
BME280 – Temperature, Humidity, Pressure
25 Hz
BMG160 – Gyroscope
1000 Hz (corresponds to bandwidth 500 Hz)
MAX44009 – Light
25 Hz
For further details on sensor parameters, please refer to section 3.5.1
2.2
Global time stamp reference to sensor data
The application allows you to configure an SNTP time server (see Configuration for details) to obtain a global time stamp
for your measurement data. The Synchronization is done once on power-on of the XDK. The device will (re-)try to establish
a connection up to four times (see Table 2: LED pattern of the XDL120 for details). This feature requires WLAN access.
Please make sure to select a time server that is reachable from your local network.
2.3
Online streaming of sensor samples via WLAN
XDL120 allows to stream sensor data live during logging using WLAN, with a focus on high data-rates (see Configuration
for details). The data will be sent via UDP to a host within the same network. Due to the nature of the protocol and the RF
conditions in the target application, this method cannot guarantee package delivery (packet loss may be possible). Please
analyze the time stamp provided to identify lost packages.
2.4
Seamless auto-save
The seamless Auto-save is one of the key feature of the Data Logger / Streamer application. The user can configure the
time interval in which to store the logs in separate files when the Data Logger / Streamer application is configured to log
data to the SD Card. Based on the time interval configured in the config.xml file, a new log file is created for every time
interval. This feature will not interrupt logging and at the same time it saves data. The user can configure the auto-save
time interval from 1 min to 24 hours. Given a configuration of 2 min, a new log file will be created every two minutes.
2.5
LED indication on application state
Four LEDs are available on the XDK and each LED except the green LED indicates a specific state of the application. The
possible LED patterns and their causes are listed in Table 2.
