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Serial Sensor Package (SSP)

Many of our users requested a simple real time interface to an accelerometer sensor. Although our current products support HID transfers, the programming support can be difficult and cumbersome (especially in Windows). We developed a simple serial interface product that will support several different sensor types. The serial sensor package (SSP) establishes a serial connection via a standard USB port. The physical connection to the device uses a micro-B type connector. The SSP is supported by Windows and Linux, and analysis programs, such as MatLab and Labview, will connect directly to the serial data stream. The SSP-x supports the Analog Devices ADXL345 16g sensor used in our X16 series of loggers. The SSP-b includes the Bosch Sensortec BMP085 sensor used in our B1100-1 logger.

SSP-x Accelerometer Features

  • Low noise 3-axis +/-16g accelerometer
  • Low cost, compact size (2"x1"x0.5")
  • User selectable sample rates of 12, 25, 50, 100, 200 Hz
  • 15-bit resolution
  • Easily readable comma separated data stream
  • Micro-resolution feature for 0.1 millisecond timing precision

SSP-b Barometer Features

  • High precision digital pressure sensor
  • Data reported in Pa and includes temperature compensation
  • Low cost, compact size (2"x1"x0.5")
  • User configurable sample rate between 1Hz and 32 seconds per sample
  • Easily readable comma separated data stream

For more details, specifications, and how to use the SSP, please refer to the user manual (.pdf). The user manual includes an example data file and instructions for converting the data and time stamps.

The SSP with Windows XP / 7 / 8

The SSP implements a Silicon Labs CP210 USB serial interface chip. Necessary Windows based software drivers and support are provided by Silicon Labs. The product will appear as a serial comm port and stream text-based data.

comm port

A serial terminal program will display the output of the SSP device. Configure the appropriate COM port to a baud rate of 115200, 8N1, and no flow control. Connect to the port and data is streamed to the terminal window. Send "?" to see a list of available commands from the SSP.

A simple Visual Basic example program captures and plots the serial data (The executable file and source code is available to download).

example code

The SSP with Linux

In Linux, the comm port is easily accessible in the /dev directory. For example, "cat /dev/ttyUSB0" will stream data to the console and "cat /dev/ttyUSB0 | test.csv" will send data to a file named test.csv. Data can be read into "R" using the read.csv function. For example, the command line "input <- read.csv(file="/dev/ttyUSB0", nrows=100,"Time","X","Y","Z"))" will load 100 lines of data into "input" variable.

The SSP work very easily with Linux and the Raspberry Pi. We have two fun examples using the SSP-x and a Pi: