Parallax USB Data Logger Test

Parallax USB Data Logger

Brett Russell

Description and Use

                  The Parallax USB Data Logger is used by the Arduino microprocessor to read or write data to a USB drive using serial transmissions.  The Arduino programming environment, as of version 1.0 released December 2011, has a built in class to allow this type of communication from any if its digital ports called SoftwareSerial.  This class allows any digital ports to communicate to the Vinculum chip; this chip requires a separate set of commands sent to it in a string, character or ASCII code format. (http://www.parallax.com/dl/docs/prod/comm/VDAPFirmwareSpec.pdf) 

                  This components interfacing to the Arduino requires more code than wiring, noted in the Testing section.  A pin out diagram as well as an overhead image can be seen below. Parallax USB Data 

Logger Data Sheet:

 http://www.rlx.sk/parallax/MemoryStickDataloggerV1.1.pdf

                  We are using the data logger in UART, or Universal Asynchronous Receiver Transmitter, protocol that requires ASCII characters to be sent or received in a serial signal from the Arduino.  These transmissions from the Arduino are sent through the Vinculum chip and encoded into digital signals in order to communicate with the data logger.  The data logger also has a Vinculum chip on board to decipher the ASCII code sent and handle the file system on the USB stick. 

Testing

  The most time consuming aspect of this component is the programming, which the Arduino syntax has the appearance of Java but has header files denoting a C programming language. 

              

Once done writing to the file, you must close out the file by sending a command to the Vinculum chip.  If you neglect to close the file computers will not be able to read the file, let alone Excel.  All data on the USB drive may be compromised if such a situation arises, so be sure to try code out on an empty or pre-backed up drive.

Further testing of the Parallax USB Data Logger must be performed to ensure its abilities at low temperatures when insulated.

Integration into Payload

This component will need to be soldered directly to the circuit board, if that is the path we choose to go, and have its soldered connections protected from impact stress.  Otherwise the chip will have to be situated in a location where there will be no stress on the USB card plugged into it.  Also this particular data logger is rated to operate above zero degrees Celsius, so it will have to be insulated from the harsh exterior environment of the upper atmosphere.