Revision as of 17:00, 22 September 2010

wifi_fast.py is the primary utility for receiving real-time telemetry from the target. It makes connection to the target via either a standard RS-232 serial port, or via a TCP connection. Once connected it reads telemetry, can log the data to a file, and can send the data via UDP for real-time plotting. It also sends keyboard characters to the target which can then be read via the C function 'getchar'.

basic command line options

• get help with wifi_fast.py -h

The typical command contains 3 or 4 options as show below. wifi_fast.py -f log_file_name -V dataport3d -F -i IP_ADDRESS

• -V option specifies a "Vlist" or variable list that describes the binary format of the telemetry packet. These vlist files live in "support_scripts\vlist". Some times matching the vlist to the firmware can be a challenge - as the two need to be precisely the same length; and the variable types must also match.

• -f option specifies the base name of the log file.
  • As data is received, it converted as specified by the #vlist, and stored in a self documenting .txt file that has a time stamp suffix. Several times an hour a new file will be started and the previous one added to a zip file.
  • The zip file often contains a file called "wifiload.m" that can be used with matlab to read the file and create a data structure with named fields. However, there are now easier to use matlab functions for this purpose.
  • The "-f xx" file option is a special case that means no-logging.

• -F : this command line option causes wifi_fast to send a command to the SWIFI for it to flush its FIFO. When there is not connection, this FIFO will fill w/data and may take ~1min to be depleted when full.

• -i, -p : one of these options is required as it specifies how to connect to the target. The -i option specifies an IP address (or resolvable machine name), while the -p option specifies a serial port.

making a connection to the robot

via a wired connection

A wired ASYNC serial connection with the target requires a minimum of 3 wires : GND, Tx, Rx. The signals are 3.3V logical level. Several USB serial port devices called "PSER" have been made for this purpose. When connected to the PC, they will be assigned a "COMM PORT" number. Under windows you can use the "Device manager" to list the serial ports. You can run the command directly with the command "devmgmt"

via a wireless connection

The robot uses a "SWIFI" to make a connection to a 2.4Ghz "G" access point. The SWIFI needs to be pre-programmed to know what access point to connect to.

• In lab the access point is : bmech4.media.mit.edu
  • You can also test connectivity with ping bmech4.media.mit.edu

From the support scripts folder run :

• FOR S3 : wifi_fast.py -i 216 -F -f xx -V dataport
• FOR S5 : wifi_fast.py -i 218 -F -f xx -V dataport

matlab support

A number of helpful matlab scripts and functions live in "support_scripts" and "support_scripts\matlab_support". It is help to add these directories to your matlab path. Setting the path can be done from the "File -> Set Path" dialog from the main matlab window.

plot_float : real_time plotting

The command "plot_float.m" is used to listen to a UDP port, and plot the data received on that port. When started, plot_float prompts for a port number (typically 9999) to listen on. Afterward, it runs the script "user_ui.m" and reads the file "auto_ui_9999.txt" for configuration.

user_ui.m

autu_ui_9999.txt=

reading SWIFI data files with matlab

• wifiload.m
• data = wild(file_name_pattern)
• obj = wild_cvt_dirlist(directory_pattern)

off line plotting data and objects

• pit.m
• gpit.m
• spit.m

vlist