wiki/ RocketView

"RocketView": PSAS Launch Vehicle Telemetry Viewer

Introduction

rocketview is PSAS' telemetry viewer for LV1b and later launch vehicles. LV1b's rocketview was a C/GTK+ application (see the below) and the current LV2 rocketview is a Java SDK 1.2 application.

Specifications


ALL OF THIS STUFF IS OUTMODED? OR?

Yes, most of this should be moved to an old-rockview page. The archictecture and layout of RocketView changes frequently, so it shouldn't be documented here.

Architecture

The Java implementation of our telemetry display software, RocketView, has several components. These are:

CanMuxer Interface

CanMessage and CanSocket are defined as follows.

public class CanMessage
{
  protected short id;
  protected Date timestamp;
  protected byte body[];

  public CanMessage(short id, Date timestamp, byte body[])
  {
    this.id = id;
    this.timestamp = timestamp;
    this.body = body;
  }

  public short getId()
  {
    return id;
  }

  public Date getTimestamp()
  {
    return timestamp;
  }

  public byte[] getBody()
  {
    return body;
  }
}

interface CanSocket
{
  public CanMessage read() throws IOException;
  public void write(CanMessage msg) throws IOException;
  public void close() throws IOException;
}

The TCPCanSocket class implements CanSocket to provide a connection to a running CanMuxer instance.

The LogCanSocket class acts as a filter, passing calls to its methods through to an underlying CanSocket instance, but also logging all CanMessages it sees to a file.

CAN Renderers

The CanRenderer interface is implemented by classes that wish to recieve CanMessages from the dispatcher, presumably in order to display the contents of those messages through a GUI or other user interface. This interface is defined as follows.

interface CanRenderer
{
  public void render(CanMessage msg);
}

CAN Message Dispatcher

The Dispatcher class tracks CAN renderers which have been registered with it and provides an event loop for processing messages from the rocket.

Stripchart Widget

The JStripChart class accepts timestamped numbers and renders them on a scrolling timestamp-scaled scatterplot.

Main Driver

The RocketView class initializes the renderers, lays out a GUI, and passes control to the dispatcher.

Assignments

Nathan Matsuda:

David Cassard:

Greg Cheong:


C/Gtk+ RocketView

This page is an attempt to document Rocketview, our current telemetry display software. Comments and questions are requested to help me make this documentation more complete.

-- ?JameySharp - 09 Jan 2002

The source code for LV1b's version of Rocketview may be browsed online at http://bart.cs.pdx.edu/cvsweb/cgi-bin/cvsweb.cgi/rocketview/ . The new version for LV2 is under development at http://bart.cs.pdx.edu/cvsweb/cgi-bin/cvsweb.cgi/fc/rocketview/ . (As of this writing, the new version is nearly identical to the old one.)

Telemetry transport: can.c

The transport is intended to be the same as that used by CanMuxer, so that no special-purpose software is needed to deliver telemetry data to the ground. Transport details are mostly abstracted by libcan, part of CanMuxer.

The transport handles splitting the telemetry stream into packets, but Rocketview is still responsible for interpreting the data in those packets. This layer selects a RocketView to handle each packet based on the CanBusIDs.

LV1b specifics: serial.c and the packet/ directory

The transport was over radio modems, so Rocketview communicated with a serial port. The protocol used is documented at GroundSupport.

serial.c handled opening and reading the serial port, buffering input until a complete packet arrived, calling the right packet decoder when a complete packet had been read, and passing the decoded packet to a RocketView.

A domain-specific language was created to describe packet formats, including the order, types, and names of the fields in each type of packet. These descriptions were used to generate the packet decoders in the packet/ subdirectory.

Data processing: processor.c

Some calculations are done on the ground before presenting the telemetry data to the user.

The remaining processing involves reporting the data to the right RocketView widgets.

Graphical interface: callbacks.c, message.c, interface.c, support.c

The GUI is written in GTK ( http://www.gtk.org/ ), built using Glade ( http://glade.gnome.org/ ).

Chart widget: gtkchart.c

BartMassey wrote a custom stripchart widget for this project.

Authors

BartMassey wrote the original GUI code. ?JameySharp wrote the original packet parsing and processing code. Both collaborated to complete the result.