Learning About Arduino and VNC

Introduction

Implementation of a VNC server on an Arduino Ethernet board.

Code

First cut, should display a blank window: VNCServer_001.pde

Version 002, bell, clipboard, one colourful frame: VNCServer_002.pde

Version 003 tidied from above, but with a cycle of colours: VNCServer_003.pde (delayed upload, not recently tested)

Project Log

( 28 March 2009 )

Have only just realised that both Arduino and Processing define the Server.available method as meaning "Gets a client that is connected to the server and has data available for reading ." So there's no way to retrieve a client that has connected but not yet sent any data—which means all data transfer has to be initiated by the client. Which is a problem with a protocol like VNC where the server is expected to respond to the connection with data.

Added a cut & paste hack job to enable retrieval of a client that has connected but not yet sent data. @@ TODO: Submit bug report & proper patch.

Add to Server.cpp :

#if 1
Client Server::connected()
{
  accept();

  for (int sock = 0; sock < MAX_SOCK_NUM; sock++) {
    Client client(sock);
    if (EthernetClass::_server_port[sock] ==_port && 
        client.status() == SOCK_ESTABLISHED) {
        // XXX: don't always pick the lowest numbered socket.                   
        return client;
    }
  }

  return Client(255);
}
#endif

Add to Server.h :

#if 1
  Client connected();
#endif

Successfully connected with "Chicken of the VNC" client to display 0/port 5900:

Mar 28 03:12:23 XXXXX Chicken of the VNC[24645]: Server reports Version RFB 003.003

Successfully displayed a blank window, uploaded code:

Successfully sent back a "bell" instruction so the computer beeps, sent back clipboard content "Hello" and updated the display:

The screen update is painfully slow as it's all going one byte at a time, with the associated packet overhead. Definite progress though.

Resisting the temptation to implement input handling too, will aim for sleep instead.

Uploaded latest version of hacky code, compiled size 5360 bytes.

Learning About Arduino and VNC

Introduction

Code

Links

Project Log