VT100 Terminal Emulator

VT100 (About Modules) is a VT100 terminal emulator - it takes a series of characters and draws them on a Graphics object, interpretering newline/carriage return/up/down/left/right/etc correctly.

It isn't a full emulator, but emulates enough of a terminal to correctly display everything that comes out of Espruino.

The main use for this is allow you to display Espruino's console on a screen connected to Espruino itself.

To do this you'd want to use LoopbackA and LoopbackB:

// take characters from Espruino, and push them into the VT100 terminal
LoopbackB.on('data',function(e){
  // USB.write(e); // optionally mirror back to the PC
  // Send characters to the terminal
  for (var i in e) term.char(e[i]);
  // update the screen
  g.flip();
});
// copy characters coming down USB into the 'loopback' device
USB.on('data',function(e){ LoopbackB.write(e); });
// Now move the console to Loopback
LoopbackA.setConsole();

For example, assuming you have an LCD connected as described in the Pico LCD Hello World tutorial:

A5.write(0); // LCD GND
A7.write(1); // LCD VCC
A6.write(1); // TLCD backlight

var g; // Graphics
var term; // the terminal

function onInit() {
  // Setup SPI for LCD
  var spi = new SPI();
  spi.setup({ sck:B1, mosi:B10 });
  // Initialise the LCD
  g = require("PCD8544").connect(spi,B13,B14,B15, function() {
    // LCD initialised...

    // Set up the terminal
    term = require("VT100").connect(g, {
      charWidth : 4,
      charHeight : 8
    });

    // take characters from Espruino, and push them into the VT100 terminal
    LoopbackB.on('data',function(e){
      // USB.write(e); // optionally mirror back to the PC
      // Send characters to the terminal
      for (var i in e) term.char(e[i]);
      // update the screen
      g.flip();
    });
    // copy characters coming down USB into the 'loopback' device
    USB.on('data',function(e){ LoopbackB.write(e); });
    // Now move the console to Loopback
    LoopbackA.setConsole();
  });
}

You'll need to manually run onInit() after uploading.

If you were to then add a keyboard to Espruino, you would have a complete computer!

Reference

// Draw an underline under the current character
VT100.prototype.drawCursor = function () { ... }

// Scroll the screen down (if possible, else clear)
VT100.prototype.scrollDown = function () { ... }

// Call this every time you get a character (ch is a single-character string)
VT100.prototype.char = function (ch) { ... }

/* Create a VT100-style terminal.

  g = Graphics to use
  options = object of options: 
    charWidth -> width of characters in pixels
    charHeight -> height of characters in pixels
    marginLeft -> left margin (we have no right margin)
    marginTop -> top margin 
    marginBottom -> bottom margin

After setting up, you can also set:

term.fgCol -> Foreground color
term.bgCol -> Background color
*/
exports.connect = function (g, options) { ... }

Using

Espruino Home Computer