The Hackpack v4 by default boots into a UI which assists you on your journey at SIGNAL.

That walled garden isn’t the end of the road, however—we’ve made it very easy to break out of our guided experience. Simply text hp <URL> to 744625 (or international 1.586.474.4625) to move the HackPack to a page of your creation.

This guide will show you (most of) the low level API we’ve exposed to you. The UI is HTML, CSS, and Javascript inside a Python webview—and there are a number of goodies in Python we’d love you do grab.

Here’s how to grab them.

Python Webview and Hardware Specifications

While designing for the webview, you’ll need to be aware of its specifications (and the limits of the hardware).

To change from MOUSE (default) mode to ARROW mode, there is a utility function in the Python API inputArrow.

After 21 seconds, the Hackpack will reset to MOUSE mode; we suggest calling ARROW mode every 5-7 seconds to keep the Hackpack input in that mode.

Python Methods Available to Call

Every function is called in the same way, with a method name and a JSON object. For many functions the JSON can be empty, but take heed of the ones which expect some kind of input. For example, you can call a light pattern with:

pywebview.api.showLightsParams({'demo': 3, 'repeat': 2});

We’ve created three classes of functions for you to call with your web app:

Utility Methods

Function Sample Call Description
checkWifiConnection pywebview.api.checkWifiConnection({}); Check if WiFi is up
get pywebview.api.get({'key': 'test'}); Get a key from Hackpack local storage
getIpAddress pywebview.api.getIpAddress({}); Get the device IP address
getRandomNumber pywebview.api.getRandomNumber({}); Get a random number
inputArrow pywebview.api.inputArrow({}); Set input type to ARROW mode (for 21 seconds)
inputCursor pywebview.api.inputCursor({}); Set the input type to MOUSE mode (default)
lightsOff pywebview.api.lightsOff({}); Send a 'Lights Off' sequence and clear any stored sequence
longTime pywebview.api.longTime({}); DANGER. Pause webview for 15 seconds
set pywebview.api.set({'data': '12345', 'key': 'test'}); Set a key in Hackpack local storage
setLightIntensity pywebview.api.setLightIntensity({'intensity': '30'}); Set light intensity [0-100] in Percentage. ‘15’ is default.
wifiPowerManagementOff pywebview.api.wifiPowerManagementOff({}); Turn off WiFi power management
wifiPowerManagementOn pywebview.api.wifiPowerManagementOn({}); Turn on WiFi power management

Basic Method

Function Sample Call Description
changeWebView pywebview.api.changeWebView({'url': 'https://www.twilio.com'}); Move the URL on the HackPack. Wherever you point it, tap the escape/power button 3 times to go back.
launchDoom pywebview.api.launchDoom({}); Launch Doom
launchMicropolis pywebview.api.launchMicropolis({}); Launch Micropolis
launchOpenTTD pywebview.api.launchOpenTTD({}); Launch OpenTTD
showLights pywebview.api.showLights({}); Show the scanner pattern (default)
showLightsParams pywebview.api.showLightsParams({'demo': 3, 'repeat': 2}); Show a demo [0-39] and repeat X times. You can find the demos here. (SPOILER ALERT)
textLights pywebview.api.textLights({'message': '128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,4000'}); Set the lights to a color (R,G,Bx5 then delay in ms). The command to the left is full white for 4 seconds.

Advanced Method

Function Sample Call Description
addLightCommand {'message': '128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,4000'} Send CUSTOM light command directly to lightsocket. For examples, see here.
clearLightSequence {} Clear the currently stored light commands.
lightLights {} Send a 'Show Lights' Command

Other Methods

There are some other methods exposed through the Python API. However, we don’t suggest calling them because they are destructive in various ways, or lower level than you really need for functionality.

Using the Python API

The Python-Javascript bridge doesn’t immediately load with your page. Additionally, you’ll probably be testing your webapp on the desktop; you’ll want to use defensive coding to ensure it is loaded.

This example defensively calls a light sequence every 5 seconds with jQuery:

$(document).ready(function() {
    var maxRetries = 5; // maximum number of times to look for the PyAPI
    var delay = 5000; // in milliseconds
    var have_python_api = false; // useful in other parts of the code

    function rejectDelay(reason) {
      return new Promise(function(resolve, reject) {
          setTimeout(reject.bind(null, reason), delay);
      });
    }

    function lightDemo(retry) {
      try {
        pywebview.api.showLightsParams({'demo': 3, 'repeat': 2});
      } catch(ex){
        if (retry < maxRetries) {
          setTimeout(function() {lightDemo(retry + 1);}, delay);
          return;
        } else {
          console.log("> Too many retries. Are you not in the webview?");
          return;
        }
      }

      // Successfully called lights, call them again soon
      setTimeout(function(){lightDemo(-1); have_python_api = true;}, delay);
    }

    setTimeout(function() {lightDemo(0);}, delay);
  });

Go Forth and Hack the Hackpack!

Hackpack v4 was designed to hand over the reigns to your ingenuity and creativity as quickly as possible. We fully encourage you to poke around with these commands and the firmware.

If you have any questions, don’t hesitate to visit us at the Hackpack booth… we’d be thrilled to help.

And, as always, we can’t wait to see what you build. (And watch it flash.)