Hacking your coffee maker; building a connected appliance with Netduino and Xamarin

We Power
Connected Things
Hardware development at the speed of software. www.wildernesslabs.co
Bryan Costanich
@bryancostanich

- The dream of connected things
- Controlling household electricity with a
relay
- Exposing control via a web API
- Connecting to that Web API from a
Xamarin App
Building a Netduino Powered
Connected Coffee Maker

Wilderness Labs
Relaunched Netduino in March.
Added Mac support.
Netduino stock at Amazon.com and
Mouser.com (international).
Building a vNext connected things
platform.
Actively working on Netduino.

Connected Coffee Maker
Solution

Power Control
Household electricity (110V/240V) is
controlled by a relay.
Relays are electromechanical and isolate
circuits.
Controlled by a simple on/off via a digital
I/O pin.
Design @ 3D_Print_Designs repo
Assembly instructions in blog.
OutputPort relay =
new OutputPort(Pins.GPIO_PIN_D2, false);
relay.Write(true);

Web Server
Purpose-built for Netduino.
Modern, RESTful Web API/
Built-in JSON Support.

Maple Web Server Host
public class RequestHandler : RequestHandlerBase {
private static bool _isPowerOn;
public void getStatus() { StatusResponse(); }
public void postTurnOn() { TogglePower(true); StatusResponse(); }
public void postTurnOff() { TogglePower(false); StatusResponse(); }
private void TogglePower(bool val) {
_isPowerOn = val;
Ports.ONBOARD_LED.Write(val);
Ports.GPIO_PIN_D1.Write(val);
}
private void StatusResponse() {
this.Context.Response.ContentType = "application/json";
this.Context.Response.StatusCode = 200;
Hashtable result = new Hashtable { { "isPowerOn", _isPowerOn.ToString().ToLower() } };
this.Send(result);
}
}
get:/Status
post:/TurnOn
post:/TurnOff

Xamarin Mobile App
Xamarin.Forms + HttpClient
async private Task<bool> PowerCommand(string command) {
HttpClient client = new HttpClient();
client.BaseAddress = new Uri("http://" + _hostAddress + "/" + _apiBase);
var response = await client.PostAsync(command, null);
if (response.IsSuccessStatusCode) {
if (command == "turnon") {
App.ApplianceStatus = ApplianceStatus.On;
} else {
App.ApplianceStatus = ApplianceStatus.Off;
}
}
return response.IsSuccessStatusCode;
}

Possible Expansion Projects
On timer.
Feedback loop for heat control w/temp sensor; what temp do
you like your coffee?
Coffee done push notification.
Scheduler.

Thanks.
www.wildernesslabs.co
slideshare.net/bryancostanich
Code here
Github.com/WildernessLabs/Netduino_Samples/Connected_Coffee_Maker

Hacking your coffee maker; building a connected appliance with Netduino and Xamarin

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