Netduino: Using Ethernet Shield to Read/Write to SD Card

After successfully running a program that writes a file to SD card and then reads the content I've decided to summarize all the steps required in order to use Netduino with Ethernet Shield and SD card.

First, you have to upgrade the firmware (I used v4.1.1.0 Beta 1 which can be found here. The detailed instructions about firmware upgrade are available at the same address.

Next, you have to solder ICSP pin on your Netduino board and connect D4 with D10 with jumper wire as it is shown on pictures below.





After adding the ICSP header and jumper wire, the hardware is ready and you can write a program to use the SD card reader. Below is the example I used for test and it worked fine.

using System;
using System.Threading;
using Microsoft.SPOT;
using Microsoft.SPOT.Hardware;
using SecretLabs.NETMF.Hardware;
using SecretLabs.NETMF.Hardware.Netduino;
using SecretLabs.NETMF.IO;
using System.IO;

namespace NetduinoSD
{
    public class Program
    {
        public static void Main()
        {
            StorageDevice.MountSD("SD", SPI.SPI_module.SPI1, Pins.GPIO_PIN_D10);
            using (var filestream = new FileStream(@"SD\dontpanic.txt", FileMode.Create))
            {
                StreamWriter streamWriter = new StreamWriter(filestream);
                streamWriter.WriteLine("This is a test of the SD card support on the netduino...This is only a test...");
                streamWriter.Close();
            }

            using (var filestream = new FileStream(@"SD\dontpanic.txt", FileMode.Open))
            {
                StreamReader reader = new StreamReader(filestream);
                Debug.Print(reader.ReadToEnd());
                reader.Close();
            }

            StorageDevice.Unmount("SD");


        }

    }
}

The whole solution for Visual Studio 2010 can be found here

Retrieving Cell Informations using Google Location API

Recently I examined the records of events stored on my phone. The list contained the informations about MCC (Mobile Country Code), MNC (Mobile Network Code), LAC (Location Area Code) and CellID from which it is possible to get the informations about the mobile cell's location.

Below is the code that retrieves the data from Google Location API with JSON.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Newtonsoft.Json;
using System.Net;
using System.IO;

namespace CellLocations
{
    public class GoogleService
    {
        public GoogleCell GetCellInfo(string lac, string mnc, string mcc, string cellID)
        {
            HttpWebRequest myReq = (HttpWebRequest)WebRequest.Create("https://www.google.com/loc/json");
            myReq.Method = "POST";
            myReq.ContentType = "application/jsonrequest";
            string postData = "{\"cell_towers\": [{\"location_area_code\": \"" + lac +"\", \"mobile_network_code\": \"" + mnc + "\", \"cell_id\": \"" + cellID + "\", \"mobile_country_code\": \"" + mcc + "\"}], \"version\": \"1.1.0\", \"request_address\": \"true\"}";
            myReq.ContentLength = postData.Length;

            StreamWriter stOut = new StreamWriter(myReq.GetRequestStream(), System.Text.Encoding.ASCII);
            stOut.Write(postData);
            stOut.Close();

            HttpWebResponse webresponse;
            webresponse = (HttpWebResponse)myReq.GetResponse();
            Encoding enc = System.Text.Encoding.UTF8;
            StreamReader loResponseStream = new StreamReader(webresponse.GetResponseStream(), enc);

            string Response = loResponseStream.ReadToEnd();
            loResponseStream.Close();
            webresponse.Close();

            GoogleCell cell = JsonConvert.DeserializeObject(Response);
            return cell;

        }
    }
}

In order to deserialize the received data an appropriate class has to be created:

public class GoogleCell
    {
        public GoogleCell() { }
        public GoogleCell(string mnc, string mcc, string lac)
        {
            this.Mnc = mnc;
            this.Mcc = mcc;
            this.Lac = lac;
        }
        public string Mnc { get; set; }
        public string Mcc { get; set; }
        public string Lac { get; set; }
        public string CellID { get; set; }
        public Location location { get; set; }
        

        public class Location
        {
            public Location() { }
            public Location(string latitude, string longitude, string accuracy)
            {
                this.latitude = latitude;
                this.longitude = longitude;
                this.accuracy = accuracy;
            }
            public string latitude { get; set; }
            public string longitude { get; set; }
            public string accuracy { get; set; }
            public Address address { get; set; }

            public class Address
            {
                public Address() { }
                public string country { get; set; }
                public string country_code { get; set; }
                public string city { get; set; }
                public string street { get; set; }
                public string street_number { get; set; }
                public string postal_code { get; set; }
            }
        }
    }

The JSON library for .NET is available here.