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FEZ Panda and USB Host

March 24th, 2011 14 comments

As I promised in my previous post, I would show you how to get USB Host working on the FEZ Panda.

FEZ Panda - USB Host Cable


When I first glanced at the LPC2387 datasheet (the ARM on the Panda), I notice that it actually supported USB Host. Then I thought why it wasn’t possible to use USB Host on the Panda, and I quickly found out that it was because it required some hardware modifications.

USB Cable Wiring


The difference in the hardware between USB Client and USB Host is that the Host is powering the Client, and the Panda had a protection diode so no power would go “out” the USB port. Another thing to notice is that USB Host requires two 15K resistors to pull D+ and D- to ground.

FEZ Panda - USB Host cable wiring


SMD solution
So how did I do it? I didn’t want to modify the FEZ Panda board, as the USB port would then be a permanent USB Host port. Instead I thought it would be nice just to have a cable for the USB Host thing, which should include the two resistors, and a power wire for the +5V power supply.
The first image in this post is my cable, and the second image shows the connections, where there is soldered two 15K SMD 0805 resistors inside. This took a long time to make because it was so small, and SMD resistors can’t handle much force. On a longer term basis it would be better to make an adapter PCB instead.

USB Host cable Schematic

Above you can see the simple schematic of the changes that has to be made to the cable, including where to solder/connect the two 15K resistors.

Thru Hole solution
Instead of using SMD resistors I recommend you to use Thru Hole resistors, and they can handle a lot more force, and the joint will also be more reliable.

FEZ Panda - USB Host Cable


The assembly method is the same as with the SMD resistors. If you don’t have any 15K resistors in hand, we have also tested it with a 12K instead, and everything seems to be running fine with that too.

FEZ Panda - USB Host cable wiring


Oh, and please notice the USB Mini-B to USB Female A adapter at the end. This can be bought at Amazon for $1.87!

USB Connector Pinout


After I made the cable the last thing I had to do was to update the firmware on the FEZ Panda, as the firmware (USBizi) for the FEZ Panda, didn’t support USB Host until V4.1.5.0, though the processor did. After I uninstalled the old firmware/SDK, downloaded the new one, and installed it, I was ready to update the firmware. I just followed this simple Youtube guide:

After the firmware was updated, I connected a cable from the MODE pin to GND to enable Serial Port (COM1) debugging, as the USB port will now be used for USB Host functions.
Then I just followed the “USB Host – Mass Storage” chapter in the Beginners Guide to .NETMF.

To help you guys getting started, I used this code to test the USB Host function. The applications outputs which device is connected, and if a Mass Storage device is detected, the files- and folder tree is shown too.

using System;
using System.Threading;

using Microsoft.SPOT;
using Microsoft.SPOT.Hardware;

using GHIElectronics.NETMF.FEZ;

using Microsoft.SPOT.IO;
using GHIElectronics.NETMF.IO;
using GHIElectronics.NETMF.USBHost;
using System.IO;

using System.IO.Ports;
using System.Text;


namespace FEZ_Panda_Application1
{
    public class Program
    {
        static bool ledState = false;
        static OutputPort led = new OutputPort((Cpu.Pin)FEZ_Pin.Digital.LED, ledState);

        static SerialPort UART = new SerialPort("COM2", 115200);


        // Hold a static reference in case the GC kicks in and disposes it
        // automatically, note that we only support one in this example!
        static PersistentStorage ps;

        public static void Main()
        {
            UART.Open();

            WriteSerial("Starting...");

            // Subscribe to RemovableMedia events
            RemovableMedia.Insert += RemovableMedia_Insert;
            RemovableMedia.Eject += RemovableMedia_Eject;

            // Subscribe to USB events
            USBHostController.DeviceConnectedEvent += DeviceConnectedEvent;
            USBHostController.DeviceDisconnectedEvent += DeviceDisconnectedEvent;
            // Sleep forever
            //Thread.Sleep(Timeout.Infinite);

            int read_count = 0;
            byte[] rx_byte = new byte[1];

            while (true)
            {
                // read one byte
                read_count = UART.Read(rx_byte, 0, 1);
                if (read_count > 0) // do we have data?
                {
                    //WriteSerial("I recieved: " + (char)rx_byte[0]);
                    switch ((char)rx_byte[0])
                    {
                        case 'W':
                            WriteSerial("Writing content to test file:");
                            WriteTestFile("Hello there!");
                            WriteSerial("   Hello there!");
                            break;
                        case 'R':
                            WriteSerial("Reading content from test file:");
                            WriteSerial("   " + ReadTestFile());
                            break;
                    }
                }
            }
        }

        static void DeviceConnectedEvent(USBH_Device device)
        {
            string USBDeviceType = "";

            switch (device.TYPE)
            {
                case USBH_DeviceType.HID:
                    USBDeviceType = "HID";
                    break;
                case USBH_DeviceType.Hub:
                    USBDeviceType = "Hub";
                    break;
                case USBH_DeviceType.Joystick:
                    USBDeviceType = "Joystick";
                    break;
                case USBH_DeviceType.Keyboard:
                    USBDeviceType = "Keyboard";
                    break;
                case USBH_DeviceType.MassStorage:
                    USBDeviceType = "Mass Storage";
                    break;
                case USBH_DeviceType.Mouse:
                    USBDeviceType = "Mouse";
                    break;
                case USBH_DeviceType.Printer:
                    USBDeviceType = "Printer";
                    break;
                case USBH_DeviceType.Serial_CDC:
                case USBH_DeviceType.Serial_FTDI:
                case USBH_DeviceType.Serial_Prolific:
                case USBH_DeviceType.Serial_Sierra_C885:
                case USBH_DeviceType.Serial_SiLabs:
                    USBDeviceType = "USB to Serial converter";
                    break;
                case USBH_DeviceType.Sierra_Installer:
                    USBDeviceType = "Sierra Installer";
                    break;
                case USBH_DeviceType.Unknown:
                    USBDeviceType = "Unknown";
                    break;
                default:
                    USBDeviceType = "Unknown";
                    break;
            }

            WriteSerial("USB Device connected: " + USBDeviceType);
            WriteSerial("ID: " + device.ID + ", Interface: " + device.INTERFACE_INDEX + ", Type: " + device.TYPE);

            led.Write(true);

            if (device.TYPE == USBH_DeviceType.MassStorage)
            {
                WriteSerial("Mounting Mass Storage...");
                ps = new PersistentStorage(device);
                ps.MountFileSystem();
            }
        }

        static void DeviceDisconnectedEvent(USBH_Device device)
        {
            WriteSerial("USB Device disconnected...");
            led.Write(false);
        }

        static void RemovableMedia_Insert(object sender, MediaEventArgs e)
        {
            WriteSerial("Storage "" + e.Volume.RootDirectory + "" is inserted.");
            WriteSerial("Getting files and folders:");
            WriteSerial("");
            if (e.Volume.IsFormatted)
            {
                WriteFilesAndFolders(e.Volume.RootDirectory, e);
            }
            else
            {
                WriteSerial("Storage is not formatted. Format on PC with FAT32/FAT16 first.");
            }
            WriteSerial("");
        }

        static void RemovableMedia_Eject(object sender, MediaEventArgs e)
        {
            WriteSerial("Storage "" + e.Volume.RootDirectory + "" is ejected.");
        }


        static string[] files, filesSub;
        static string[] folders, foldersSub;
        static void WriteFilesAndFolders(string path, MediaEventArgs e)
        {
            files = Directory.GetFiles(path);
            folders = Directory.GetDirectories(path);
            WriteSerial("Files available on " + path + ":");
            for (int i = 0; i < files.Length; i++)
                WriteSerial("   " + files[i]);

            WriteSerial("Folders available on " + path + ":");
            for (int i = 0; i < folders.Length; i++)
            {
                WriteSerial("   " + folders[i]);
                WriteSerial("");
                WriteSubFilesAndFolders(folders[i], e);
            }
        }

        static void WriteSubFilesAndFolders(string path, MediaEventArgs e)
        {
            filesSub = Directory.GetFiles(path);
            foldersSub = Directory.GetDirectories(path);
            WriteSerial("Files available on " + path + ":");
            for (int i = 0; i < filesSub.Length; i++)
                WriteSerial("   " + filesSub[i]);

            WriteSerial("Folders available on " + path + ":");
            for (int i = 0; i < foldersSub.Length; i++)
            {
                WriteSerial("   " + foldersSub[i]);
                WriteSerial("");
                WriteSubFilesAndFolders(foldersSub[i], e);
            }
        }

        static void WriteTestFile(string dataToWrite)
        {
            if (VolumeInfo.GetVolumes().Length < 1) return;
            // Assume one storage device is available,
            // access it through NETMF
            string rootDirectory = VolumeInfo.GetVolumes()[0].RootDirectory;
            FileStream FileHandle = new FileStream(rootDirectory + @"\hello.txt", FileMode.Create);
            byte[] data = Encoding.UTF8.GetBytes(dataToWrite);
            // write the data and close the file
            FileHandle.Write(data, 0, data.Length);
            FileHandle.Close();
        }

        static string ReadTestFile()
        {
            if (VolumeInfo.GetVolumes().Length < 1) return "No Mass Storage found!";
            // Assume one storage device is available,
            // access it through NETMF
            string rootDirectory = VolumeInfo.GetVolumes()[0].RootDirectory;
            if (!new FileInfo(rootDirectory + @"\hello.txt").Exists) return "File not found!";
            FileStream FileHandle = new FileStream(rootDirectory + @"\hello.txt", FileMode.Open, FileAccess.Read);
            byte[] data = new byte[100];
            // write the data and close the file
            int read_count = FileHandle.Read(data, 0, data.Length);
            FileHandle.Close();
            //Debug.Print("The size of data we read is: " + read_count.ToString());
            //Debug.Print("Data from file:");
            //Debug.Print(new string(Encoding.UTF8.GetChars(data), 0, read_count));
            return new string(Encoding.UTF8.GetChars(data), 0, read_count);
        }
        static void WriteSerial(string StringToWrite)
        {
            // convert the string to bytes
            byte[] buffer = Encoding.UTF8.GetBytes(StringToWrite + "\r\n");
            // send the bytes on the serial port
            UART.Write(buffer, 0, buffer.Length);
        }
    }
}

This video is just an example of what you can use the USB-host functionality for:

Update
Kristian has succesfully connected the PS3 Controller to the FEZ Panda, for more information, take a look at his post.

Categories: ARM, USB Tags:

FEZ Panda

March 24th, 2011 2 comments

Last week I recieved a new product, the so called FEZ Panda.

FEZ Panda from GHI Electronics


The FEZ Panda is an ARM7 board, in an Arduino-form-factor, running the .NET Micro Framework. This makes it possible to develop the applications inside Visual Studio using C#. Debugging is also done thru Visual Studio and in my opinion it is very easy to get started.

The great thing about the FEZ Panda, compared to a normal Arduino is the features and the speed.

FEZ Panda features


Instead of a simple 8-bit processor, this is a 32-bit ARM processor clocked at 72MHz. This makes it a monster compared to the Arduino series! The board contains 4 COM ports, 2 SPI ports, real SD interface, a lot of PWMs, Analog inputs (ADC), Analog outputs (DAC), I2C, CAN, USB Client, USB Host – you name it.
Inside the ARM processor, the .NET Micro Framework is running, which includes a FAT filesystem stack. This makes it possible to connect FAT formatted SD card or USB memory sticks to the board.

With this board you get a lot of power and a growing community. There is a lot of examples included, and many more can be downloaded from the .NET Micro Framework projects page.
GHI Electronics, who is the manufactor of this board, has other boards running .NETMF too. They have a bigger version of this FEZ Panda, but still in the Arduino-form-factor, called FEZ Domino
This board is almost twice as expensive, but in my opinion you don’t get twice as much – only a USB Host connecter and an SD card slot. You actually have far less IO’s on the FEZ Domino than on the FEZ Panda, which I think is bad. So I recommend you to try the FEZ Panda!

In my next post I will show how to use the “hidden” USB Host function on the FEZ Panda – as it isn’t stated as supported on the product page, the ARM processor support both USB Host and Client. The only thing it requires, is a little USB Cable tweaking and a firmware update of the ARM to the latest firmware from GHI Electronics.

Categories: ARM, Development boards Tags:

Generating a VGA signal with an FPGA

March 22nd, 2011 34 comments

I posted this video on Youtube long time ago, but I forgot to write about it on my blog.

In the video I demonstrate how the Basys2 board, with a Spartan-3E 100K, can be used to generate a VGA signal.
I also show my bouncing ball application.

You can download the Xilinx project files here, including the VHDL files and User Constraint File for the Basys2 board.

Categories: FPGA Tags: