What are you doing with the file once you have read it?

Regards,
Mark

Hi Mark,

These data files (daily) are records of the engine consumption that sample every 1 mins.
Currently the record format is as follows: [mins since today's 00:00] | [Double variable with 3 decimal places]

Regards,
Alex

Hi Stefan, If I don't do the readtoend method, the process will be very slow and it will cause exception from my interrupt (8 pulse inputs). Do you have any codes on how to do file seek? Maybe, I can use your method, but need to call the read file many times using the seek method to remember where I left off on the previous call.

Hi Guys, Currently I have developed a near to completed application on the N+ using Netduino firmware (to get the extra RAM). But only today, I realise N+ has a problem reading text file (with around 500 records) of size around 12Kb. I need to read back for historical reporting on daily basis. I am using the streamreader.readtoend method, but it will throw SystemOutofMemory. I also tried using the pre-define size buffer(1024) to read block by block, but still meet the same exception. I also tried using the readline method together with stringbuilder library to join each readline returns. But still hit the same exception. Then I finally give up. I have to reduce my sampling interval to ensure the daily file size is around 6K instead, then everything goes well. Just like to check anyone out there has a better idea how to handle large text file data log files? Thanks in advance. Regards, Novice Alex

It all depends on the file format. Since you're writing daily stats? You could do several things:
- Make records an X amount of bytes large
- Create a file format that works with data blocks
- Create an index

I have too little information right now to really be able to help you out.

Hi Stefan,

That's sound like a good idea. Since each records is fit by the format [mins since 00:00 of the day] | [Double value with 3 decimal place]. I can fix string format for both. And use ReadBlock to do it. However, need to do some testing to see whether it improve in processing.

in fact, currently when I read back the full content, I will then pass the full file content (as string) back to the caller for further parsing and then determine the require range (report time start to end) and accumulate the total value in the field (2) - Double.

Regards,
Alex

Hi Guys,

Anyone try to the following declaration in VB using VS2010.

Public Const INFINITE_DATE As Date = #12/31/9999#

I am using the above declaration for my program to do comparison. But once I declare it, the VS2010(VB) will crash and need to restart.

I have also tried to set the date to today date, example #07/21/2012#, it will still restart the VS.

That's an interesting find!
Could you please make an issue at http://netmf.codeple...item/list/basic ?
I can indeed reproduce this and it should never happen.

Hi Stefan,

good to know that you too is facing the same problem.
As suggested, I have make an issue @ codeplex.

Thanks.

Thanks, I voted for the issue too

Hi Stefan,

They have taken up the issue and fixes is schedule for NETMF 3.0

Hi Guys, Just to share my experience that I encounter today. I have been doing real-time debugging when developing my project. But out of a sudden, I am no longer able to kick off any debugging, which means all my break-points are not trigger. after much effort, include erasing the Netduino and reflash the firmware v4.2 also can not solved. Only after I open the project.user file (in my case vmas-mini.vbproj.user) and include the last statement <DebugType>full</DebugType> in the <PropertyGroup> tab. Everything is back to normal. I can now do the debugging as per normal. Regards, Alex

Hi Chris, I remember the SD card corruption happens after around 7 days of "burn test". I have been trying to do "hot swap" for newly design PCB to see any effect on the system reliability. Then it starts to hang the whole N+. After putting in a few debug statement, it came to know that it was hang during the writing to a data text file. I have tried to do file deleting on the SD card on my PC, but it still exists after I do a screen refresh. So, no choice but to reformat it. I suppose it can be caused by the loss of power during the writing (while doing the "hot swap"), but how can we recover from there if such incident happens again, given that this system will be deployed to remote sites out in the sea, so it will be quite trouble to access. From my attached class, is there any potential problem that you can foresee? Thanks in advance. Regards, Novice Alex

Hi Guys,

I have done up a commercial project and now doing the "burn test".
This project suppose to do data logging of the fuel consumption from different flow meters on a 5 mins interval.
However, I found that randomly the log file could be corrupted and it will cause the whole N+ to hang when accessing it.
I have tried to access the SD card using my PC and can see that that particular "problem" file exists but I am not able to access it and I can't delete it from my PC. So the only way is to reformat my SD card and start fresh. This gives me some sense of "uncertainty".

Does anyone know how can we handle such cases to avoid the N+ to hang? By the way, when I say hang, it means not even when I short the reset pin to ground or press the reset can restart N+, the only way is to power it down completely.

Below is my SD card class library.

Imports System.IO
Imports SecretLabs.NETMF.Hardware.Netduino
Imports SecretLabs.NETMF.Hardware
Imports Microsoft.SPOT


Public Class cSDCard
#Region "Enumeration"

#End Region

#Region "Declaration"
    Public Shared Event LastError(ex As Exception)
    Public Shared Event SDEject()
    Private Shared m_bSDEjected As Boolean = True
#End Region

#Region "Property"
    Public Shared Property SD_Ejected() As Boolean
        Get
            Return m_bSDEjected
        End Get
        Set(value As Boolean)
            m_bSDEjected = value
        End Set
    End Property

#End Region

#Region "Method"
    Public Shared Function MountSD() As Boolean
        MountSD = False
        SD_Ejected = True
        Try
            SecretLabs.NETMF.IO.StorageDevice.MountSD("SD", Microsoft.SPOT.Hardware.SPI.SPI_module.SPI2, 21, 57)
            Dim dirinfo As New DirectoryInfo("\SD")
            If (dirinfo.Exists) Then
                MountSD = True
                SD_Ejected = False
            End If
        Catch ex As Exception
            SD_Ejected = True
        End Try
    End Function

    Public Shared Function UnMountSD() As Boolean
        Try
            If SD_Ejected = True Then
                Exit Function
            End If

            SecretLabs.NETMF.IO.StorageDevice.Unmount("SD")
        Catch ex As Exception

        End Try
    End Function

    Public Shared Function ReadFile(sFilename As String, ByRef sContent As String, Optional bReadLastLineOnly As Boolean = False) As Boolean
        ReadFile = False
        Try
            Dim lFileSize As Long = 0
            Dim sTmp As String = ""
            sContent = ""
            If SD_Ejected = True Then
                Exit Function
            End If

            If File.Exists(sFilename) Then
                Dim myFile As New StreamReader(New FileStream(sFilename, FileMode.Open, FileAccess.Read))
                If bReadLastLineOnly = True Then
                    While (1)
                        sTmp = myFile.ReadLine
                        If Not sTmp Is Nothing Then
                            sContent = sTmp
                        Else
                            Exit While
                        End If
                    End While
                Else
                    sContent = myFile.ReadToEnd
                End If
                myFile.Close()
            Else
                Debug.Print(sFilename & " not found!!!")
            End If

            ReadFile = True
        Catch ex As Exception
            RaiseEvent LastError(ex)
        End Try
    End Function

    Public Shared Function WriteFile(sFilename As String, sContent As String, Optional bAppend As Boolean = True) As Boolean

        WriteFile = False
        Try

            If SD_Ejected = True Then
                Exit Function
            End If

            Dim myFile As StreamWriter

            If bAppend = True Then
                myFile = New StreamWriter(New FileStream(sFilename, FileMode.OpenOrCreate, FileAccess.Write))
            Else
                DeleteFile(sFilename)
                myFile = New StreamWriter(New FileStream(sFilename, FileMode.CreateNew, FileAccess.Write))
            End If
            myFile.WriteLine(sContent)
            myFile.Close()

            WriteFile = True
        Catch ex As Exception
            RaiseEvent LastError(ex)
        End Try
    End Function

    Public Shared Function DeleteFile(sFilename As String) As Boolean
        DeleteFile = False
        Try

            If SD_Ejected = True Then
                Exit Function
            End If

            If File.Exists(sFilename) Then
                File.Delete(sFilename)
            End If
            DeleteFile = True
        Catch ex As Exception
            RaiseEvent LastError(ex)
        End Try
    End Function
#End Region
End Class

Thanks in advance.

Regards,
Alex Chan

Hi Guys, I am in a project to monitor some flow meters at the same time doing some remote monitoring. In my project, I have a class object for flow meters which is controlled and monitored by the main program loop that will send back current flow meters pulse counters on every 5 seconds. The question is which of the following method require more resource from N+? 1. On timer (5 seconds) interrupt in the each of flow meter object, I will raise a NewData event (passing back the current flow meter pulse counter) for my main program to handle them separately. 2. On timer (5 seconds) interrupt in my main program, i will called the public property in each flow meter to get the current flow meter pulse counter. Then handle them accordingly. Generally, just wonder is it better to use raise event method or pull method? Thanks in advance. Regards, Novice Alex

Hi Alex,


They're both valid approaches and consume roughly the same number of MCU cycles. Threads are lightweight so I would go with option #1 purely because it simplifies your code. In effect, you just become a consumer of NewData...and as the way that that data is gathered changes your main code can stay the same.

If there's additional logic to your operation (such as needing to always read flow measurements in a certain order) then #2 becomes a good option.

Chris

Hi Chris,

Well noted.

Hi Guys, Need your advice on how to release COM2(CTS, RTS) pins for more GPIO purpose? Currently for my project, I need 2 COM port, but we usually use 3-wire interface, so just like to check how can I release CTS and RTS pins for my other GPIO purpose. Thanks in advance. Regards, Novice Alex

The general rule-of-thumb with microcontrollers is that pin assignments aren't always restricted to their architectural labelling. For example, a pin maybe labelled as PWM(Pulse Width Modulator) which would normally tie-in with a hardware clock and hardware interrupts. By default, the pin doesn't function as a PWM unless you actually configure it to be.

Much the same with the CTS and RTS pins, you can configure them as OutputPorts or InterruptPorts. If you try to use them for two purposes, you'll get a runtime exception when trying to initialise the pin for a second use. Example of using the RTS pin as a GPIO pin

SerialPort comPort = (SerialPorts.COM2, 9600, Parity.None, 8, StopBits.One); //Initialise COM2
OutputPort oPort = new OutputPort(Pins.GPIO_PIN_D7, false); //initialise the RTS pin as an output port with logic low as initial value;

Hi Nobby,

wonderful... That clears my doubts.
Just for knowledge, how can I configure PIND7 as RTS, do you have the code for it?

Thanks in advance.

Hi Nobby, Below is my statement. m_objCommMgr = New cCommManager("COM2", 9600, Ports.Parity.None, 8, Ports.StopBits.One) so far, I have not connected RTS and CTS since i am only using 3 wire interface. Since on the board layout, for COM2 it comes with RTS and CTS (derived from GPIO pins), I just wonder if we can disable these RTS and CTS when using COM2. Thus giving my project the much needed GPIO to measure the pulse input. Care to share how do you initialise your COM2 without RTS & CTS? Thanks in advance.

Hi Moskus,

Can you please post a bug report on this at netmf.codeplex.com?

There are a number of post-release bugfixes being checked into the .NET MF 4.2 codebase. We're hoping to pull a bunch of them in at once and make a Netduino 4.2 RC4 firmware update...so it would be great to get this one in too.

Chris

Hi Chris,

Any timeline for the RC4 firmware?
Please advise.

Novice Alex

Does Interger.Parse("0") not work ?

Does any try out the above using the 4.2 RC4?

Hi Guys,

I am trying to setup a PWM to generate constant pulse for my monitoring project.
Below are the codes.

Public WithEvents Supply As InterruptPort
Public PWM_Supply As New SecretLabs.NETMF.Hardware.PWM(Pins.GPIO_PIN_D5)

Supply = New InterruptPort(Pins.GPIO_PIN_D0, False, Port.ResistorMode.PullUp, Port.InterruptMode.InterruptEdgeHigh)

Dim period As UInt32 = 1 * 1000 * 1000 '1 seconds
Dim duration As UInt32 = 5 * 100 * 1000 '0.5 seconds
PWM_Supply.SetPulse(period, duration)

After executing the last command "SetPulse", the below exception will be trigger
A first chance exception of type 'System.InvalidOperationException' occurred in Microsoft.SPOT.Hardware.PWM.dll

Can anyone highlight the problem in this declaration?
Thanks in advance.

Regards,
Novice Alex

Hi Chris, Just like to know what are the ways to encrypt our program code in the N+ to prevent others from decrypt it? I have completed a commercial project and would like to protect the program. Please advise. Regards, Novice Alex

Hi Novice Alex,

Let me start with a few tips and let others chime in as well...

Since .NET code is a close approximation to C# source, you may want to look at a program like Dotfuscator which will help keep your code from getting decompiled easily. NETMF HEX files are already one step away from standard MSIL DLLs, but in theory they're still MSIL.

My second recommendation is to add a security key to your deployment file (using MFDeploy) and using an "RTM" version of NETMF firmware to lock out any debuggers This will help make sure your board uses signed firmware.

We use direct flashing and custom boot loaders for commercial projects...but we can search around for some documentation on MFDeploy's signing/encryption methods if needed.

Chris

Hi Chris,

Noted. Just like to know that steps for the MFDeploy, is it that I only need to selected the "encrypted" exe and it will deploy to the correct segment of the N+? So far, I only use MFDeploy for the firmware upgrades procedures.

Also for the security key, how and what are the steps on implementing it?

Sorry for my ignorance and thanks for the advice in advance.

Regards,
Novice Alex

Hi Chris, Just like to know if it is possible to release more code space if I would to drop the network portion, since for my project, I don't really need it. But I am using Netduino+ because of the SD card reader onboard. If so, how can I go about on loading the firmware, which once should I use? Please advise. Thanks in advance.

Hi Novice Alex,


You can safely use the regular Netduino firmware on your Netduino Plus.

To do this you will want to: erase your board by applying 3V3 power to the gold erase pad underneath D0; flash TinyBooter using Atmel SAM-BA; flash the NETMF runtime using MFDeploy.

Full instructions are available on the Wiki.

Once you flash the regular Netduino firmware on your Netduino Plus, you can use the SecretLabs StorageDevice class to ".MountSD" and re-enable SD card access.

Chris

Hi Chris,

Thanks for your quick response.
I will try and revert if there is any problem.

So after this flashing, I suppose I have 128KB code storage size together with 60KB RAM, right?

Hi Novice Alex,


You can safely use the regular Netduino firmware on your Netduino Plus.

To do this you will want to: erase your board by applying 3V3 power to the gold erase pad underneath D0; flash TinyBooter using Atmel SAM-BA; flash the NETMF runtime using MFDeploy.

Full instructions are available on the Wiki.

Once you flash the regular Netduino firmware on your Netduino Plus, you can use the SecretLabs StorageDevice class to ".MountSD" and re-enable SD card access.

Chris

Hi Chris,

Just like to double confirm. I have successfully update the Netduino firmware onto my Neduino+. So when I start a project, do I set it as Netduino/Netduino+ project? Also in my case, do you have any sample code on mounting the SD card.
Also by using Netduino firmware on access SD card, will i be giving up any digital pins access?

Separately, do I need to mount & un-mount the SD card everything I use? Or only for once during system power up?

Thanks in advance.

Hi Guys,

Just to share with you guys on my experience on the upgrading to 4.2.
After flashing my Netduino+ I execute the MFDeploy, it does not show the device when I select USB connection.

Then I realize i did not install the latest .NET Micro Framework v4.2 SDK (QFE2).
You may download from here

After installation, reset your netduino and plug it it, you should see the device in the MFDeploy application and continue your firmware upgrade.

Good luck.

Regards,
Alex

Make a call to Math.Pow( a, b )

Do note that latest version does not work for this function.