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Fez Cerberus and HW Watchdog in Visual Basic


I’ve spent probably upwards of 10 hours or so searching online for a way to implement the Hardware watchdog using Visual Basic Code. I’ve found several references to how to do it in C#, but I just can’t find a reference to how to do it using visual basic code.

As soon as I try to include GHI.Premium.Hardware I receive this error on compile:

“An unhandled exception of type ‘System.Exception’ occurred in Microsoft.SPOT.Hardware.dll”

Any assistance with this would be greatly appreciated.



@ michaelb - welcome to the forum
can you show us your code ?


The reference above is for the GHI Premium library. The Cerberus uses the OSHW libraries. You need to use references to the OSHW libraries.


Here is a basic snapshot of what I’m doing, I’ve trimmed back a lot of the extra variables ect.:

Imports GT = Gadgeteer
Imports GTM = Gadgeteer.Modules
Imports Microsoft.SPOT.Hardware
Imports GHIElectronics.Gadgeteer.FEZCerberus
Imports System
Imports Gadgeteer.Modules.GHIElectronics
Imports System.Math

Namespace GadgeteerApp2

Public Class Program
    'Public COUNT As Int32
    Dim intRecievedIndex As Int32 = 0
    Dim bytRecievedData(16) As Byte
    Dim bytrecieved(16) As Int32
    Dim Out1 As GT.Interfaces.DigitalOutput
    Dim Out2 As GT.Interfaces.DigitalOutput
    Dim Cout() As GT.Interfaces.DigitalOutput = {Out1, Out2}
    Dim RTUout() As Byte = {23, 24}

    Public Sub ProgramStarted()
        Cout(0) = breakout.SetupDigitalOutput(GT.Socket.Pin.Three, False)  
        Cout(1) = breakout.SetupDigitalOutput(GT.Socket.Pin.Four, False) 

Here is some of where I was trying to set up the Watchdog with no luck, if I ignore the “Premium” version, (and take out the comments) this compiles, but never forces a reset

        'Set up timer for Watchdog
        'Dim spTimeout As TimeSpan = New TimeSpan(0, 0, 0, 0, 1) ' Set up the Timeout to be 15 minutes (or 1 ms for testing)
        'Watchdog.Timeout = spTimeout ' Apply the timeout period
        'Watchdog.Behavior = WatchdogBehavior.HardReboot
        'Watchdog.Enabled() = True

        Thread.Sleep(200)           'Needed to avoid glitches of not opening correctly
        AddHandler rs232.serialPort.DataReceived, AddressOf DataReceivedHandler
        Debug.Print("232 open")
    End Sub

Please let me know if any more is required.


Have you tried the code in this document?

Get this working before Gadgeteer.

Also, you should never sleep in the ProgramStarted method. This causes all sorts of problems. You should do your initialization and exit.


Hi Mike,
Thanks for the assistance, and yes I had looked at that code, but every time I tried to run it, I would run into issues with it not liking the premium library. That said, your initial post about the OSHW libraries was extremely helpful, and now I have code that works as such below:

Load the correct HW library

Imports GHI.OSHW.Hardware

Initialization of the Registers. This is for the IWDG, there is another at 40002C00

    Dim WDKR As GHI.OSHW.Hardware.LowLevel.Register = New GHI.OSHW.Hardware.LowLevel.Register(&H40003000) 'Correct Address of the IWDG timer for the Fez Cerberus
    Dim WDPR As GHI.OSHW.Hardware.LowLevel.Register = New GHI.OSHW.Hardware.LowLevel.Register(&H40003004) 'Prescaler, bottom 3 bits.
    Dim WDSR As GHI.OSHW.Hardware.LowLevel.Register = New GHI.OSHW.Hardware.LowLevel.Register(&H4000300C) ' // Not needed , gives status for being able to adjust the prescaler
    Dim WDLR As GHI.OSHW.Hardware.LowLevel.Register = New GHI.OSHW.Hardware.LowLevel.Register(&H40003008) '' // Watchdog Count down value, default FFF

**The next section sets up the timeout, WDPR is the prescaler from with 1= /4 & 7=/256
**WDLR is the countdown amount from 1 to FFF

   WDKR.Write(&H5555) 'Enable the changing of WDPR or WDLR 
   WDPR.Write(&H7)   'Change the prescaler to divide by 256, currently set for 30s

   WDKR.Write(&HCCCC) ‘Start the Watchdog Timer

**Quick Subroutine to refresh the watchdog time.

Public Sub ResetCounter()
End Sub

I have tested this, and it works great.
I also need to give credit to Sambo’s post for pointing me in the right direction.


@ michaelb - I am glad that it works…

one tip for the next post :

use the “101010” button to format the programcode