Category Archives: Programming

Compiling NodeMCU ESP32 Firmware

Recently I’ve been doing some experimenting with the NodeMCU ESP8266 and ESP32-S chips to use in home automation, sending data back to my Samsung SmartThings system. The ESP32 is considered a development board and as such not everything works as expected. One of the issues I was having was the ADC isn’t very linear resulting in some of my analog inputs being pretty far off (over 4%). With that said the firmware is being updated pretty regularly so I wanted to compile a new version. I attempted to follow the instructions available ( but was having trouble. Finally I created a Ubuntu 16.04.3 LTS virtual machine using VirtualBox but then ran into a bunch of other issues since it didn’t have any of the dependencies installed. Well after some experimenting I got it working and here are the steps:

  1. Install Ubuntu 16 (should work with 17 also)
  2. Update it (search for update and launch the software updater)
  3. Drop to a terminal (CTRL+ALT+T), typing each item, and press enter:
    • sudo apt-get update
    • sudo apt-get upgrade
    • sudo apt-get install libncurses5-dev libncursesw5-dev flex bison gperf python-serial
    • sudo apt-get install git
  4. In the same terminal window grab the firmware code: “git clone --branch dev-esp32 --recurse-submodules nodemcu-firmware-esp32
  5. Move to the source directory with “cd nodemcu-firmware-esp32”
  6. Start up the menu using “make menuconfig”

You should now be able to select your config options and save a sdkconfig file that you can use to make the firmware. Now I couldn’t save the sdkconfig in the same directory and ended up saving it to my home directory then making a copy of the modemcu-firmware-esp32 directory, pasting the config in there, and running make from there to compile. I’m assuming this is because I used git to pull down the repo and its read only (compiling from the copy with my sdkconfig worked so I didn’t try to figure it out).

If you want to get fancy you can also share out your USB through VirtualBox and flash the chip from the virtual machine using make flash but I didn’t like that idea so I transferred out the NodeMCU.bin from the build directory to my host machine (Windows 10) and used NodeMCU-PyFlasher-2.0 to flash to firmware. Afterward I found that my ADC’s, while not 100% accurate, were a lot closer. Hopefully they keep making progress on this chip as it seems like a very capable replacement to the ESP8266.

VB.Net Drag and Drop from Outlook

One thing I have been working on for years now is a database program that among other things has a part that lets you attach files into it. The drag and drop functionality was easy for regular files on the hard drive but a feature request came in to drag and drop files from a outlook attachment. Luckily someone had already figured this out in C# which I converted into VB here: This was all fine and dandy until I got a request last week to attach the actual email itself, not a attachment. After more searching I found someone that did this using the Outlook interop libraries here: So after a little more playing I updated my drag and drop code to decipher between a normal file, a Outlook attachment, or a Outlook email and act accordingly.

Couple notes: DisplayMessageBox is a custom message box used by my program (replace with MsgBox if needed) and AddTempFileToArray does exactly that, adds any temp files I create or use to a array which I then delete when my program closes (don’t want a bunch of temp files created and left), and SaveButton is enabled only during a edit operation.

In my control where I will accept the drop:

Private Sub MyControlToAcceptTheDrop_DragEnter(ByVal sender As Object, ByVal e As System.Windows.Forms.DragEventArgs) Handles MyControlToAcceptTheDrop.DragEnter
' Make sure that the format is a file drop.
If (e.Data.GetDataPresent(DataFormats.FileDrop)) And (SaveButton.Visible = True) Then
e.Effect = DragDropEffects.Copy
ElseIf (e.Data.GetDataPresent("FileGroupDescriptor")) And (SaveButton.Visible = True) Then
e.Effect = DragDropEffects.Copy
' Do not allow drop.
e.Effect = DragDropEffects.None
End If
End Sub

And my code to handle the drop:


''' Handle File Drops

''' DragEventArgs ''' Path to the actual file or temp file
''' Returns the full path to the file being dropped or to a temp file that contains the file in memory (for use with Outlook or other program drag drops)
Friend Function HandleFileDrops(ByVal e As System.Windows.Forms.DragEventArgs) As String
If e.Data.GetDataPresent(DataFormats.FileDrop) Then
' We have a file so lets pass it to the calling form
Dim Filename As String() = CType(e.Data.GetData(DataFormats.FileDrop), String())
HandleFileDrops = Filename(0)
ElseIf e.Data.GetDataPresent("FileGroupDescriptor") Then
' We have a embedded file. First lets try to get the file name out of memory
Dim theStream As Stream = CType(e.Data.GetData("FileGroupDescriptor"), Stream)
Dim fileGroupDescriptor(512) As Byte
theStream.Read(fileGroupDescriptor, 0, 512)
Dim fileName As System.Text.StringBuilder = New System.Text.StringBuilder("")
Dim i As Integer = 76
While Not (fileGroupDescriptor(i) = 0)
System.Math.Min(System.Threading.Interlocked.Increment(i), i - 1)
End While
' We should have the file name or if its a email the subject line. Create our temp file based on the temp path and this info
Dim myTempFile As String = Path.GetTempPath & fileName.ToString
' Look to see if this is a email message. If so save that temporarily and get the temp file.
If InStr(myTempFile, ".msg") > 0 Then
Dim objOL As New Microsoft.Office.Interop.Outlook.Application
Dim objMI As Microsoft.Office.Interop.Outlook.MailItem
If objOL.ActiveExplorer.Selection.Count > 1 Then
DisplayMessageBox("You can only drag and drop one item at a time into this screen. The first item you selected will be used.", "One Item At A Time", , FormStartPosition.CenterParent)
End If
For Each objMI In objOL.ActiveExplorer.Selection()
Exit For
objOL = Nothing
objMI = Nothing
' If its a attachment we need to pull the file itself out of memory
Dim ms As MemoryStream = CType(e.Data.GetData("FileContents", True), MemoryStream)
Dim FileBytes(CInt(ms.Length)) As Byte
' read the raw data into our variable
ms.Position = 0
ms.Read(FileBytes, 0, CInt(ms.Length))
' save the raw data into our temp file
Dim fs As FileStream = New FileStream(myTempFile, FileMode.OpenOrCreate, FileAccess.Write)
fs.Write(FileBytes, 0, FileBytes.Length)
End If
' Make sure we have a actual file and also if we do make sure we erase it when done
If File.Exists(myTempFile) Then
' Assign the file name to the add dialog
HandleFileDrops = myTempFile
Call AddTempFileToArray(myTempFile)
HandleFileDrops = String.Empty
End If
Throw New System.Exception("An exception has occurred.")
End If
Catch ex As Exception
DisplayMessageBox("Could not copy file from memory. Please save the file to your hard drive first and then retry your drag and drop.", "Drag and Drop Failed")
HandleFileDrops = String.Empty
End Try

End Function

As you might be able to guess I only look at the first email message if multiple are selected and let the user know that also. I’m sure there is a way to loop through multiple files, Outlook attachments, or Outlook emails but I don’t need that functionality so I didn’t code it (but I did warn in case it happens).