Nuts and Volts - February 2018

ADVANCED TECHNIQUES FOR DESIGN ENGINEERS

is touched, B4RSerializator converts a two-byte command array to bytes and sends it over the astream output data pipe (socket.OutputStream). Looking back at the B4R code, we see that the

n PHONESHOT 3. The blue LED graphic tells us that the D0 I/O pin of the WEMOS D1 Mini is logically high, or ON in the OFF state.

The status message returned from the WEMOS Mini server consists of the button touched and the status of the associated Mini output pin. The button touched is decoded by B4RSerializator as data(0), and the status of the output pin is decoded by B4RSerializator as data(1). The blue D1 Mini application is looking for commands S0, S1, and S2 in array form.

When the Mini server receives our button command string, it toggles the associated I/O bit and returns a status message to the client iPhone. The iPhone application processes the incoming status message using the Astream_ NewData subroutine:

Private;Sub;Astream_NewData;(Buffer();As;Byte)
 data;=;ser.ConvertBytesToArray(Buffer)
 Select;data(0)
 Case;“S0”
 If;data(1);=;True;Then
 imgvLedD0.Bitmap;=;(LoadBitmap(File.
DirAssets,;“blueledon.png”))
 Else
 imgvLedD0.Bitmap;=;(LoadBitmap(File.
DirAssets,;“blueledoff.png”))
 End;If
 Case;“S1”
 If;data(1);=;True;Then
 imgvLedD1.Bitmap;=;(LoadBitmap(File.
DirAssets,;“blueledon.png”))
 Else
 imgvLedD1.Bitmap;=;(LoadBitmap(File.
DirAssets,;“blueledoff.png”))
 End;If
 Case;“S2”
 If;data(1);=;True;Then
 imgvLedD2.Bitmap;=;(LoadBitmap(File.
DirAssets,;“blueledon.png”))
 Else
 imgvLedD2.Bitmap;=;(LoadBitmap(File.
DirAssets,;“blueledoff.png”))
 End;If
 End;Select
End;Sub

I Leave You Illuminated

I touched button S0 and was presented the iPhone view you see in Phoneshot 3. I checked the voltage at pin D0 of the Mini and it was indeed at + 3.3V.