An Unconventional Loudspeaker system Latest change 2019-01-01
TestTool-TPA can be used to test several functions of the TPA
board and the Power board.
The tool contains an Arduino Nano with exactly the same software
as on the FLT. The software finds out that is is running on the
TestTool by the status of pin D4. On the FLT it is GND, on the
Tool it is open.
The Flatcable is to connect to the TPA board under test. The USB
connector on the Arduino must be connected to a PC on which the
program TestTool_TPA runs. The white cable has an RCA connector
and should be connected to an audio signal generator. The 6-pole
header can be connected to a Power board if that has to be
tested too. The TPA board should have its supplies +12 and +50
The green led upper left indicates TPA in reset. The other leds
are the same as on the FLT board, blue = CPU, yellow =
Communication, red = Error.
Screenshot of the program TestTool_TPA.
In this picture the TestTool was not connected to a TPA board,
but it was supplied with 12 Volt.
Upper left a checkbox to enable the solid-state switch on the
Power board, if one is connected. The field Mains Fail will be
green if the Neon tube is on, other wise red.
Supply Fail reflects the status of the Supply-Fail bit in the
FLT status byte. However this bit is forced to OK when the FLT
firmware runs on the test tool.
Fault and OTW show the status of these lines of the TPA3255
chip. OTW will be red if the Clip_OTW line is longer that 2
seconds low, which indicates the Over Temperature Warning.
Clips indicate the number of clipping events modulo 256. Clr
will clear the clipcounter.
Reset TPA brings the TPA3255 chip in reset mode, clearing any
error condition. On the right the measured voltages +5A, -5A,
and +5D are the supply voltages on the TestTool. +50V and +12V
are the voltages on the TPA board.
More at the bottom is a field to enter the serial port name
and a checkbox to enable communication. If a wrong serial port
name is entered an error message appears. After clicking these
away another name can be entered. When the tool is properly closed the
last used serial port name will be saved and retrieved when
the program starts again.
Below that we have counters for incoming and outgoing
messages and textboxes displaying the contents of the messages
in decimal byte values.
On the bottom line a textbox indicating the Operating System on
which the program runs.
Schema The schema is mainly a subset of the
The TestTool is supplied by the
+12V from the TPA board, the Arduino is suplied by the USB
The board has not been routed as a real PCB, this layout was
made to help hand-wiring it.