Anyone familiar with using the Arduino Due? I am using one in the project
published here
http://www.nutsvolts.com/magazine/article/the-arduino-graphics-interface-part-1
<http://www.nutsvolts.com/magazine/article/the-arduino-graphics-interface-part-1>
It uses the Due's DMA-driven DAC outputs to produce signals to drive an XY
graphic display. The circuit is very simple. Just buffers on the inputs and a
sample/hold blanking arrangement to smooth out the DAC output.
I find that the circuit manages to destroy DAC0 output, though I can not
discern why. Each DAC feeds a 10k/4.7k voltage divider before the buffer
inputs; this should not be an excessive load. I bought the board from Nuts and
Volts so I haven’t made a breadboard mistake. There is no measured low
resistance on the DAC0 or DAC1 inputs on the board, nor is there any voltage
offset there.
If v/div is cranked up high enough, the output can still be seen on DAC0, so I
think the DAC is actually fine and the issue is perhaps an output transistor or
even a multiplexer.
Using a very simple for loop instead of the Nuts and Volts code does not fix
the problem once it happens.
void loop() {
for (int i = 0; i <256; i++) analogWrite(DAC0,i);
for (int j = 0; j <256; j++) analogWrite(DAC1,j);
}
Anyhow, there are some search hits online which suggest there is some sort of
fragility with the output for DAC0. An ATSAM3X8E bought domestically costs
almost as much as a complete Chinese knock-off Due, so I think I will not be
attempting to replace them. I’ve ruined two already, so I think this project is
going to go into the trash so that I may move on with my life, so to speak.
Nuts and Volts forums are a ghost town and have no info on the project.
Sometimes it may be best to just take a hammer to things so that you may
prevent yourself from throwing away more time on it.
If someone has a Due they can stand to sacrifice, I would be interesting in
seeing if the problem can be solved by feeding the board DAC inputs with 10K
resistors instead of jumper wires from the DAC output pins. It really should
not be that fragile, but maybe it is.
Alex_______________________________________________
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