Added beeper.amx that simply beeps when it detects a voltage on input. Also gives 1 V voltage on waveout, so with two probes it can be used to check conductivity of e.g. PCB traces. https://github.com/PetteriAimonen/QuadPawn/wiki/Beeper
The calibration app, is this just for pawn apps or is it the same calibration that can be done in the dso firmware and its effect is system wide for the entire device and its apps?
Yeah I have been thinking about it for a while but haven’t had time to implement it.
Should be quite easy atleast to write to serial, because a simple printf() from the code is enough. Reading will require some IRQ routine so that it will store the characters as they arrive.
So I can send data with simple printf() but no read? Thats enough for data log but not control.
I took the sample voltmeter code and created a large number display to use like a DVM. The code is not pretty but I was amazed at how much more accurate readings are in pawn compared to the normal or alternative software.
I wonder what could be done with pawn if it was the main app. Use all the slots for pawn.
Kind of. Not yet Pawn bindings for the function. But maybe I’ll find time to add it soon
Yeah after being calibrated it should be quite accurate. Maybe one day I’ll bother porting the calibration stuff to main firmware. It’s not complex, I don’t understand how the main firmware calibration manages to suck so bad.
Flash is no-longer restricting, but the RAM size is. Pawn as a language is not very powerful, if there will be a more powerful version of DSO Quad one day I’d like to run Lua or Squirrel on it.
And because Pawn is interpreted, it’ll always be limited to the simpler stuff. I couldn’t imagine writing a complete oscilloscope app in pawn; it would simply be too slow.
That would be great. Let me know if you need beta tester.
The one thing I noticed is that I must calibrate on battery power. If I calibrate while powered by USB it is off. Maybe gabonator1 could use the same method for calibration in the alternate firmware.
I have decided to use pawn on the DSO to make a capacitor checker. Simple RC circuit timer. Use waveout to power and wave-in to measure voltage drop over time. I think it may also be possible to measure the internal resistance of the cap too.
Good to know! I haven’t noticed that, but it makes sense as the 3.6V supply voltage is not regulated. It may be that the battery charge level also affects it a bit. But it shouldn’t be very large effect because it is only the opamp supply voltage and not any reference voltage.
Nice! Perhaps the 51 ohm internal resistor on the waveout is enough, so you don’t need separate resistor for the RC timer?
I wonder if it could be used to improve accuracy more. Compare current voltage against that of when it was calibrated. Would need to test at various voltages to check for linearity but I think it could be an improvement to your already good calibration system.
I doubt 51 ohms would work across a wide enough range but it will need to be considered in the calculations.
Indeed. Or maybe we are lucky and the behaviour is somehow predictable between units; then it could just be compensated without calibrating each device separately.
Based on rough calculations, it would have some chance of working for capacitances 100nF and higher.
Not sure if ESR measurement will be possible without external FET; theoretically one could pull the waveout low, but the difference in voltage will be very small. The AC mode at 50mV range could work here.
You have hardware that is able to capture 1180 samples in that time. So I was thinking something like this:
Set waveout to output square wave @ 10Hz.
Set wavein to capture @ 72MHz in free-running mode (DC 500mV) and start the capture synchronously. This means the capture will start when waveout starts a new period.
Then you could fit the exponential function to the captured data and compute the capacitance from that.
You will have to adjust the sample rate for higher capacitances though. Because the usable sample buffer is only about 3500 samples, it will only store 50 microseconds @ 72MHz.
I was just going to do a simple RC circuit. Your method will work and not require external parts. I will switch gears and duplicate with my test equipment first and then reproduce in pawn.
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