If you're a Tsunami backer, what do you have in mind for your Tsunami? Have you got particular tasks or challenges in mind? Something custom you want to write? Tell us!
The first thing I'll use my Tsunami for is a pretty generic kind of use. I've designed and built a radio direction finding "fox" as a project. Normally, you build a few of these to hide in different places, and set a timer for them to go off later.
If you want the transmitters synchronize well hours later, you need to calibrate the clock crystals (and the circuit design has a small trimming cap on each one for this purpose). There are lots of ways to do this, but it strikes me that the easiest is probably just to program each microcontroller to expose the frequency on a PWM pin and measure it with the Tsunami.
That's an excellent application. I've been hoping people will make use of the Tsunami's unusually good frequency reference.
Have you considered making the trim digitally controlled? If it were, you could generate a frequency reference with the Tsunami and apply it to an input pin, allowing the device to tune itself until it's in sync with the reference signal.
Also, I hope you've accounted for temperature effects on the device's frequency?
Well, since I've already made a set of boards and built one up I'm not likely to go back and make them digitally trimmed. I also didn't make them temperature compensated, figuring that 3 boxes stashed in the same geographical area are likely to endure similar temperatures.
Really, all I need is "fairly accurate" clocks. Since foxes tend to take turns transmitting a minute or two apart, I don't want the clock of one fox to drift away from the other foxes by so much that they overlap.
Of course I'd prefer if each 32K crystal were precisely 32768 cycles per second, so that tomorrow each fox goes off at exactly the desired moment. But more important is that the difference between the clock of one fox and another is small. They can all go off a minute late as long as they still take their turns correctly.
Fair enough! Many MCUs have built in temperature sensors, which you could use to further increase accuracy if you were so inclined anyway.
A couple of other simple tasks had occurred to me. A square wave is very convenient for measuring the velocity factor or electrical length of coax. An ideal project would use both the generator and the detector so I don't need to pull out the oscilloscope. But that wouldn't be essential. Just a program to measure the delay on the reflected waveform would pretty much nail it.
Measuring caps and inductors would also be handy.
Tuning the oscillators in my Eurorack synth (both to each other, and also in absolute terms to an accurate 440Hz reference)
Measuring the frequency response of recording studio equipment
Capacitance and inductance measurement
Finding out the exact frequency of the crystal on various other Arduino (and compatible, such as Teensy 3.x) boards by running a sketch to create a square wave at a frequency derived from the clock frequency, then measurig what is actually produced. Run tests at various temperatures.
- Tune a VLF antenna to try to receive NAA signal
- As a low frequency signal generator
Fantastic ideas! I'm glad to hear that the TCXO is going to get a workout.
A friend of mine with far too much test equipment has been doing some informal tests on a prototype board, and reports that the TCXO is living up to expectations: between room temperature and 70 degrees, it varied by all of 2 millihertz!
Excellent performance - excited!
Any initial results on stability over time?
Not yet! The datasheet suggests 1ppm aging per year.
To clarify, I was meaning more the drift/1000 hours type of stability. Naturally you don't have per-year data for such a recent product
I've been looking to build a programmable voltage source to use for testing some A/D converters. Would the Tsunami be able to fit that niche?
That depends - what voltage range do you need to test it over, and what are your accuracy requirements?
Hi, I'm new to everything Arduino (but not to electronics). I would like to know if the Tsunami is suitable for the following (seems so to me, but like I said, being new, I could be just wishful thinking).
I'm building a direct drive motor for a turntable--its an axial flux coreless motor, designed by me, unique in the world (four phases for one thing). To drive it I was thinking of a simple cd4046 pll, a frequency reference and some motor drivers. Seems like I could usefully use the high precision frequency ref in the tsunami. Once I have the tsunami seems like its not a stretch to program it to also be the phase-locked loop and, of course, the motor driver would still be external. The input to the tsunami would be a hall-effect sensor on the motor.
Sound do-able? Waste of time?
You can certainly use the Tsunami to generate variable frequency sine or square waves. You could also program in a digital phase-locked-loop via the input circuitry; what would the input signal source be?
Well, there are actually two modes. Simplest is no input at all; no PLL. In this mode the DDS outputs some waveform at exactly the desired rpm * 15 * 8, where those magic numbers come from the motor rotor/stator geometry.
Second mode uses feedback to create a PLL. The input comes from a hall-effect sensor mounted somewhere on the motor. It will probably need something like a schmitt trigger to clean up the transitions. There would be 30 transitions per revolution.
Sounds totally doable. The Tsunami input already has a schmitt trigger on the frequency counter input, so you're sorted!
Goodies package arrived today, yay! Testing it later in the evening.
My original need was just a signal generator and I almost bought cheap one from eBay, luckily I saw Tsunami before ordering. Signsl generation is still my "main intended use" for it.
The precise clock I'm going to use at least to calibrate attinys, especially their internal clock.
All the other possibilities are open, but the device looks too cool, I'm sure it won't collect dust!
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