Need personal use info on a DDS function generator.

I designed this a few months ago...

It's nice and small, good for embedded stuff. We have another version that has four more internal arb channels that can modulate or sum into the main four outputs, to do am/fm/chirps/stuff like that.

John

That's nice, It may even be a better choice considering the space we have to mount it.

Is this unit supplied with programming doc's so that it can be incorporated into a software package via the serial port or is there a driver (DLL file) that must be included and thus linked from there or some BDE, COM interface?

The communications is all simple ascii commands, so you'd probably write appropriate code into your application. All you have to do is open a comm port and talk. Things like Hyperterminal work fine for playing, and it has built-in Help. We do have a test program (in PowerBasic) and a sort of virtual instrument Windows thing (java) which we give away, sources included, but most users write their own stuff into their overall application.

Here's the manual, 5 megabytes or so:

ftp://jjlarkin.lmi.net/T346ManA2.pdf

If it looks useful, email me and maybe arrange for a loaner.

jjlarkin atsign highlandtechnology dotto com

This was a lot of fun to do, especially the T346 version that has all the modulations. We got to re-live a lot of the "Signals and Systems" stuff we took in school. I did the hardware design and wrote the internal firmware, and my super FPGA guy did all the core stuff in a Spartan3 and persuaded it all to run at 128 MHz.

We were in trouble on the DAC lowpass filters until we bought the Nuhertz software, which designed an amazing LC lowpass filter in a few minutes. That guy is really smart, but also very, very crabby.

John

Thanks, I just down loaded it, I'll take this to work tomorrow and we'll all have a look at it.

John, how come you don't have a pdf-file datasheet yet?

What do the T344 and T346 cost? I want one, a T346 if we can afford it! I enjoyed the photo of the pcb you put up.

How much of the timing occurs in the 68332, and how much in the FPGA? I can see you can design the circuit and lay out a pcb, etc., but a huge task lies on the uP and FPGA programming and debugging. Not to mention writing the manual and sales literature.

Rob, my FPGA guy, did a lot of the heavy lifting on this one, making everything work at 128 MHz. The interpolation was a nice touch. We negotiated the architecture together. I did the schematic, the 68K firmware (almost 7k lines of assembly, maybe 3 weeks total), the PC-resident test/cal program (a couple of days, PowerBasic), and the manual (another week or so.) We had a friend do the Java Win/Linux virtual instrument demo thing for $10K.

The FPGA does all the realtime stuff, and the 68K does the serial comm, command parsing (438 distinct serial commands!), waveform loading, BIST, configures the fpga, stuff like that. All the calibrations are done by adders and multipliers inside the FPGA, so the uP just plucks the cal factors out of eeprom and loads them into the fpga, which saves a lot of time. Whenever my trusty old 68332 gets too busy, Rob takes a function over from me and does it in the Xilinx.

The T344 is $3960 with power supply, a couple of cables, and ethernet. T346 is $4800. Pricing is the least scientific thing we do.

We really enjoyed doing this one. I hope somebody buys some.

John

Well, I'll certainly buy one. It'll be very useful. I'll contact you by email to setup the Harvard vendor database stuff.