we dont use symbol tech stuff anymore, jeeze, that was the rage when I was a Kid in 1988. real galvos are now available at less then 200$ and up. Perhaps as low as 120$.
PWM is the easy way to kill your galvos. They will try to follow the PWM waveform, not its average. Its best to ouput the actual beam path using a DAC chip, not PWM and use galvos with feed back and analog driver amplifiers.
What you want to do in your post is called "open loop" and is big disapointment when you get it working, as modern galvos do not have 80's style torsion bars as part of their construction to return the shaft to zero. So since modern galvos and modern symbol tech stuff have no centering means and nothing to to act as a integrating spring, , there is nothing to integrate the PWM signal and you get garbage, the galvo will tend to flop between two positions and not draw anything. Yes, I know modern symboltech has a centering coil, but it does not integrate. Besides symboltech gets you about 200 pps, which is useless in the modern scheme of things.
Here, this project's code is useful, using a older AT MEGA family, easy to adapt:
scroll down to "building a controller"
http://elm-chan.org/works/vlp/report_e.html
Skip the build your own galvos step, its much easier to purchase. However read it to get a idea of how modern galvos work, althout modern galvos use LEDs and Photodiodes to sense position, not the 70's and 80's style RF. Dont get me wrong, many systems made now use RF, but only for really precision slow laser marking applications.
PL USER "Shobbley" here has used the TLV series chip you mention to control his laser harp, he had a few problems at first with the code not being obvious from the data sheet. But other then that it works fine.
Where are you located? we can pair you up with someone close by and you can get a look at some working hardware?
And if you buy a dac chip, try to make sure its "double buffered" , ie x and y outputs update at the same time in hardware. With high speed galvos and 20-30 kPPS , not updating at the same time shows up as minor glitches in the image.
Steve