Teensy 3.5 synchronized/latched DAC output?

[florianlink]

Hi,

I was wondering if it is possible to write to both DAC outputs synchronized/latched? Otherwise the outputs will be delayed by the time it takes to call the writeAnalogOuput() method, right? I need fully synchronous outputs for x/y laser galvo control.

Regards,
Florian

 

[Frank B]

That's mechanics - and mechanic is many order of magnitudes slower than the cpu. You could write hundrets of different values before you notice the slightest movement on your lasers.

 

[PaulStoffregen]

The DACs have a clocked mode. I've never actually used it.

Frank's point is valid.

Also consider no matter how fast your system may be, the DACs have limited analog bandwidth. Freescale specs a rise time corresponding to not much more than audio bandwidth. Turns out they're much faster if you don't have significant capacitance loading the pins, but even in a best case scenario the analog bandwidth isn't more than 1 MHz. Writing to both of them only a few dozen nanoseconds apart is insignificant within the scale of their limited bandwidth.

Still, I'd be really curious to hear if anyone can get the clocked mode to work.

 

[florianlink]

Thanks, I only need 22 khz so you are both right, latching is not needed. I was using an external MCP4822 via SPI with the Teensy 3.2 and latching was important there, but SPI was inbetween.