12 synchronized pulses

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jonr

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I need to generate 12 pins of output pulses, all independently positioned in time; but also with each one being repeatably (1 ns jitter) positioned with respect to the others.

A single FTM can produce 4 pins of low jitter rising and falling edges (using COMBINE mode). Is there a way to synchronize multiple FTMs to get more synchronized outputs? Maybe using an external clock. Or some other idea?
 
....you know what 1ns is ?

(1 / 1ns) = what frequency ? :)
(hint: Light travels 30cm/12inches in one nanosecond )

Don't know wether the teensys pll is good enough for this.. it might be worth to take a look into the datasheet..

edit:
i was curious :) The Datasheet says: 600ps@100MHz..1350ps@48MHz accumulated over 1us
 
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Section 36.4.28 starting on page 896 documents a "Global time base" feature. I have not personally used this feature, but from the info in the manual, it certainly sound like it does what you want.

FTM1 and FTM2 have only 2 channels each. Even with all 3 timers, if you want to control the positions of both rising and falling edges, only 12 channels sounds like only half of the signals you wanted.

Frank's point about the PLL jitter is good. I've spent quite a bit of time looking waveforms on my scope, which admittedly has only 200 MHz bandwidth. I believe you'll get close.

But the other thing to consider is the FTMs run from the 48 MHz "bus" clock, not the main system clock. With a 48 MHz reference, your timing step size will be slightly over 2 ns.
 
Ah, so far fewer channels than I thought. Thanks.

It works quite well for 2 channels using FTM0. Resolution is 20.83 nsec and jitter is about as low as my 1 Gsps scope can show.
 
I wonder if two teensys could run off the same cpu clock and therefor stay synchronized within a ns.
 
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