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PDB & FTM, synchronization of ADC and pulse outputs

Question asked by Benno Jung on Mar 12, 2014
Latest reply on Apr 29, 2014 by Benno Jung



We have some questions about the FTM and PDB module.
I'm working with the Vybrid VF5xx/VF6xx. The documents I've found (VybridRM, VybridSeries, AN4822) are good but not very clear in every point.

We need a lot of time-synchronized signals. This means:
- ADC channels which are sampled in specific time slots
- DAC channels, also set on specific time
- >10 Timer Outputs (timed output pulses, rising and falling edge controllable, jitter-free)
- input capture
- 8 PWM signals


The FTM's can be synchronized to each other. (RM P.1740)
The PDB can be triggered from the FlexTimer. (Do I need a FTM channel for this? Or can it be done by the way?)
So, everything is synchronized so far.
Now, I can trigger the 2 ADC's with 2 PDB channels, each with up to 8 pretriggers for 8 ADC channels each. (Do I need here an Interrupt to set the next ADC channel for next conversion, or is the PDB able to do it by himself?)
Further, I can trigger the 2 DAC's with 2 more PDB channels.
Is this correct so far?

Now the question: With the PDB (4 remaining channels), it is possible to generate pulse outputs. Can they be connected directly to a GPIO output pin? Or how can it be done?
And for further pulse output signals, is it the only way to generate FTM interrupts and set/clear normal GPIO's in the interrupt routine? And then set a new FTM counter value for the next interrupt? (We have not enough FTM channels for combined PWM signals)
The goal is, to use the CPU as less as possible and to have not a lot interrupts. Is there any better way to generate more than 10 synchronized output pulses? (The pulse frequency is about 50 kHz)


I hope someone has already worked with amd can help us with this modules.