Simon Godfrind

Sequential sampling, COCO and lock mecanism of PDB

Discussion created by Simon Godfrind on Jan 25, 2018
Latest reply on Jan 29, 2018 by xiangjun.rong

Dear all,


Considering I have read posts about the question without finding the answer I formulate it here.


Checking the AN5380 "Using FTM, PDB, and ADC on KE1xF to Drive Dual PMSM FOC and PFC"

And reading the behaviour of PDB with the lock mecanism in the "Kinetis KE1xF Sub-Family Reference
Manual" that says: "When a pre-trigger from a PDB channel n is asserted, the associated lock of the pre-
trigger becomes active. The associated lock is released by the rising edge of the
corresponding ADCnSC1[COCO]; the ADCnSC1[COCO] should be cleared after the
conversion result is read, so that the next rising edge of ADCnSC1[COCO] can be
generated to clear the lock later. "

1) I wonder first if there is a way to not being blocked by COCO vs PDB lock to sequentially sample mutliple input then issue an ISR and then reading all the Results at once without the use of DMA (that clears COCO), Average function or Compare function (that prevent COCO from being set).

2) Secondly if it is not possible only, how in AN5380 do they achieve to sample the offset of the Fan Motor at 10kHz? Because in Fig. 5 (copied below), I don't see any ISR that would read specifically the result of it to clear COCO (and unblock PDB CH0DLY1) whereas the ADC continue to sample both PFC currents just after (same question btw between both PFC current sampling) ? I am obviously missing something.


3) Only if not answered regarding the 2 questions before, what would be the best solution to sample 2 signals simultaneously then, after the conversion time, 2 others simultaneously then, after the conversion time, process them into a single ISR? In fact, I'd like to minimise any unnecessary ISR's to release the PDB channel pretrigger lock.


PS: Of course, the access to the whole source code of this application note would make it easier. 


Thanks in advance,