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Continuous Overwrite of C(n)V register with FTM Input Capture

Question asked by Andy Berger on Jul 20, 2018
Latest reply on Jul 20, 2018 by Andy Berger

I would like to continuously capture both rising and falling edges on two separate pins using dual edge capture on an FTM module on a K64. Is it possible to set up the capture registers C(n)V to be continuously overwritten, even if I am not reading the register and clearing the CH(n)F bit with each new edge?


I can't afford to service each edge as it comes in, so my goal is to fire an ISR on the FTM overflow, and then read the input captured time of the most recently-received edge, which could be on any of the four registers (corresponding to rising or falling edges on each of my two pins). From Fig. 40-83 in the K64 Reference Manual, it is not clear whether I need to clear the CH(n)F and CH(n+1)F registers in order to capture the next edge.


Figure 40-83. Dual Edge Capture - Continuous mode for positive polarity pulse width measurement