I wish to use a Teensy 4 Quad Timer as both an external signal generator (output) and at the same time capture its current count value from another external signal (input). I want to compare the phases of these two signals - if at all possible. This is easily done with an FTM timer in the Teensy 3 world.

But in reading the Ref Manual CH53 carefully, it looks as though there can only be ONE external interface to a quad timer at any given moment. Can anyone confirm this?

My reason for thinking this may be the case is that register TMRx_SCTRLn on page 3131 bit 0 (OEN) talks about configuring the output "on THE external pin". This suggests there is only ONE external pin (and if its an input, it cannot simultaneously be an output).

Also, when attempting to configure the CAPTURE feature, the IOMUX and XBAR registers never describe the "Capture Input" specifically for the Quad Timers. They do refer to the "Quad Timer Input". I was making an assumption that any input must be the capture pin, but that may not be true (as when timers are chained in series, the second one will need an input). Its beginning to look as though you cannot do "output" and "capture" at the same time...