External Clock as input

Is it posible to use the external clock of another controller to Arduino DUE . Like connecting the external clock to PWM pin of the DUE . And trying to measure that clock signal. For example if possible, the frequency is 1Mhz, can a PWM signal be generated in the DUE and accordingly can the LED blink ?

apko dusre PWM pulse ko measure kar k DUE mese same PWM generate karna he kya..???

NO, I want to measure the clock or use the clock of the other controller(ATMEGA) to DUE or make use of the ATMEGA's clock as external clock to DUE . How can I do it? Some measurements with the ATMEGA's clock via DUE. I was planning to generate a PWM signal with ATMEGA's clock in DUE, but I do not know how to begin with it.

Measuring externally generated PWM signal up to 20MHz can be done on Due with antodom's tc_lib:

Can I directly connect the external clock pin to Arduino DUE's PWM pin through wire? Is there any other possibilities of measurements without an oscilloscope?