Retrigerable Monostable Multivibrator that fires on both rising and falling edge.
Combining a debounce (2 cross coupled nand gates) and two negative edge detectors gets something like this.



The circuit uses a small footprint, low voltage version of the 4011 quad 2 input NAND (74LVX00 or similar) and suitable values for R and C (to create the monostable pulse widths). A third nand gate combines the two pulses into a single pulse train and the final nand gate inverts the signal giving two complimentary outputs