I'm prototyping a reset controller for a micro using a CMOS 556 timer IC. The first half is a monostable pulse generator, designed to emit a short HIGH pulse when the reset button is pressed. This resets the uC, but if the user continues holding down the reset button, the uC will resume boot-up and can then read the state of the reset button to perform some action if it's being held down. (Typical press to reset, hold to reset to defaults behavior.)
The problem is, instead of a pulse, the output remains HIGH as long as the reset button is held down.
Attached: The schematics (from a simulator that shows proper behavior), and the PCB layout with a TI TLC556. The left half is the monostable part. Pin 1, 2 are Disch, Thresh, 3 is Control, 4 is Reset, 5 is Out, 6 is Trigger, 7 is Gnd, 14 is Vcc, 8-13 are the other half.
I've measured pin 1/2, and see the cap charging to 3.3v when the button is pressed. It falls to 0v when the button is released. Control is 2.20v. Out is 0v until the button is pressed, then it goes to 3.3v and stays there, only returning to 0v when the button is released. The Out pin goes to the input of a logic IC to OR with a PGood signal from the regulator -- so no appreciable load or anything.
It looks to me like everything's correct. Am I missing something? Is there something particular with the CMOS 555/6 that I'm not taking into account?