IRQ on a rising edge of an EXTI line sometimes does not come. On a falling edge it always comes.
The MCU is STM32F401CB.
VDD is 3.3V.
A few buttons are connected to PA0 (configured as EXTI rising/falling interrupt).
When a button is pressed, the IRQ always comes.
When a button is released, the IRQ comes rarely, if at all.
There's a filtering cap and a pull-up (100k) at each button.
With the cap at 1nF, IRQ at the rising edge comes (sometimes more than once).
With the cap at 100nF, IRQ at the rising edge almost never comes.
I suspect it might be due to the voltage slope being too flat (large cap loading thru large resistor).
How do I verify this is the case?
Or maybe its something else?
Where do I find EXTI line IRQ electrical characteristics -- I looked in the TRM and the datasheet, only found the minimal pulse width required for the IRQ to be triggered.
Thanks in advance
--
Tomasz Wozniak
