Can't get grip on PA1 interrupt

[sthvw]

Hi,

I fell in love with this cute little uC and created all kinds of succesfull projects.
Now I have a problem. I want to decode DCF77 time signals. I bought me a few DCF77 receivers from China. They all work fine. I connected the data output of the DCF77 to the STM8S103 uC portpin PA1. I configured the port interrupt to only react on high-going edges. Even if the PA1 signal is low, when enabling the PA1 interrupt more than 1 interrupts are executed. I tried many things.
- inside the interrupt handler dummy read the GPIOA->IDR
- inside the interrupt handler keep track if its the first or next entry it turns out also the next entry is executed
- changed the interrupt type to raising-edge-only, same behaviour

But nothing helps,
who can help me out?

[sthvw · Accepted solution]

Well, as nobody replies, and after some more investigation I will answer myself. It turns out that when configuring a port-pin as Input-Float then an interrupt is generated continuously even if the pin is connected to GND or VCC. When configuring it as Input-Pullup then it behaves as expected.

Thanks for watching.