Hardware Time Delay Reset Activation?

[SaccharinGoat]

Hello, all. First time posting.

I am designing a project that involves a raspberry pi and a microcontroller, when the microcontroller starts up it might pull some pins high or low for a brief moment. I want to be able to use the reset pin on the raspi to restart it after it has been shut down but I do not want the pi to be unexpectedly shutdown and the filesystem corrupted.

I want to design a circuit so that when the input has been active for a second or two it activates the output and triggers the reset pin. Optimally this is made from transistors for low BOM cost.

I have looked at using 555 circuits and watchdog timer ICs but they are both too expensive for my taste on Digikey.
The most promising option seems to be an RC timer hooked up to some Darlington transistors, but the rise time is not fast enough for me (>50ms @350ms delay and scales with increased delay)

Anyone have any advice?

[Terry Bites]

Remind me not to go for a beer with you.

You might look at single gates in SC-74A-5 eg 74LVC1G14GX 18cents!

[SaccharinGoat]

Man, its gonna be tough soldering that X2SON5 package but I think this is the best solution. I looked at schmitt trigger inverters/buffers but only on Digikey. Mouser has them in stock so I guess I am splitting between the two now.

Thank you for your help, I greatly appreciate it!