I tried to build a remote serial console in my WAVLINK AC1200 (WL-WN572HG3) with an ESP8266 (esplink). The main idea is to update (development) the device while its on the antenna pole (several meters out of reach).
After I soldered the ESP8266 I found the router does not give any output. I think I found the problem when I compared the PCB with old pictures.
It looks like there was some pulldown resistor and I removed it by accident. This is the part I don't understand. Why would there be a pulldown resistor when the switch (if pressed) pulls the line down to GND anyway? I would agree if it would be a pullup resistor.
Does somebody have a better understanding of the situation?
Based on the logic and the vague picture you provided, most likely it was a capacitor and in any case it shouldn't cause your troubles with the serial console.
Yeah I thought of this too. But I am still unsure because there is no feedback from the router. I will futher investigate this.
After some investigation I found the reset does not work anymore but there is some valid output on the serial line (uboot).
It looks like the reset line becomes "high" after a few seconds into the power up. I still cant see how this reset switch would work as the missing part does definitely lead to the current malfunction of the reset switch. If it would be a "soft" pull down resistor and the switch does a "hard" pull to low I could explain something. I am a bit confused by this.