I am trying to interface a WRT54G serial port directly with an arduino pro micro's hardware UART by connecting RX to TX and TX to RX between the devices.
I have a simple code running on the arduino which outputs a character on the hardware UART in every second. If I check it with the scope or multimeter before the converter I see the jumps up to about 4.7V which is ok. On the other side of the converter all I see is some low voltage noise coming out of the pin (LV 3.3) side.
1, Do these TTL converters needed to be feed from both the 3.3V and 5V side to work correctly?
2, Couldn't this setup be done by using 1 or 2 resistors on both RX/TX wires? I assume the resistor would only be needed on the TX line of the arduino not to overload the WRTG when it sends data. However the 3.3V might not high enough to trigger an input on the arduino's hardware uart when data coming in
What's weird in this setup that I have a working older WRTG router which is directly connected to an arduino nano (running from 5V) and no problem with the communication between them.