I have a single-line transmission device, I use the oscilloscope to check the waveform Always keep high potential (12V) and low potential (0V), change to logic analyzer test and find that it can be decoded by UART, baud rate 115200 A little search to know that this is a single-line half-duplex working method I want to use the computer's COM port to interact with it now, but my UARTtoUSB device only supports 5V or 3.3V level, what level conversion chip or circuit can convert 12V level to 3.3V? Single line half-duplex Does the worker's working method only need to short the TX and RX and then connect the signal?
You can use the MAX3182 IC. It can take anything between +/-25V and convert it to either 3V3 or 5V. Check out the datasheet and decide which one suits you best. Looking at the waveform, it looks idle high, which is the case for TTL-UART, so you should use a non-inverting configuration (i.e. MAX3182 or MAX3183). Among the two, one supports a "not output enable" input and the other - a "not invalid" output, so decide for yourself if you need either of the two functions.