I'm primarily a SW developer who dabbles with electronics. I needs to interface my SoC's HW full-duplex UART with an SDI-12 compliant sensor, without burning either of them and hopefully without wasting too much power. The following constraints are given:
- Full-duplex side operates on 3.3V, normal polarity (i.e. logic LOW is 0V and logic HIGH is 3.3V), has separate TX (output) and RX (input) pins.
- Half-duplex side operates anywhere between 3.5V-5.5V, inverted polarity, has a single TX/RX pin
- There vast majority of the time the line will be silent (i.e. the wire connecting to sensors TX/RX pin will be at 0V
- The wire leading to a sensors TX/RX pin might be long (just in case any funkiness of high parasitic inductance or something should change my design).
The circuit I drafted quickly:
In particular I'm curious if you had any comments about the choice of particular components and their values.