:exclamation: This page is outdated

Rotorflight Wiki is replaced by www.rotorflight.org.

---

The F4 Processor Needs Uninverted Signals

However, SBUS, SmartPort and Fport are inverted signals. The F4 processor can't invert input signals, so it needs an uninverted signal. In order to connect an SBUS signal, most F4 boards also have an SBUS input. This is usually an inverted RX input. For example, the JHEMCU GHF13AIO has an SBUS input pad, which is actually an inverted RX2.

If you want to connect an SBUS receiver to another UART, e.g. RX1, then you need to invert that SBUS signal to get an uninverted signal. For this you might need an external inverter, or maybe you can get an uninverted signal from the receiver itself. Then you can connect that uninverted signal to an RX pad. In case of the GHF13AIO you can connect the uninverted SBUS signal to RX1. This frees TX2 which you can then use for something else, e.g. OpenLog/OpenLager.

Uninverted SBUS / SmartPort signals:

• On FrSky receivers
• Simple external inverter
• External SmartPort Inverter