Jul 3, 2026, 7:01 PM

I was curious about how the FT-891 main unit communicates with the front panel controller, the schematic shows that the RJ11 connector carries some kind of serial port. I hooked up my logic analyzer and quickly learned that Yaesu utilizes a standard UART running at 115.200 Baud, 8N1.

A Raspi connected to the RX line and a hacked up Python script helped finding out more about the protocol. It's even possible to modify data on the fly :-)

More: https://codeberg.org/Scrat/ft891-panel/ (WIP)

#amateurradio

The Yaesu FT-891 front panel connected to the main unit with an RJ11 wiretap and my cheap LWLA-1034 logic analyzer with some probes connected to the wiretap.

Holding up the FT-891 front panel controller in front of the computer monitor where the PulseView application is running. The FT-891 front panel reads 14.294.760 MHz, which can also be seen on the screen capture behind. The screen capture show the sampled wave form and the decoded UART data below as hex values. They read 0x14 0x29 0x47 0x60, which is the frequency shown on the panel, as BCD.

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