title says it all, really. can controller be programmed to tell the display speed based on 3 hall sensors? or can white wire be added to the controller itself?
another (im)possibility. clamp magnet to spoke style speedo pickup. possible to wire that into a controller or display? or maybe with a degree and the ability to do board-level work, but us backyard a-holes can just keep dreaming...
With parameter P2 you can choose, if you want to get the speed from the rotor speed (P2=0) or from an extra speed sensor (P2=1 to 6, depending on the speed pulses per revolution)
Many geared motors have 6 pulses on the white wire integrated in the 9pin Higo motor connector.
For a direct drive you can set P2 = 0, but you have to set the value for P1 correctly, to have the proper speed shown in the display.
If you want to use an extra magnet in the spokes for the speedo, you have to solder an extra wire to the white wire solderpad on the controllers PCB...
Or have to use a KT that has an extra speed sensor input connector. But these are not waterproof normally....