Might be some YouTube videos on mitered log trusses. I prefer the housed joint since it hides much of the shrinkage effects. You basically cut a shoulder square to the tenon on one round piece and then cut out a slot for the tenon in a piece of plywood. Then put the plywood over the tenon down to the shoulder and trace the circumference of the tenoned log on the ply and cut it out. Take this template over to the piece to be mortised that has been leveled, and screw it over the roughed out mortise location, shimming and wedging it to keep it level. Plumb down from the sides of the template with a torpedo to create the profile of the tenoned log on the mortised piece. Then drill out the housing plumb with a 1-2" self-feed bit until the entire housing table is level and below the surface of the log. Use the datum of this table to figure out where to cut the tenoned piece to length. Drill the mortise deeper as required to take the tenon. It's like double scribing, where you insert a waney tenoned piece into a mortise partway and then scribe the waney shoulder to finish it.
It's pretty hard to describe but maybe you can find some other videos online, as I learned this from some Japanese carpenters. This is one of the techniques we teach at Heartwood, and I should do a video myself, one of these days....