See: https://hackaday.com/blog/?s=Raspberry+Pi+HAT+for+IEEE1588 I got a quote; a 3 port hat is 400 Euro. You'll have to decide. Comments very welcome. Don ------------ The whole world is a straight man. ---------------------- Dr. Don Latham AJ7LL PO Box 404, Frenchtown, MT, 59834 VOX: 406-626-4304