On 21/07/2021 19:36, Joe Subich, W4TV wrote:
On 2021-07-21 1:46 PM, g4wjs wrote:
you are confusing USB ports and USB endpoints. I doubt there is a USB
hub in the FT-991A, it is more likely a single device with multiple
endpoints for audio in, audio out, and a pair of serial ports.
I do not know of any device that implements a USB CODEC and dual port
UART in the same chip. Since Yaesu use the Sierra dual port USB to
Serial Bridge, I suspect they are also using a standard Burr Brown (TI)
USB Codec like Icom, Kenwood and Elecraft (K3S). With the Burr-Brown
CODEC and Sierra dual port USB to Serial Bridge, one would need a USB
Hub with at least two ports (but four port hubs are generally the same
it would seem so, the FT991A uses a USB hub controller (Microchip USB2512B). It seems modern rigs are no longer USB devices but are USB multi-function devices.