I'm a hobbyist. I ran across a peculiar TTL-level UART, the 74LVC8153 (PDF). I'd like to connect one or more of these to a laptop using a USB-to-serial device, and the most widely used USB-to-serial seems to be the FTDI232.
Difficulty...the 74LVC8153 part requires peculiar framing: 2 start bits (low, high), 7 data bits, and 1 stop bit. The data and stop bits are fine, but "two start bits" is a different story. I've looked at the data sheets I could find for the FTDI232, its device drivers, traditional Linux/MacOS terminal drivers, the stty command, etc. There seems to be no direct support for 2 start bits anywhere.
Does this kill the idea or is there some way around it? For example I found this FTDI232 trick for setting nonstandard baud rates, but nothing about framing. Or is there some other USB-to-serial device that supports more framing alternatives, or a sort of "raw mode" where I could just send it bits that control the transmit line?