Posted on December 19, 2014 at 17:50How do you configure the baud rate generator? What's your HSE oscillator? You need a frequency high enough to divide down to your target. Using HSI at that high a rate will likely create some jitter, making the connection unreliable. Be sure the baud rate at both ends is exact, any deviation, even with async, is going to cause the start bit to drift. A 1% error is fine at 9600, inoperable at 960K.
What baud rate are you trying for? Is your program fast enough to handle that rate? If you are using per character interrupts that's <1usec service time, not gonna have much CPU left for anything else.
What's the physical interface? RS-232 transceivers don't work at those kinds of speeds. The slew rate turns your cable into a very good RF generator with nice sharp edges in the medium wave band. Your neighbors with a radio will really appreciate your broadband static transmitter. Look at RS-485 or for short distance a TTL line driver. Current loop won't work at those speeds either.
If you really need multi-megabit data rates you'd be better off looking at USB or Ethernet. A serial USART is the wrong tool for the job.
Jack Peacock
