Ok guys, you got me. I gave the timing by the MCU a shot. But I did not find a efficient way to pulse it with 56KHz. How would you go about it? The "standard" way with an if statement, checkig the micros, won't work because of the "low" resolution of only 4 micros. One period is 17.86, rounding it to the 4 micros equals a frequency of 62.5KHz.
Is there a good timer library which can accomplish this easily you could recommend me?