Heloo so, I send UART wavwform see pic 1 and my values are (I chect this all before I write here of course):
Uref = 1.1967V
VinA,D = 2.498V
ZX work OK, when I apply 80mV AC to Vinput - see pic 2 nice 50.5 Hz squre waves form from ZX out I get.
As I wrote SPI work well, I read all register - no problem.
