Improved baud rate settings formula

Author: agdl

cores/arduino/UART.cpp

@@ -197,7 +197,7 @@ void UartClass::begin(unsigned long baud, uint16_t config)
 
         int8_t sigrow_val = SIGROW.OSC16ERR5V;
         baud_setting *= (1024 + sigrow_val);
-        baud_setting /= 1024;
+        baud_setting /= (1024 - sigrow_val);
 
         // assign the baud_setting, a.k.a. BAUD (USART Baud Rate Register)
         (*_hwserial_module).BAUD = (int16_t) baud_setting;