From SpecNext official Wiki
|Short desc.||Reads data from serial port, write sets the baudrate|
|Bit Mask||%0001 0100 0011 1011|
Read a byte from the receive buffer. If the buffer is empty, 0 is returned.
Writes the lower 14-bits of the UART's prescalar value that determines baud rate
- If bit 7 = 1
- bits 6:0 = upper 7-bits of the 14-bit prescalar value
- If bit 7 = 0
- bits 6:0 = lower 7-bits of the 14-bit prescalar value
The UART's baud rate is determined by the prescalar according to this formula:
- prescalar = Fsys / baudrate ; Fsys = system clock from Video Timing Register ($11)
Eg: If the system is HDMI, nextreg 0x11 indicates that Fsys = 27000000. The prescalar for a baud rate of 115200 is 27000000 / 115200 = 234.