FPGA Registers
EPU-4562 Programmer’s Reference Manual
40
UARTMODE2 – UART MODE REGISTER #2
Standard software (the BIOS and the operating system) assumes the baud-rate clock is
1.8432 MHz and programs the divisors accordingly; however, a faster oscillator is needed for
baud rates higher than 115,200.
The FAST_MODE bit in this register shifts the divisor by 4 bits (multiply by 16) so that the
legacy baud rate comes out correctly for the 16x UART clock. This bit must be set to use rates
above 115,200 and may require custom software.
Reset type is Platform.
Note:
The values shown are for the default BIOS configuration.
Table 48: UARTMODE2 – UART MODE Register #2
Bits
Identifier
Access
Default
Description
7-1
Reserved
RO
0000000
Reserved. Writes are ignored; reads always return 0.
0
FAST_MODE
R/W
0
Sets how the baud-rate divisor for the 16550 UARTs are
interpreted (applies to all ports):
0 – Divisor is multiplied by 16 (legacy mode for 1.8432 MHz
clock)
1 – Divisor is not modified (fast mode for 16x 1.8432 MHz clock)
Note:
This must be set to ‘1’ to use baud rates above 115,200.