
EZ-USB FX2 Technical Reference Manual
Page 14-14 EZ-USB FX2 Technical Reference Manual v2.1
14.3.2 High-Speed Baud Rate Generator
The FX2 incorporates a high-speed baud rate generator which can provide 115.2K and 230.4K
baud rates for either or both serial ports, regardless of the FX2’s internal clock frequency (12, 24,
or 48 MHz).
The high-speed baud rate generator is enabled for Serial Port 0 by setting UART230.0 to 1; it’s
enabled for Serial Port 1 by setting UART230.1 to 1.
When enabled, the high-speed baud rate generator defaults to 115.2K baud. To select 230.4K
baud for Serial Port 0, set SMOD0 (PCON.7) to 1; for Serial Port 1, set SMOD1 (EICON.7) to 1.
When the High-Speed Baud Rate Generator is enabled for either serial port, neither port may use
Timer 1 as its baud-clock source. Therefore, the allowable combinations of baud-clock sources for
Modes 1 and 3 are:
Table 14-9. UART230 Register — Address 0xE608
Bit Function
UART230.7:2 Reserved
UART230.1 230UART1 - Enable high-speed baud rate generator for serial port 1. When 230UART1
= 1, a 115.2K baud (if SMOD1 = 0) or 230.4K baud (if SMOD1 = 1) clock is provided to
serial port 1. When 230UART1 = 0, serial port 1’s baud clock is provided by one of the
sources shown in Tabl e14-7.
UART230.0 230UART0 - Enable high-speed baud rate generator for serial port 0. When 230UART0
= 1, a 115.2K baud (if SMOD0 = 0) or 230.4K baud (if SMOD0 = 1) clock is provided to
serial port 0. When 230UART1 = 0, serial port 0’s baud clock is provided by one of the
sources shown in Tabl e14-7.
Table 14-10. Allowable Baud-Clock Combinations for Modes 1 and 3
Port 0 Port 1
Timer 1 Timer 1
Timer 2 Timer 1
Timer 2 High-Speed Baud Rate Generator
High-Speed Baud Rate Generator High-Speed Baud Rate Generator
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