Motorola PowerQUICC II MPC8280 Series Reference Manual page 661

Chapter 17
Baud-Rate Generators (BRGs)
The CPM contains eight independent, identical baud-rate generators (BRGs) that can be
used with the FCCs, SCCs, and SMCs. The clocks produced by the BRGs are sent to the
bank-of-clocks selection logic, where they can be routed to the controllers. In addition, the
output of a BRG can be routed to a pin to be used externally. The following is a list of
BRGs' main features:
• Eight independent and identical BRGs
• On-the-fly changes allowed
• Each BRG can be routed to one or more FCCs, SCCs, or SMCs
• A 16x divider option allows slow baud rates at high system frequencies
• Each BRG contains an autobaud support option
• Each BRG output can be routed to a pin (BRGOn)
Figure 17-1 shows a BRG.
EXTC
CLK Pin x
Clock
CLK Pin y
Source
MUX
BRGCLK
ATB
Autobaud
RXDn
Control
Figure 17-1. Baud-Rate Generator (BRG) Block Diagram
MOTOROLA
Freescale Semiconductor, Inc.
DIV 16
Divide by
1 or 16
Chapter 17. Baud-Rate Generators (BRGs)
For More Information On This Product,
Go to: www.freescale.com
CD[0–11]
Prescaler
BRGOn Clock
12-Bit Counter
1–4,096
BRGn
To Pin and/or
Bank of Clocks
17-1