Motorola PowerQUICC II MPC8280 Series Reference Manual page 663

0
Field
Reset
R/W
Addr 0x (BRGC1), 0x119F4 (BRGC2), 0x119F8 (BRGC3), 0x119FC (BRGC4),
0x115F0 (BRGC5), 0x115F4 (BRGC6), 0x1115F8 (BRGC7), 0x115FC (BRGC8)
16 17 18
Field EXTC ATB
Reset
R/W
Addr 0x119F22 (BRGC1), 0x119F6 (BRGC2), 0x119FA (BRGC3), 0x119FE (BRGC4),
0x115F2 (BRGC5), 0x115F6 (BRGC6), 0x115FA (BRGC7), 0x115FE (BRGC8)
Figure 17-2. Baud-Rate Generator Configuration Registers (BRGCx)
Table 17-1 describes the BRGCx fields.
Bits Name
0–13 — Reserved, should be cleared.
14 RST Reset BRG. Performs a software reset of the BRG identical to that of an external reset. A reset
disables the BRG and drives BRGO high. This is externally visible only if BRGO is connected to the
corresponding parallel I/O pin.
0 Enable the BRG.
1 Reset the BRG (software reset).
15 EN Enable BRG count. Used to dynamically stop the BRG from counting—useful for low-power modes.
0 Stop all clocks to the BRG.
1 Enable clocks to the BRG.
16–17 EXTC External clock source. Selects the BRG input clock. See Table 17-2..
00 The BRG input clock comes from the BRGCLK (internal clock generated from the CPM clock);
see Section 10.4, "System Clock Control Register (SCCR)."
01 If BRG1, 2, 5, 6: The BRG input clock comes from the CLK3 pin.
If BRG3, 4, 7, 8: The BRG input clock comes from the CLK9 pin
10 If BRG1, 2, 5, 6: The BRG input clock comes from the CLK5 pin.
If BRG3, 4, 7, 8: The BRG input clock comes from the CLK15 pin
11 Reserved.
18 ATB Autobaud. Selects autobaud operation of the BRG on the corresponding RXD. ATB must remain
zero until the SCC receives the three Rx clocks. Then the user must set ATB to obtain the correct
baud rate. After the baud rate is obtained and locked, it is indicated by setting AB in the UART event
register.
0 Normal operation of the BRG.
1 When RXD goes low, the BRG determines the length of the start bit and synchronizes the BRG
to the actual baud rate.
MOTOROLA
Freescale Semiconductor, Inc.
—
0000_0000_0000_0000
19
0000_0000_0000_0000
Table 17-1. BRGCx Field Descriptions
Chapter 17. Baud-Rate Generators (BRGs)
For More Information On This Product,
Go to: www.freescale.com
BRG Configuration Registers 1–8 (BRGCx)
R/W
CD
R/W
Description
13 14 15
RST EN
30 31
DIV16
17-3