93
8331B–AVR–03/12
Atmel AVR XMEGA AU
• Bit 6:2 – PSADIV[4:0]: Prescaler A Division Factor
These bits define the division ratio of the clock prescaler A according to
. These bits
can be written at run-time to change the frequency of the Clk
PER4
clock relative to the system
clock, Clk
SYS
.
• Bit 1:0 – PSBCDIV: Prescaler B and C Division Factors
These bits define the division ratio of the clock prescalers B and C according to
. Pres-
caler B will set the clock frequency for the Clk
PER2
clock relative to the Clk
PER4
clock. Prescaler C
will set the clock frequency for the Clk
PER
and Clk
CPU
clocks relative to the Clk
PER2
clock. Refer
fore more details.
Table 7-2.
Prescaler A division factor.
PSADIV[4:0]
Group Configuration
Description
00000
1
No division
00001
2
Divide by 2
00011
4
Divide by 4
00101
8
Divide by 8
00111
16
Divide by 16
01001
32
Divide by 32
01011
64
Divide by 64
01101
128
Divide by 128
01111
256
Divide by 256
10001
512
Divide by 512
10101
Reserved
10111
Reserved
11001
Reserved
11011
Reserved
11101
Reserved
11111
Reserved
Table 7-3.
Prescaler B and C division factors.
PSBCDIV[1:0]
Group Configuration
Prescaler B division
Prescaler C division
00
1_1
No division
No division
01
1_2
No division
Divide by 2
10
4_1
Divide by 4
No division
11
2_2
Divide by 2
Divide by 2