at90pwm81-16se ATMEL Corporation, at90pwm81-16se Datasheet - Page 42

• Manufacturer Part Number: at90pwm81-16se
• Description: 8-bit Avr Microcontroller With 8k Bytes In- System Programmable Flash
• Manufacturer: ATMEL Corporation

6.5.6
42
AT90PWM81
Clock Selection Register - CLKSELR
• Bits 3:0 – CLKC3:0: Clock Control Bits 3 - 0
These bits define the command to provide to the ‘Clock Switch’ module. The special write procedure must
be followed to change the CLKC bits
41.).
Interrupts should be disabled when setting CLKCSR register in order not to disturb the procedure.
Table 6-12.
• Bit 7– Res: Reserved Bit
This bit is reserved bit in the AT90PWM81 and will always read as zero.
• Bit 6 – COUT: Clock Out
The COUT bit is initialized with CKOUT Fuse bit.
The COUT bit is only used in case of ‘CKOUT’ command. Refer to
on page 34
In case of ‘Recover System Clock Source’ command, COUT it is not affected (no recovering of this
setting).
• Bits 5:4 – CSUT1:0: Clock Start-up Time
CSUT bits are initialized with the values of SUT Fuse bits.
In case of ‘Enable/Disable Clock Source’ command, CSUT field provides the code of the clock start-up
time. Refer to subdivisions of
In case of ‘Recover System Clock Source’ command, CSUT field is not affected (no recovering of SUT
code).
• Bits 3:0 – CSEL3:0: Clock Source Select
Bit
Read/Write
Initial Value
Clock Command
No command
Disable clock source
Enable clock source
Request for clock
Clock source switch
Recover system clock source code
CKOUT command
No command
1.
2.
Write the Clock Control Change Enable (CLKCCE) bit to one and all other bits in
CLKCSR to zero.
Within 4 cycles, write the desired value to CLKCSR register while clearing CLKCCE bit.
for using.
Clock command list.
R
7
0
availability
-
CKOUT
COUT
R/W
fuse
6
Section 6.2 ”Clock Sources” on page 28
CSUT1
R/W
5
(See ”Bit 7 – CLKCCE: Clock Control Change Enable” on page
SUT1..0
fuses
CSUT0
R/W
4
CSEL3
R/W
3
CSEL2
R/W
2
Section 6.2.7 ”Clock Output Buffer”
CKSEL3..0
for code of clock start-up times.
fuses
CSEL1
R/W
1
CSEL0
R/W
0
CLKC3..0
7734M–AVR–03/10
0010
0000
0001
0011
0100
0101
0111
1xxx
CLKSELR
b
b
b
b
b
b
b
b