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Document 38-08035 Rev. *K Page 26 of 83
10.2 CPU Clock During Sleep Mode
When the CPU enters sleep mode the CPUCLK Select (Bit [0], Table 10-3 on page 22) is forced to the Internal Oscillator, and the
oscillator is stopped. When the CPU comes out of sleep mode it runs on the internal oscillator. The internal oscillator recovery time is
three clock cycles of the Internal 32 kHz Low power Oscillator.
If the system requires the CPU to run off the external clock after awaking from sleep mode, the firmware must switch the clock source
for the CPU.
Figure 10-3. Timer Capture Block Diagram
16-bit counter
Configuration Status
and Control
Prescale Mux
Capture Registers
Interrupt Controller
1ms
timer
Overflow
Interrupt
Captimer Clock
System Clock
Capture0 Int Capture1 Int
Table 10-7. Clock IO Config (CLKIOCR) [0x32] [R/W]
Bit # 7 6 5 4 3 2 1 0
Field Reserved CLKOUT Select
Read/Write – – –---R/W R/W
Default 0 0 00000 0
Bit [7:2]: Reserved
Bit [1:0]: CLKOUT Select
0 0 = Internal 24 MHz Oscillator
0 1 = External clock – external clock at CLKIN (P0.0)
1 0 = Internal 32 kHz low power oscillator
1 1 = CPUCLK
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