CMS32L051 User Manual |Chapter 20 Standby Function
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20.3.2 Release of deep sleep mode
Deep sleep mode can be released in the following two ways.
(1) Release through an unmasked interrupt request
If an unmasked interrupt request occurs, deep sleep mode is released. After the oscillation settling time, the
deep sleep mode is released and the CPU begins to process the interrupt service program.
Figure 20-3 Release deep sleep mode by interrupting requests
standby release signal
CPU status normal operation deep sleep state deep sleep state release preparation time
note1
deep sleep state released, execute next instruction
note1
Note1
Note 1 Standby release signal: For more information on standby release signals, refer to Figure 20-1
Basic Structure of the Interrupt Function.
2. Deep sleep state release preparation time:
When the CPU clock is a high-speed internal oscillating clock or an external clock input before
entering deep sleep mode: at least 20us
When the CPU clock is a high-speed system clock (X1 oscillation) before entering deep sleep
mode: at least 20us with a longer oscillation settling time (set via OSTS).
3. Wait: From CPU The IRQ is valid until the interrupt service program is started, which takes 14
clocks.
Note: 1. Before entering sleep mode, only the mask bit corresponding to the interrupt that is expected to be
used to release sleep mode should be cleared.
2. When the CPU is running at a high-speed system clock (X1 oscillation) and to reduce the
oscillation settling time after the deep sleep mode is released, the CPU clock must be temporarily
switched to a high-speed internal oscillator clock before executing WFI instructions.
Note The oscillation accuracy of the high-speed internal oscillator clock is stable and waits to change due to temperature
conditions and during deep sleep mode.
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