Datasheet

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NOTE
Instructions are only fetched using the AHB-Lite interface. To optimize performance, the Cortex-M0+ processor
fetches ahead of the instruction it is executing. To minimize power consumption, the fetch ahead is limited to a
maximum of 32 bits.
2.4.2.7. Single-cycle I/O port
The processor implements a single-cycle I/O port that provides high speed access to tightly-coupled peripherals, such
as general-purpose-I/O (GPIO). The port is accessible both by loads and stores from either the processor or the
debugger. You cannot execute code from the I/O port.
2.4.2.8. Power Management Unit
Each processor has its own Power Management Unit (PMU) which allows power saving by turning off clocks to parts of
the processor core. There are no separate power domains on RP2040.
The PMU runs from the processor clock which is controlled from the chip level clocks block. The PMU can control the
following clock domains within the processor:
•
A debug clock containing the processor debug resources and the rest of the DAP.
•
A system clock containing the NVIC.
•
A processor clock containing the core and associated interfaces
Control is limited to clock enable/disable. When enabled, all domains run at the same clock speed.
The PMU also interfaces with the WIC, to ensure that power-down and wake-up behaviours are transparent to software
and work with clocking and sleeping requirements. This includes SLEEP or DEEPSLEEP support as controlled in SCR
register.
2.4.2.8.1. Power Management
RP2040 ARM Cortex M0+ uses ARMv6-M which supports the use of Wait For Interrupt (WFI) and Wait For Event (WFE)
instructions as part of system power management:
WFI provides a mechanism for hardware support of entry to one or more sleep states. Hardware can suspend execution
until a wakeup event occurs.
WFE provides a mechanism for software to suspend program execution until a wakeup condition occurs with minimal or
no impact on wakeup latency. Both WFI and WFE are hint instructions that might have no effect on program execution.
Normally, they are used in software idle loops that resume program execution only after an interrupt or event of interest
occurs.
NOTE
Code using WFE and WFI must handle any spurious wakeup events caused by a debug halt or other reasons.
Refer to the SDK and ARMv6-M guide for further information.
2.4.2.8.2. Wait For Event and Send Event
RP2040 can support software-based synchronization to system events using the Send-Event (SEV) and WFE hint
instructions. Software can:
•
use the WFE instruction to indicate that it is able to suspend execution of a process or thread until an event occurs,
permitting hardware to enter a low power state.
RP2040 Datasheet
2.4. Cortex-M0+ 66