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rp2040.rst

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RP2040 Helper Class

Some of the core functionality of the RP2040 chip powering the Raspberry Pi Pico is exposed in the RP2040 class variable rp2040.

Core Internals

int rp2040.f_cpu()

Returns the current frequency of the core clock. This is read at runtime, versus the constant F_CPU macro that is also available. This is useful in cases where your code changes the core clock (i.e. low power modes, etc.)

int rp2040.cpuid()

Returns the current core ID (0 or 1) of the executing task.

uint32_t rp2040.getCycleCount()

Returns a 32-bit cycle count from then the core started running. Because it is only 32-bits, and the Pico runs at 133MHz, this value can loop around in a matter of seconds.

uint64_t rp2040.getCycleCount64()

Returns a 64-bit cycle count from then the core started running. This value should never loop around in normal mode (at 133MHz it would take over 4,000 years to overflow).

uint32_t rp2040.hwrand32()

Returns a 32-bit value derived from the CPU cycle counter and the ROSC oscillator. Because the ROSC bit is not a true random number generator, the values returned may not meet the most stringent random tests. If your application needs absolute bulletproof random numbers, consider using dedicated external hardware.

void rp2040.reboot()

Forces a hardware reboot of the Pico.

Hardware Watchdog

void rp2040.wdt_begin(uint32_t delay_ms)

Enables the hardware watchdog timer with a delay value of delay_ms milliseconds. Note that on the RP2040, once this function has called, the hardware watchdog can _not_ be disabled.

The maximum delay_ms allowed in this call is 8300, corresponding to 8.3 seconds. Any higher values will be truncated by the hardware.

void rp2040.wdt_reset()

Reloads the watchdog's counter with the amount of time set by wdt_begin.

RP2040::resetReason_t rp2040.getResetReason()

Returns the reason for the last reset, defined in enum RP2040::resetReason_t. See example `ResetReason` for some details.

Memory Information

int rp2040.getFreeHeap()

Returns the number of bytes free for heap allocation (i.e. malloc, new). Note that because there is some overhead, and there may be heap fragmentation, this number is an upper bound and you generally will only be able to allocate less than this returned number.

int rp2040.getUsedHeap()

Returns the number of bytes allocated out of the heap.

int rp2040.getTotalHeap()

Returns the total heap that was available to this program at compile time (i.e. the Pico RAM size minus things like the .data and .bss sections and other overhead).

Hardware Identification

bool rp2040.isPicoW()

Returns the core's best guess if this code is running on a Raspberry Pi Pico W. This would let you, possibly, use the same UF2 for Pico and PicoW by simply not doing any WiFi calls.

Bootloader

void rp2040.enableDoubleResetBootloader() (Pico/RP2040 only)

Add a call anywhere in the sketch to rp2040.enableDoubleResetBootloader() and the core will check for a double-tap on reset, and if found will start the USB bootloader.

void rp2040.rebootToBootloader()

Will reboot the RP2040 into USB UF2 upload mode.

DMA-based MEMCPY

The onboard DMA engines can copy 4-byte aligned quantities faster than the CPU.

void *rp2040.memcpyDMA(void *dest, const void *src, size_t count);

Uses a DMA engine to transfer data from src to dest in 4-byte chunks without CPU intervention. If any arguments are not 4-byte aligned, or if the count is not a multiple of 4, then it will fall back to CPU-managed memcpy.