083d86d251
The RP2350 boot ROM seems to randomize memory on a HW reset, including both CPU stacks where we normally stuff the "reset to bootloader" flag. Update the docs and source to remove rp2040.enableDoubleResetBootloader() on RP2350-based boards. Fixes #2606
116 lines
4.1 KiB
ReStructuredText
116 lines
4.1 KiB
ReStructuredText
RP2040 Helper Class
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===================
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Some of the core functionality of the RP2040 chip powering the Raspberry Pi
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Pico is exposed in the RP2040 class variable ``rp2040``.
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Core Internals
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--------------
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int rp2040.f_cpu()
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~~~~~~~~~~~~~~~~~~
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Returns the current frequency of the core clock. This is read at runtime,
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versus the constant ``F_CPU`` macro that is also available. This is useful
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in cases where your code changes the core clock (i.e. low power modes, etc.)
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int rp2040.cpuid()
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~~~~~~~~~~~~~~~~~~
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Returns the current core ID (0 or 1) of the executing task.
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uint32_t rp2040.getCycleCount()
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Returns a 32-bit cycle count from then the core started running. Because it
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is only 32-bits, and the Pico runs at 133MHz, this value can loop around
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in a matter of seconds.
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uint64_t rp2040.getCycleCount64()
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Returns a 64-bit cycle count from then the core started running. This value
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should never loop around in normal mode (at 133MHz it would take over 4,000
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years to overflow).
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uint32_t rp2040.hwrand32()
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~~~~~~~~~~~~~~~~~~~~~~~~~~
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Returns a 32-bit value derived from the CPU cycle counter and the ROSC
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oscillator. Because the ROSC bit is not a true random number generator, the
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values returned may not meet the most stringent random tests. **If your
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application needs absolute bulletproof random numbers, consider using
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dedicated external hardware.**
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void rp2040.reboot()
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~~~~~~~~~~~~~~~~~~~~
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Forces a hardware reboot of the Pico.
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Hardware Watchdog
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-----------------
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void rp2040.wdt_begin(uint32_t delay_ms)
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Enables the hardware watchdog timer with a delay value of delay_ms
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milliseconds. Note that on the RP2040, once this function has called, the
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hardware watchdog can _not_ be disabled.
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The maximum ``delay_ms`` allowed in this call is ``8300``, corresponding
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to 8.3 seconds. Any higher values will be truncated by the hardware.
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void rp2040.wdt_reset()
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~~~~~~~~~~~~~~~~~~~~~~~
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Reloads the watchdog's counter with the amount of time set by wdt_begin.
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RP2040::resetReason_t rp2040.getResetReason()
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Returns the reason for the last reset, defined in enum ``RP2040::resetReason_t``.
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See example ```ResetReason``` for some details.
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Memory Information
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------------------
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int rp2040.getFreeHeap()
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~~~~~~~~~~~~~~~~~~~~~~~~
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Returns the number of bytes free for heap allocation (i.e. malloc, new). Note
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that because there is some overhead, and there may be heap fragmentation,
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this number is an *upper bound* and you generally will only be able to allocate
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less than this returned number.
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int rp2040.getUsedHeap()
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~~~~~~~~~~~~~~~~~~~~~~~~
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Returns the number of bytes allocated out of the heap.
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int rp2040.getTotalHeap()
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~~~~~~~~~~~~~~~~~~~~~~~~~
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Returns the total heap that was available to this program at compile time (i.e.
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the Pico RAM size minus things like the ``.data`` and ``.bss`` sections and other
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overhead).
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Hardware Identification
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-----------------------
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bool rp2040.isPicoW()
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~~~~~~~~~~~~~~~~~~~~~
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Returns the core's best guess if this code is running on a Raspberry Pi Pico W.
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This would let you, possibly, use the same UF2 for Pico and PicoW by simply not
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doing any WiFi calls.
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Bootloader
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----------
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void rp2040.enableDoubleResetBootloader() (Pico/RP2040 only)
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Add a call anywhere in the sketch to ``rp2040.enableDoubleResetBootloader()`` and
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the core will check for a double-tap on reset, and if found will start the USB
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bootloader.
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void rp2040.rebootToBootloader()
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Will reboot the RP2040 into USB UF2 upload mode.
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DMA-based MEMCPY
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----------------
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The onboard DMA engines can copy 4-byte aligned quantities faster than the CPU.
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void \*rp2040.memcpyDMA(void \*dest, const void \*src, size_t count);
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Uses a DMA engine to transfer data from src to dest in 4-byte chunks without CPU
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intervention. If any arguments are not 4-byte aligned, or if the count is not a
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multiple of 4, then it will fall back to CPU-managed memcpy.
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