02620c2236
This is the minimum C interface to allow a modem driver to be built in Python. Interface is simple, with the intention that the micropython-lib driver is the main (only) consumer of it. Signed-off-by: Angus Gratton <angus@redyak.com.au>
141 lines
4.3 KiB
ReStructuredText
141 lines
4.3 KiB
ReStructuredText
.. currentmodule:: stm
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:mod:`stm` --- functionality specific to STM32 MCUs
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===================================================
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.. module:: stm
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:synopsis: functionality specific to STM32 MCUs
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This module provides functionality specific to STM32 microcontrollers, including
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direct access to peripheral registers.
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Memory access
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-------------
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The module exposes three objects used for raw memory access.
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.. data:: mem8
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Read/write 8 bits of memory.
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.. data:: mem16
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Read/write 16 bits of memory.
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.. data:: mem32
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Read/write 32 bits of memory.
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Use subscript notation ``[...]`` to index these objects with the address of
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interest.
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These memory objects can be used in combination with the peripheral register
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constants to read and write registers of the MCU hardware peripherals, as well
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as all other areas of address space.
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Peripheral register constants
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-----------------------------
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The module defines constants for registers which are generated from CMSIS header
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files, and the constants available depend on the microcontroller series that is
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being compiled for. Examples of some constants include:
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.. data:: GPIOA
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Base address of the GPIOA peripheral.
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.. data:: GPIOB
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Base address of the GPIOB peripheral.
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.. data:: GPIO_BSRR
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Offset of the GPIO bit set/reset register.
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.. data:: GPIO_IDR
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Offset of the GPIO input data register.
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.. data:: GPIO_ODR
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Offset of the GPIO output data register.
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Constants that are named after a peripheral, like ``GPIOA``, are the absolute
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address of that peripheral. Constants that have a prefix which is the name of a
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peripheral, like ``GPIO_BSRR``, are relative offsets of the register. Accessing
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peripheral registers requires adding the absolute base address of the peripheral
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and the relative register offset. For example ``GPIOA + GPIO_BSRR`` is the
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full, absolute address of the ``GPIOA->BSRR`` register.
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Example use:
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.. code-block:: python3
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# set PA2 high
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stm.mem32[stm.GPIOA + stm.GPIO_BSRR] = 1 << 2
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# read PA3
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value = (stm.mem32[stm.GPIOA + stm.GPIO_IDR] >> 3) & 1
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Functions specific to STM32WBxx MCUs
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------------------------------------
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These functions are available on STM32WBxx microcontrollers, and interact with
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the second CPU, the RF core.
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.. function:: rfcore_status()
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Returns the status of the second CPU as an integer (the first word of device
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info table).
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.. function:: rfcore_fw_version(id)
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Get the version of the firmware running on the second CPU. Pass in 0 for
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*id* to get the FUS version, and 1 to get the WS version.
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Returns a 5-tuple with the full version number.
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.. function:: rfcore_sys_hci(ogf, ocf, data, timeout_ms=0)
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Execute a HCI command on the SYS channel. The execution is synchronous.
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Returns a bytes object with the result of the SYS command.
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Functions specific to STM32WLxx MCUs
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------------------------------------
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These functions are available on STM32WLxx microcontrollers, and interact with
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the integrated "SUBGHZ" radio modem peripheral.
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.. function:: subghz_cs(level)
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Sets the internal SPI CS pin attached to the radio peripheral. The ``level``
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argument is active-low: a truthy value means "CS pin high" and de-asserts the
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signal, a falsey value means "CS pin low" and asserts the signal.
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The internal-only SPI bus corresponding to this CS signal can be instantiated
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using :ref:`machine.SPI()<machine.SPI>` ``id`` value ``"SUBGHZ"``.
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.. function:: subghz_irq(handler)
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Sets the internal SUBGHZ radio interrupt handler to the provided
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function. The handler function is called as a "hard" interrupt in response to
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radio peripheral interrupts. See :ref:`isr_rules` for more information about
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interrupt handlers in MicroPython.
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Calling this function with the handler argument set to None disables the IRQ.
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Due to a hardware limitation, each time this IRQ fires MicroPython disables
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it before calling the handler. In order to receive another interrupt, Python
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code should call ``subghz_irq()`` to set the handler again. This has the side
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effect of re-enabling the IRQ.
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.. function:: subghz_is_busy()
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Return a ``bool`` corresponding to the internal "RFBUSYS" signal from the
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radio peripheral. Before sending a new command to the radio over SPI then
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this function should be polled until it returns ``False``, to confirm the
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busy signal is de-asserted.
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