kopia lustrzana https://github.com/micropython/micropython
132 wiersze
4.5 KiB
ReStructuredText
132 wiersze
4.5 KiB
ReStructuredText
.. currentmodule:: rp2
|
|
.. _rp2.StateMachine:
|
|
|
|
class StateMachine -- access to the RP2040's programmable I/O interface
|
|
=======================================================================
|
|
|
|
The :class:`StateMachine` class gives access to the RP2040's PIO (programmable
|
|
I/O) interface.
|
|
|
|
For assembling PIO programs, see :func:`rp2.asm_pio`.
|
|
|
|
|
|
Constructors
|
|
------------
|
|
|
|
.. class:: StateMachine(id, [program, ...])
|
|
|
|
Get the state machine numbered *id*. The RP2040 has two identical PIO
|
|
instances, each with 4 state machines: so there are 8 state machines in
|
|
total, numbered 0 to 7.
|
|
|
|
Optionally initialize it with the given program *program*: see
|
|
`StateMachine.init`.
|
|
|
|
|
|
Methods
|
|
-------
|
|
|
|
.. method:: StateMachine.init(program, freq=-1, *, in_base=None, out_base=None, set_base=None, jmp_pin=None, sideset_base=None, in_shiftdir=None, out_shiftdir=None, push_thresh=None, pull_thresh=None)
|
|
|
|
Configure the state machine instance to run the given *program*.
|
|
|
|
The program is added to the instruction memory of this PIO instance. If the
|
|
instruction memory already contains this program, then its offset is
|
|
re-used so as to save on instruction memory.
|
|
|
|
- *freq* is the frequency in Hz to run the state machine at. Defaults to
|
|
the system clock frequency.
|
|
|
|
The clock divider is computed as ``system clock frequency / freq``, so
|
|
there can be slight rounding errors.
|
|
|
|
The minimum possible clock divider is one 65536th of the system clock: so
|
|
at the default system clock frequency of 125MHz, the minimum value of
|
|
*freq* is ``1908``. To run state machines at slower frequencies, you'll
|
|
need to reduce the system clock speed with `machine.freq()`.
|
|
- *in_base* is the first pin to use for ``in()`` instructions.
|
|
- *out_base* is the first pin to use for ``out()`` instructions.
|
|
- *set_base* is the first pin to use for ``set()`` instructions.
|
|
- *jmp_pin* is the first pin to use for ``jmp(pin, ...)`` instructions.
|
|
- *sideset_base* is the first pin to use for side-setting.
|
|
- *in_shiftdir* is the direction the ISR will shift, either
|
|
`PIO.SHIFT_LEFT` or `PIO.SHIFT_RIGHT`.
|
|
- *out_shiftdir* is the direction the OSR will shift, either
|
|
`PIO.SHIFT_LEFT` or `PIO.SHIFT_RIGHT`.
|
|
- *push_thresh* is the threshold in bits before auto-push or conditional
|
|
re-pushing is triggered.
|
|
- *pull_thresh* is the threshold in bits before auto-pull or conditional
|
|
re-pulling is triggered.
|
|
|
|
.. method:: StateMachine.active([value])
|
|
|
|
Gets or sets whether the state machine is currently running.
|
|
|
|
>>> sm.active()
|
|
True
|
|
>>> sm.active(0)
|
|
False
|
|
|
|
.. method:: StateMachine.restart()
|
|
|
|
Restarts the state machine and jumps to the beginning of the program.
|
|
|
|
This method clears the state machine's internal state using the RP2040's
|
|
``SM_RESTART`` register. This includes:
|
|
|
|
- input and output shift counters
|
|
- the contents of the input shift register
|
|
- the delay counter
|
|
- the waiting-on-IRQ state
|
|
- a stalled instruction run using `StateMachine.exec()`
|
|
|
|
.. method:: StateMachine.exec(instr)
|
|
|
|
Execute a single PIO instruction. Uses `asm_pio_encode` to encode the
|
|
instruction from the given string *instr*.
|
|
|
|
>>> sm.exec("set(0, 1)")
|
|
|
|
.. method:: StateMachine.get(buf=None, shift=0)
|
|
|
|
Pull a word from the state machine's RX FIFO.
|
|
|
|
If the FIFO is empty, it blocks until data arrives (i.e. the state machine
|
|
pushes a word).
|
|
|
|
The value is shifted right by *shift* bits before returning, i.e. the
|
|
return value is ``word >> shift``.
|
|
|
|
.. method:: StateMachine.put(value, shift=0)
|
|
|
|
Push a word onto the state machine's TX FIFO.
|
|
|
|
If the FIFO is full, it blocks until there is space (i.e. the state machine
|
|
pulls a word).
|
|
|
|
The value is first shifted left by *shift* bits, i.e. the state machine
|
|
receives ``value << shift``.
|
|
|
|
.. method:: StateMachine.rx_fifo()
|
|
|
|
Returns the number of words in the state machine's RX FIFO. A value of 0
|
|
indicates the FIFO is empty.
|
|
|
|
Useful for checking if data is waiting to be read, before calling
|
|
`StateMachine.get()`.
|
|
|
|
.. method:: StateMachine.tx_fifo()
|
|
|
|
Returns the number of words in the state machine's TX FIFO. A value of 0
|
|
indicates the FIFO is empty.
|
|
|
|
Useful for checking if there is space to push another word using
|
|
`StateMachine.put()`.
|
|
|
|
.. method:: StateMachine.irq(handler=None, trigger=0|1, hard=False)
|
|
|
|
Returns the IRQ object for the given StateMachine.
|
|
|
|
Optionally configure it.
|
|
|