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Update esp32.RMT module to the new API #16293

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cfdd448
ports/esp32: Update RMT module to use the new RMT API.
elvis-epx Nov 22, 2024
826eab5
ports/esp32: Update machine_bitstream impl to new RMT API.
elvis-epx Nov 24, 2024
165ca03
ports/esp32: Fix bitstream wait until completion.
elvis-epx Dec 2, 2024
f1861c8
ports/esp32: Do not pin RMT to alternate core.
elvis-epx Dec 3, 2024
845373a
ports/esp32: Fix pull-up during channel release.
elvis-epx Dec 6, 2024
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7 changes: 3 additions & 4 deletions docs/esp32/quickref.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -680,8 +680,8 @@ The RMT is ESP32-specific and allows generation of accurate digital pulses with
import esp32
from machine import Pin

r = esp32.RMT(0, pin=Pin(18), clock_div=8)
r # RMT(channel=0, pin=18, source_freq=80000000, clock_div=8)
r = esp32.RMT(pin=Pin(18), clock_div=8)
r # RMT(pin=18, source_freq=80000000, clock_div=8)
# The channel resolution is 100ns (1/(source_freq/clock_div)).
r.write_pulses((1, 20, 2, 40), 0) # Send 0 for 100ns, 1 for 2000ns, 0 for 200ns, 1 for 4000ns

Expand Down Expand Up @@ -743,8 +743,7 @@ The APA106 driver extends NeoPixel, but internally uses a different colour order
``NeoPixel`` object.

For low-level driving of a NeoPixel see `machine.bitstream`.
This low-level driver uses an RMT channel by default. To configure this see
`RMT.bitstream_channel`.
This low-level driver uses an RMT channel by default.

APA102 (DotStar) uses a different driver as it has an additional clock pin.

Expand Down
58 changes: 37 additions & 21 deletions docs/library/esp32.rst
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Expand Up @@ -177,11 +177,11 @@ used to transmit or receive many other types of digital signals::
import esp32
from machine import Pin

r = esp32.RMT(0, pin=Pin(18), clock_div=8)
r # RMT(channel=0, pin=18, source_freq=80000000, clock_div=8, idle_level=0)
r = esp32.RMT(pin=Pin(18), clock_div=8)
r # RMT(pin=18, source_freq=80000000, clock_div=8, idle_level=0)

# To apply a carrier frequency to the high output
r = esp32.RMT(0, pin=Pin(18), clock_div=8, tx_carrier=(38000, 50, 1))
r = esp32.RMT(pin=Pin(18), clock_div=8, tx_carrier=(38000, 50, 1))

# The channel resolution is 100ns (1/(source_freq/clock_div)).
r.write_pulses((1, 20, 2, 40), 0) # Send 0 for 100ns, 1 for 2000ns, 0 for 200ns, 1 for 4000ns
Expand Down Expand Up @@ -210,13 +210,17 @@ For more details see Espressif's `ESP-IDF RMT documentation.
*beta feature* and the interface may change in the future.


.. class:: RMT(channel, *, pin=None, clock_div=8, idle_level=False, tx_carrier=None)
.. class:: RMT(channel, *, pin=None, clock_div=8, idle_level=False, num_symbols=64, tx_carrier=None)

This class provides access to one of the eight RMT channels. *channel* is
required and identifies which RMT channel (0-7) will be configured. *pin*,
also required, configures which Pin is bound to the RMT channel. *clock_div*
optional and a dummy parameter for backward compatibility. *pin* is required
and configures which Pin is bound to the RMT channel. *clock_div*
is an 8-bit clock divider that divides the source clock (80MHz) to the RMT
channel allowing the resolution to be specified. *idle_level* specifies
channel allowing the resolution to be specified. *num_symbols* specifies the
RMT buffer allocated for this channel (minimum 64), from a small pool of
512 symbols that are shared by all channels. This buffer does not limit the
size of the pulse train that you can send, but bigger buffers reduce the
CPU load and the potential of glitches/imprecise pulse lengths. *idle_level* specifies
what level the output will be when no transmission is in progress and can
be any value that converts to a boolean, with ``True`` representing high
voltage and ``False`` representing low.
Expand All @@ -241,14 +245,38 @@ For more details see Espressif's `ESP-IDF RMT documentation.
Returns ``True`` if the channel is idle or ``False`` if a sequence of
pulses started with `RMT.write_pulses` is being transmitted. If the
*timeout* keyword argument is given then block for up to this many
milliseconds for transmission to complete.
milliseconds for transmission to complete. Timeout of -1 blocks until
transmission is complete (and blocks forever if loop is enabled).

.. method:: RMT.loop(enable_loop)

Configure looping on the channel. *enable_loop* is bool, set to ``True`` to
enable looping on the *next* call to `RMT.write_pulses`. If called with
``False`` while a looping sequence is currently being transmitted then the
current loop iteration will be completed and then transmission will stop.
transmission will stop. (Method deprecated by `RMT.loop_count`.)

.. method:: RMT.loop_count(n)

Configure looping on the channel. *n* is int. Affects the *next* call to
`RMT.write_pulses`. Set to ``0`` to disable looping, ``-1`` to enable
infinite looping, or a positive number to loop for a given number of times.
If *n* is changed, the current transmission is stopped.

Note: looping for a finite number of times is not supported by all flavors
of ESP32.

.. method:: RMT.disable()

Disable RMT channel. This is useful to stop an infinite transmission loop.
The current loop is finished and transmission stops.
The object is not invalidated, and the RMT channel is again enabled when a new
transmission is started.

.. method:: RMT.release()

Release all RMT resources and invalidate the object. All subsequent method
calls will raise OSError. Useful to free RMT resources without having to wait
for the object to be garbage-collected.

.. method:: RMT.write_pulses(duration, data=True)

Expand Down Expand Up @@ -278,18 +306,6 @@ For more details see Espressif's `ESP-IDF RMT documentation.
new sequence of pulses. Looping sequences longer than 126 pulses is not
supported by the hardware.

.. staticmethod:: RMT.bitstream_channel([value])

Select which RMT channel is used by the `machine.bitstream` implementation.
*value* can be ``None`` or a valid RMT channel number. The default RMT
channel is the highest numbered one.

Passing in ``None`` disables the use of RMT and instead selects a bit-banging
implementation for `machine.bitstream`.

Passing in no argument will not change the channel. This function returns
the current channel number.

Constants
---------

Expand Down
8 changes: 8 additions & 0 deletions ports/esp32/esp32_common.cmake
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Expand Up @@ -237,6 +237,14 @@ target_link_options(${MICROPY_TARGET} PUBLIC
target_include_directories(${MICROPY_TARGET} PUBLIC
${IDF_PATH}/components/bt/host/nimble/nimble
)
if (IDF_VERSION VERSION_LESS "5.3")
# Additional include directories needed for private RMT header.
# IDF 5.x versions before 5.3.1
message(STATUS "Using private rmt headers for ${IDF_VERSION}")
target_include_directories(${MICROPY_TARGET} PRIVATE
${IDF_PATH}/components/driver/rmt
)
endif()

# Add additional extmod and usermod components.
target_link_libraries(${MICROPY_TARGET} micropy_extmod_btree)
Expand Down
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