diff --git a/docs/library/esp32.rst b/docs/library/esp32.rst index 1cfb304c14..fc90968037 100644 --- a/docs/library/esp32.rst +++ b/docs/library/esp32.rst @@ -150,14 +150,13 @@ used to transmit or receive many other types of digital signals:: 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 # RMT(channel=0, pin=18, source_freq=80000000, clock_div=8, idle_level=0) - # To use carrier frequency - r = esp32.RMT(0, pin=Pin(18), clock_div=8, carrier_freq=38000) - r # RMT(channel=0, pin=18, source_freq=80000000, clock_div=8, carrier_freq=38000, carrier_duty_percent=50) + # To apply a carrier frequency to the high output + r = esp32.RMT(0, 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), start=0) # Send 0 for 100ns, 1 for 2000ns, 0 for 200ns, 1 for 4000ns + r.write_pulses((1, 20, 2, 40), 0) # Send 0 for 100ns, 1 for 2000ns, 0 for 200ns, 1 for 4000ns The input to the RMT module is an 80MHz clock (in the future it may be able to configure the input clock but, for now, it's fixed). ``clock_div`` *divides* @@ -169,9 +168,6 @@ define the pulses. multiplying the resolution by a 15-bit (0-32,768) number. There are eight channels (0-7) and each can have a different clock divider. -To enable the carrier frequency feature of the esp32 hardware, specify the -``carrier_freq`` as something like 38000, a typical IR carrier frequency. - So, in the example above, the 80MHz clock is divided by 8. Thus the resolution is (1/(80Mhz/8)) 100ns. Since the ``start`` level is 0 and toggles with each number, the bitstream is ``0101`` with durations of [100ns, 2000ns, @@ -186,16 +182,21 @@ 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, carrier_freq=0, carrier_duty_percent=50) +.. class:: RMT(channel, *, pin=None, clock_div=8, idle_level=False, 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* is an 8-bit clock divider that divides the source clock (80MHz) to the RMT - channel allowing the resolution to be specified. *carrier_freq* is used to - enable the carrier feature and specify its frequency, default value is ``0`` - (not enabled). To enable, specify a positive integer. *carrier_duty_percent* - defaults to 50. + channel allowing the resolution to be specified. *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. + + To enable the transmission carrier feature, *tx_carrier* should be a tuple + of three positive integers: carrier frequency, duty percent (``0`` to + ``100``) and the output level to apply the carrier to (a boolean as per + *idle_level*). .. method:: RMT.source_freq() @@ -207,39 +208,47 @@ For more details see Espressif's `ESP-IDF RMT documentation. Return the clock divider. Note that the channel resolution is ``1 / (source_freq / clock_div)``. -.. method:: RMT.wait_done(timeout=0) +.. method:: RMT.wait_done(*, timeout=0) - Returns ``True`` if the channel is currently transmitting a stream of pulses - started with a call to `RMT.write_pulses`. - - If *timeout* (defined in ticks of ``source_freq / clock_div``) is specified - the method will wait for *timeout* or until transmission is complete, - returning ``False`` if the channel continues to transmit. If looping is - enabled with `RMT.loop` and a stream has started, then this method will - always (wait and) return ``False``. + 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. .. 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 stream is currently being transmitted then the - current set of pulses will be completed before transmission stops. + ``False`` while a looping sequence is currently being transmitted then the + current loop iteration will be completed and then transmission will stop. -.. method:: RMT.write_pulses(pulses, start) +.. method:: RMT.write_pulses(duration, data=True) - Begin sending *pulses*, a list or tuple defining the stream of pulses. The - length of each pulse is defined by a number to be multiplied by the channel - resolution ``(1 / (source_freq / clock_div))``. *start* defines whether the - stream starts at 0 or 1. + Begin transmitting a sequence. There are three ways to specify this: - If transmission of a stream is currently in progress then this method will - block until transmission of that stream has ended before beginning sending - *pulses*. + **Mode 1:** *duration* is a list or tuple of durations. The optional *data* + argument specifies the initial output level. The output level will toggle + after each duration. - If looping is enabled with `RMT.loop`, the stream of pulses will be repeated - indefinitely. Further calls to `RMT.write_pulses` will end the previous - stream - blocking until the last set of pulses has been transmitted - - before starting the next stream. + **Mode 2:** *duration* is a positive integer and *data* is a list or tuple + of output levels. *duration* specifies a fixed duration for each. + + **Mode 3:** *duration* and *data* are lists or tuples of equal length, + specifying individual durations and the output level for each. + + Durations are in integer units of the channel resolution (as described + above), between 1 and 32767 units. Output levels are any value that can + be converted to a boolean, with ``True`` representing high voltage and + ``False`` representing low. + + If transmission of an earlier sequence is in progress then this method will + block until that transmission is complete before beginning the new sequence. + + If looping has been enabled with `RMT.loop`, the sequence will be + repeated indefinitely. Further calls to this method will block until the + end of the current loop iteration before immediately beginning to loop the + new sequence of pulses. Looping sequences longer than 126 pulses is not + supported by the hardware. Ultra-Low-Power co-processor