esp32/encoder: Add Encoder and Counter classes.

Signed-off-by: IhorNehrutsa <[email protected]>

Author: IhorNehrutsa

docs/esp32/general.rst

@@ -50,8 +50,12 @@ For your convenience, some of technical specifications are provided below:
 * SPI: 4 SPI interfaces (one used for FlashROM)
 * I2C: 2 I2C (bitbang implementation available on any pins)
 * I2S: 2
+* CAN bus: 1
 * ADC: 12-bit SAR ADC up to 18 channels
 * DAC: 2 8-bit DACs
+* PCNT: up to 8 channels
+* PWM: up to 16 channels
+* MCPWM: up to 2 channels
 * RMT: 8 channels allowing accurate pulse transmit/receive
 * Programming: using BootROM bootloader from UART - due to external FlashROM
   and always-available BootROM bootloader, the ESP32 is not brickable

docs/esp32/img/quad.png

@@ -0,0 +1,256 @@
+PCNT - Counter and Encoder
+==========================
+
+The Counter and Encoder use the ESP32 Pulse Counter (PCNT) hardware peripheral,
+see Espressif's `ESP-IDF Pulse Counter documentation.
+<https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/peripherals/pcnt.html>`_
+
+For the counter not to miss any pulses, the pulse duration should be longer than one ESP32 APB_CLK cycle (1 / 80 MHz = 12.5 ns).
+The pulses are sampled on the edges of the APB_CLK clock and may be missed if fall between the edges.
+With ideal input signal maximum frequency of measured pulses is APB_CLK / 2 = 80 MHz / 2 = 40 MHz.
+
+The inputs have optional filters that can be used to discard unwanted glitches in the signal.
+The length of ignored pulses is provided in APB_CLK clock cycles.
+* Note: Filter value is a 10-bit value, so the maximum filter value should be limited to 1023.
+Maximum filtered glitches delay is 1023 * 12.5 ns = 12.7875 us.
+Big filter make cutbacks the input frequency: 1 / (12.7875 us * 2) = 39.1 kHz.
+* Note: Do not neglect circuitry methods to reduce noise (right powering and grounding, filtering, shielding,
+short conductors, twisted pair cable, differential signals, etc.).
+
+There is only one interrupt for the peripheral, and that is managed inside the module.
+The user has no interrupt interface, and no interrupts are generated on each pulse.
+Interrupts arrive when the 16-bit hardware counter buffer overflows, so this module has a tiny interrupt footprint
+while providing support for up to 8 simultaneous counters (Encoder or Counter objects).
+
+.. _esp32_machine.Counter:
+
+Counter
+=======
+
+The Pulse Counter service.
+
+Constructor
+-----------
+
+.. class:: Counter(id, src=None, \*, direction=Counter.UP, _src=None, edge=Counter.RISING, filter_ns=0)
+
+    The Counter starts to count immediately. Filtering is disabled.
+
+      - *id*. Values of *id* depend on a particular port and its hardware.
+        Values 0, 1, etc. are commonly used to select hardware block #0, #1, etc.
+
+      - *src* is the pulse input :ref:`machine.Pin <machine.Pin>` to be monitored.
+        *src* is required in the constructor.
+
+      - *direction* specifies the direction to count. Values for this include the constants
+
+        - Counter.UP - (default value) and
+        - Counter.DOWN to control the direction by software or
+        - :ref:`machine.Pin <machine.Pin>` object to control the direction externally. If ``Pin.value()``:
+           - 0 - count down,
+           - 1 - count up.
+
+      - *_src* is the inverse pulse input :ref:`machine.Pin <machine.Pin>` to be monitored.
+        If the *_src* keyword is present then the *direction* keyword does not matter.
+        *src* and *_src* count in opposite directions, one in the UP direction
+        and the other in the DOWN direction, i.e. as an incremental/decremental counter.
+
+      - *edge* specifies which edges of the input signal will be counted by Counter:
+
+        - Counter.RISING : raise edges,
+        - Counter.FALLING : fall edges,
+        - Counter.RISING | Counter.FALLING : both edges.
+
+      - *filter_ns* specifies a ns-value for the minimal time a signal has to be stable
+        at the input to be recognized. The largest value is 12787ns (1023 * 1000000000 / APB_CLK_FREQ).
+        The default is 0 – no filter.
+
+Methods
+-------
+
+.. method:: Counter.init(*, src, ...)
+
+   Modify the settings of the Counter object. See the **Constructor** for details about the parameters.
+
+.. method:: Counter.deinit()
+
+   Stops the Counter, disables interrupts and releases hardware resources used by the counter.
+   A Soft Reset involve deinitializing all Encoder objects.
+
+.. method:: Counter.filter([value])
+
+   Get, and optionally set, the filter value. 0 disable filtering.
+
+.. method:: Counter.value([value])
+
+   Get, and optionally set, the counter *value* as a signed 64-bit integer.
+
+.. method:: Counter.irq(handler=None, trigger=Counter.IRQ_MATCH1 | Counter.IRQ_ZERO, value=0)
+
+   -*handler* specifies a function is called when the respective *trigger* event happens.
+    The callback function *handler* receives a single argument, which is the Counter object.
+    All events may share the same callback or have separate callbacks.
+    The callback will be disabled, when called with handler=None. Counter.irq() disable all callbacks.
+    The event which triggers the callback can be identified with the ``Counter.status()`` method.
+    The Counter object which triggers the callback can be identified with the ``Counter.id()`` method.
+
+   -*trigger* events may be:
+
+    - Counter.IRQ_MATCH1 triggered when the counter matches the match1 value.
+    - Counter.IRQ_ZERO triggered when the counter matches the 0.
+
+    The default is - trigger=Counter.IRQ_MATCH1 | Counter.IRQ_ZERO.
+    The events are triggered when the counter value and match value are identical, but
+    callbacks have always a latency.
+
+   - *value* sets a counter match1 value. When the counter matches these values,
+     a callback function can be called. They are 0 by default.
+
+Attention: ``Counter.irq()`` resets counter to 0.
+
+.. method:: Counter.status()
+
+   Returns the event status flags of the recent handled Counter interrupt as a bitmap.
+
+.. method:: Counter.id()
+
+   Returns id number.
+
+.. method:: Counter.pause()
+
+.. method:: Counter.resume()
+
+Constants
+---------
+
+.. data:: Counter.UP
+          Counter.DOWN
+
+   Selects the counter direction.
+
+.. data:: Counter.RISING
+          Counter.FALLING
+
+   Selects the counted edges.
+
+.. data:: Counter.IRQ_MATCH1
+          Counter.IRQ_ZERO
+
+   Selects callback triggers.
+
+::
+
+    from machine import Counter, Pin
+
+    try:
+        def irq_handler(self):
+            print('irq_handler()', self.id(), self.status(), self.value())
+
+        cnt = Counter(0, src=Pin(17, mode=Pin.IN), direction=Pin(16, mode=Pin.IN))
+
+        cnt.pause()
+        flt = cnt.filter()  # return current filter value.
+        cnt.filter(10_000)  # filter delay is 10ms
+        c = cnt.value(0)  # get current counter value, set the counter value to 0
+        cnt.irq(irq_handler, Counter.IRQ_ZERO)  # set irq handler
+        cnt.resume()
+
+        _c = None
+        while True:
+            c = cnt.value()  # get the counter value
+            if _c != c:
+                _c = c
+                print('Counter =', c)
+    finally:
+        cnt.deinit()  # free the input pins and counter.
+
+
+.. _esp32_machine.Encoder:
+
+Encoder
+=======
+
+This class provides a Quadrature Incremental Encoder service.
+See `Quadrature encoder outputs.
+<https://en.wikipedia.org/wiki/Incremental_encoder#Quadrature_outputs>`_
+
+.. image:: img/quad.png
+    :width: 397px
+
+Constructor
+-----------
+
+.. class:: Encoder(id, phase_a=None, phase_b=None, \*, x124=4, filter_ns=0, match1=0)
+
+    The Encoder starts to count immediately. Filtering is disabled.
+
+      - *id*. Values of *id* depend on a particular port and its hardware.
+        Values 0, 1, etc. are commonly used to select hardware block #0, #1, etc.
+
+      - *phase_a*, *phase_b* are input pins :ref:`machine.Pin <machine.Pin>` for monitoring of quadrature encoder pulses.
+        They are required in the constructor.
+
+      - *x124* is a hardware multiplier, possible values is 1, 2, 4. The default value is 4.
+        More info in `Quadrature decoder state table <https://en.wikipedia.org/wiki/Incremental_encoder#Quadrature_decoder>`_.
+        When more Encoder resolution is needed, it is possible for the encoder to count the leading
+        and trailing edges of the quadrature encoder’s pulse train from one channel,
+        which doubles (x2) the number of pulses. Counting both leading and trailing edges
+        of both channels (A and B channels) of a quadrature encoder will quadruple (x4) the number of pulses:
+
+          - 1 - count the leading(or trailing) edges from one phase channel.
+          - 2 - count the leading and trailing edges from one phase channel.
+          - 4 - count both leading and trailing edges of both phase channels.
+
+    These keywords are the same as the Counter keywords, see above:
+      - *filter_ns*
+      - *match1*
+
+Methods
+-------
+
+.. method:: Encoder.init(*, phase_a, ...)
+
+   Modify the settings of the Encoder object. See the **Constructor** for details about the parameters.
+
+The Encoder has the same methods as the Counter and differs only
+in the constructor and internal hardware PCNT initialization.
+
+Constants
+---------
+
+.. data:: Encoder.IRQ_MATCH1
+          Encoder.IRQ_ZERO
+
+   Selects callback triggers.
+
+::
+
+    from machine import Encoder, Pin
+
+    try:
+        n = 0
+        def irq_handler1(self):
+            n -= 1
+            print('irq_handler1()', self.id(), self.value(), n)
+
+        def irq_handler2(self):
+            n += 1
+            print('irq_handler2()', self.id(), self.value(), n)
+
+        enc = Encoder(0, phase_a=Pin(17, mode=Pin.IN), phase_b=Pin(16, mode=Pin.IN), match1=1000)
+
+        enc.pause()
+        flt = enc.filter()  # return current filter value.
+        enc.filter(10_000)  # filter delay is 10ms
+        c = enc.value(0)  # get current encoder value, set the encoder value to 0
+        enc.irq(irq_handler1, Encoder.IRQ_MATCH1)  # set irq handler
+        enc.resume()
+
+        _c = None
+        while True:
+            c = enc.value()  # get the encoder value
+            if _c != c:
+                _c = c
+                print('Encoder =', c)
+    finally:
+        enc.deinit()  # free the input pins and encoder.

docs/esp32/pcnt.rst

@@ -16,6 +16,7 @@ working with this board it may be useful to get an overview of the microcontroll
    :maxdepth: 1
 
    general.rst
+   pcnt.rst
    tutorial/index.rst
 
 Installing MicroPython
@@ -674,6 +675,45 @@ The RMT is ESP32-specific and allows generation of accurate digital pulses with
     # 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
 
+Counter (Pulse/Edge Counter)
+----------------------------
+
+The Counter counts the number of rising and/or falling edges on any input pin.
+It is a 64-bit signed hardware-based counter. Counter and Encoder share the same ESP32 PCNT hardware peripheral,
+the total summary available number of Counter and Encoder is up to 8.
+
+See :ref:`machine.Counter <esp32_machine.Counter>` for details.  Simplest usage is::
+
+    from machine import Pin, Counter
+
+    cnt = Counter(0, src=Pin(17, mode=Pin.IN), direction=Pin(16, mode=Pin.IN))
+    _v = None
+    while True:
+        v = cnt.value()  # get 64-bit signed value
+        if _v != v:
+            _v = v
+            print('Counter value:', v)
+
+Encoder (Quadrature Incremental Encoder)
+----------------------------------------
+
+The Encoder counts the quadrature-encoded pulses on pair of input pins (two square wave signals A and B with
+~50% duty cycle and ~90-degree phase difference between them).
+It is a 64-bit signed hardware-based counter. Counter and Encoder share the same ESP32 PCNT hardware peripheral,
+the total summary available number of Counter and Encoder is up to 8.
+
+See :ref:`machine.Encoder <esp32_machine.Encoder>` for details.  Simplest usage is::
+
+    from machine import Pin, Encoder
+
+    enc = Encoder(0, phase_a=Pin(17, mode=Pin.IN), phase_b=Pin(16, mode=Pin.IN))
+    _v = None
+    while True:
+        v = enc.value()  # get 64-bit signed value
+        if _v != v:
+            _v = v
+            print('Encoder value:', v)
+
 OneWire driver
 --------------
 

docs/esp32/quickref.rst

@@ -16,7 +16,6 @@ to `<https://www.python.org>`__.
 
 .. toctree::
    :maxdepth: 1
-   :numbered:
 
    intro.rst
    pwm.rst

docs/esp32/tutorial/index.rst

@@ -5,6 +5,7 @@
 
 #define MICROPY_HW_ENABLE_SDCARD            (0)
 #define MICROPY_PY_MACHINE_I2S              (0)
+#define MICROPY_PY_MACHINE_PCNT             (0)
 
 // Enable UART REPL for modules that have an external USB-UART and don't use native USB.
 #define MICROPY_HW_ENABLE_UART_REPL         (1)

lib/micropython-lib

@@ -69,6 +69,7 @@ list(APPEND MICROPY_SOURCE_PORT
     machine_touchpad.c
     machine_dac.c
     machine_i2c.c
+    machine_encoder.c
     network_common.c
     network_lan.c
     network_ppp.c