docs/psoc6/quickref.rst: Added I2C slave section.

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

docs/psoc6/quickref.rst

@@ -213,19 +213,22 @@ initialized and configured to work in master mode. The maximum supported frequen
 ::
     
     from machine import I2C
-    i2c = I2C(0, scl='P6_0', sda='P6_1',freq=400000)
+    i2c = I2C(scl='P6_0', sda='P6_1', freq=400000)
 
-Here, ``id=0`` should be passed mandatorily which selects the ``master`` mode operation. The ``scl`` and ``sda`` pins are also required.
+The ``scl`` and ``sda`` pins are the only mandatory arguments. The frequency is optional, and if not passed will be set to 400KHz by default.
+
+.. note::
+    The ``timeout`` option is currently not implemented in this port.
 
 ::
 
     from machine import I2C
-    i2c = I2C(0, scl='P6_0', sda='P6_1')  #I2C is initialized & configured with default frequency
+    i2c = I2C(scl='P6_0', sda='P6_1')  #I2C is initialized & configured with default frequency
 
 ::
 
     from machine import I2C
-    i2c = I2C(0, scl='P9_0', sda='P9_1', freq=400000)  #I2C is initialised & configured with given scl,sda pins & frequency
+    i2c = I2C(scl='P9_0', sda='P9_1', freq=400000)  #I2C is initialised & configured with given scl, sda pins & frequency
 
 Methods
 ^^^^^^^
@@ -235,6 +238,89 @@ All the methods(functions) given in :ref:`machine.I2C <machine.I2C>` class have
 
 All the initialization & configurations are handled by the constructor. Hence ``init()`` is not required.
 
+Hardware I2C bus slave
+----------------------
+
+The PSoC6™ port offers functions to implement an I2C slave device. An I2C master node connected to the slave can exchange data over I2C for the configured slave address and frequency.
+
+.. warning:: 
+    This is not part of the core MicroPython libraries. Therefore, not mapping any existing machine class API and neither supported by other ports.
+
+.. note:: 
+    | Part of the functionality of the I2C slave is based on hardware interrupts and callbacks. 
+    | As explained in this :ref:`section <isr_rules>`, writing interrupts handlers in MicroPython is subject to multiple considerations depending on the actual hardware capabilities and limitations, the specific port implementation, and the overall application design and implementation.
+    | These must kept in mind when implementing accurate timing and event synchronization between master and slave. 
+
+The constructor
+^^^^^^^^^^^^^^^
+
+.. class:: I2CSlave(scl, sda, addr, freq)
+
+    Constructs and returns a new I2C slave object using the following parameters.
+
+    Required arguments: 
+      - *scl* should be a pin name supporting the SCL functionality.
+      - *sda* should be a pin name supporting the SDA functionality.
+      - *addr* should be an 8 bits unsigned integer. 
+
+    Optional arguments:
+      - *freq* should be an integer which sets the maximum frequency
+        for SCL. If not passed, by default is set 400KHz.
+
+    Example:
+        ::
+
+            i2c_slave = I2CSlave(scl="P6_4", sda="P6_5", addr=0x45)
+
+Methods
+^^^^^^^
+
+.. method:: I2CSlave.deinit()
+
+    Deinitialises the I2C slave.
+
+.. method:: I2CSlave.conf_receive_buffer(buf)
+
+    Configures the reception *buf* on an I2C slave. This is the buffer to which the master writes data to. 
+    The user needs to setup a new buffer every time the buffer has been used up.
+
+.. method:: I2CSlave.conf_transmit_buffer(buf)
+
+    Configures the transmission *buf* on an I2C slave. This is the buffer from which the master reads data from.
+    The user needs to setup a new buffer every time the buffer has been used up.
+
+.. method:: I2CSlave.irq(callback, events, priority)
+
+    Enables interrupts and the function handlers to be called upon different I2C bus events.
+
+    Required arguments: 
+      - *callback* should be a function handler that will be executed upon an interrupt event. The callback takes one argument which is the event causing the interrupt.
+      - *events* is the I2C bus events that will be triggering the interrupt. Multiple ones can be configured by ORing the following constants:
+
+        .. data:: I2CSlave.RD_EVENT
+                I2CSlave.WR_EVENT
+                I2CSlave.RD_BUF_IN_FIFO_EVENT
+                I2CSlave.RD_BUF_EMPTY_EVENT
+                I2CSlave.RD_CMPLT_EVENT
+                I2CSlave.WR_CMPLT_EVENT
+                I2CSlave.ERR_EVENT
+
+    Optional arguments:
+      - *priority* should be an unsigned integer with the priority of the interrupt.
+
+    Example:
+        ::
+
+            def cback(event):
+                if event == (event & I2CSlave.WR_EVENT):
+                    print("i2c wr event")
+
+            i2c_slave.irq(callback=cback, events=(I2CSlave.WR_EVENT | I2CSlave.WR_CMPLT_EVENT), priority=1)
+
+.. method:: I2CSlave.irq_disable()
+
+    Disables the I2C slave interrupts.
+
 
 Real time clock (RTC)
 ---------------------