add warnings to keypad and rp2pio as well

Author: dhalbert

ports/raspberrypi/bindings/rp2pio/__init__.c

@@ -17,6 +17,11 @@
 //|     introduction and guide to working with PIO in CircuitPython, see `this
 //|     Learn guide <https://learn.adafruit.com/intro-to-rp2040-pio-with-circuitpython>`_.
 //|
+//| .. warning:: Using PIO inputs on Raspberry Pi RP2350 A2 stepping has some limitations
+//|    due to a GPIO hardware issue that causes excessive leakage current (~120uA).
+//|    A pin can read as high even when driven or pulled low, if the input signal is high
+//|    impedance or if an attached pull-down resistor is too weak (has too high a value).
+//|    See the warning in `digitalio` for more information.
 //| """
 //|
 

shared-bindings/keypad/__init__.c

@@ -70,6 +70,12 @@ const mp_obj_property_t keypad_generic_events_obj = {
 //| For more information about working with the `keypad` module in CircuitPython,
 //| see `this Learn guide <https://learn.adafruit.com/key-pad-matrix-scanning-in-circuitpython>`_.
 //|
+//| .. warning:: Using pull-downs with `keypad` on Raspberry Pi RP2350 A2 stepping has some limitations
+//|    due to a GPIO hardware issue that causes excessive leakage current (~120uA).
+//|    A pin can read as high even when driven or pulled low, if the input signal is high
+//|    impedance or if an attached pull-down resistor is too weak (has too high a value).
+//|    See the warning in `digitalio` for more information.
+//|
 //| .. jinja
 //| """