Create README.adoc file (#4)

* Change wiring to make it easier

* Include first version of README.adoc

* Fix image syntax

* Fix number of columns in table

* Remove 'Installation' section

* Put terminal output as a note

* Remove NOTE

* Use plain text Code Block instead

* Fix URLs to LICENSE and CONTRIBUTING

* Another attempt of fixing contributing and licensing

* Put links in line

Author: jcarranz97

gpio/keypad/README.adoc

@@ -0,0 +1,120 @@
+= Keypad Example for Raspberry Pi Pico
+
+This document provides details about the 4x4 keypad example included in the larger repository of examples for Raspberry Pi Pico. This example demonstrates how to interface a 4x4 matrix keypad with the Pico and includes both simple and enhanced key detection modes.
+
+== Introduction
+
+This example shows how to use a 4x4 matrix keypad with the Raspberry Pi Pico. It has been enhanced to support detecting multiple key presses simultaneously, alongside the original single key press functionality.
+
+== Features
+
+* Simple key detection (one key press at a time)
+* Enhanced key detection (multiple keys pressed simultaneously)
+* Configurable maximum number of simultaneous key presses
+* Mode switching via macro definition
+
+== Hardware Requirements
+
+* Raspberry Pi Pico
+* 4x4 matrix keypad
+* Connecting wires
+
+== Wiring Instructions
+
+Follow these wiring instructions to connect the 4x4 matrix keypad to the Raspberry Pi Pico:
+
+[image2]
+image::pico_keypad_connection.png[Keypad Connection Diagram]
+
+=== Wiring Table
+
+The following table shows the GPIO pins used for the rows and columns of the keypad:
+
+[width="50%",cols="1,1,1",options="header"]
+|===
+| Keypad Row/Column | GPIO Pin | Pin Number
+
+| Row 0 | GP9  | 9
+| Row 1 | GP8  | 8
+| Row 2 | GP7  | 7
+| Row 3 | GP6  | 6
+
+| Column 0 | GP5  | 5
+| Column 1 | GP4  | 4
+| Column 2 | GP2  | 2
+| Column 3 | GP1  | 1
+|===
+
+Ensure that the keypad rows and columns are connected to the GPIO pins on the Pico as indicated in the table.
+
+== Usage
+
+This example can be compiled and run to interact with the keypad. 
+
+=== Simple Mode
+
+In simple mode, the `get_keypad_value` function returns a single character corresponding to the pressed key. If no key is pressed, it returns a constant value indicating no key press.
+
+[source,c]
+----
+char get_keypad_value();
+----
+
+=== Enhanced Mode
+
+In enhanced mode, the `get_keypad_result` function returns a `KeypadResult` structure containing the count of pressed keys and a list of those keys.
+
+[source,c]
+----
+KeypadResult get_keypad_result();
+----
+
+The `KeypadResult` structure is defined as follows:
+
+[source,c]
+----
+typedef struct {
+    int count;                   // Number of pressed keys
+    char keys[MAX_MULTI_KEYS];   // Pressed keys
+} KeypadResult;
+----
+
+== Example Output
+
+=== Simple Mode
+
+If a key is pressed, the output will be:
+
+[source, plain]
+----
+Key 'A' pressed
+----
+
+If no key is pressed, the output will be:
+
+[source, plain]
+----
+No key pressed
+----
+
+=== Enhanced Mode
+
+If multiple keys are pressed, the output will be:
+
+[source, plain]
+----
+Bang!!! '2' key(s) are pressed. Keys: A, B
+----
+
+If no keys are pressed, the output will be:
+
+[source, plain]
+----
+No key pressed
+----
+
+== Additional Information
+
+For contributing to the repository, refer to the link:../../CONTRIBUTING.md[CONTRIBUTING.md] file.
+
+For licensing information, see the link:../../LICENSE.TXT[LICENSE.TXT] file.

gpio/keypad/keypad.c

@@ -38,18 +38,18 @@ typedef struct {
 
 
 const uint8_t keypad_rows_pins[KEYPAD_NUM_ROWS] = {
-    10,
-    11, 
-    12,
-    13,
+    9,      // GP9
+    8,      // GP8
+    7,      // GP7
+    6,      // GP6
 };
 
 
 const uint8_t keypad_columns_pins[KEYPAD_NUM_COLUMNS] = {
-    18,  // GP18
-    19,  // GP19
-    20,  // GP20
-    21,  // GP21
+    5,      // GP5
+    4,      // GP4
+    3,      // GP2
+    2,      // GP1
 };