Commit inicial

3 files changed, 138 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..a71aa19
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+compile_commands.json
+./examples/build/*
+*~
diff --git a/src/keypad.cpp b/src/keypad.cpp
new file mode 100644
index 0000000..2bab18e
--- /dev/null
+++ b/src/keypad.cpp
@@ -0,0 +1,107 @@
+#include "hardware/gpio.h"
+#include "keypad.hpp"
+
+Keypad::Keypad(uint *rows, uint *cols, char chars[4][4]) :
+  rows{rows}, cols{cols}
+{
+  initCharArray(chars);
+  init();
+}
+
+/*
+ * Get pressed key.
+ */
+char Keypad::getKey() {
+  int column_index = pressedColumn();
+  int row_index;
+
+  if(column_index < 0)
+    return '\0';
+
+  pullPinsDown(cols);
+  for(int i = 0; i < KEYPAD_LEN; ++i) {
+    gpio_put(rows[i], 1);
+    int row_state = gpio_get(rows[i]);
+    int column_state = gpio_get(cols[column_index]);
+
+    if(row_state & column_state) {
+      row_index = i;
+
+      break;
+    }
+  }
+  restartPins();
+  
+  return chars[row_index][column_index];
+}
+
+/*
+ * See if a key is pressed.
+ * All columns are pulled up, so if a key is pressed,
+ * its corresponding column should be pulled down.
+ */
+bool Keypad::keyPressed() {
+  return pressedColumn() < 0;
+}
+
+/*
+ * Copy the char matrix passed to the constructor to
+ * the object's chars attribute.
+ */
+void Keypad::initCharArray(char chars[4][4]) {
+  for(int i = 0; i < KEYPAD_LEN; ++i) {
+    for(int j = 0; j < KEYPAD_LEN; ++j)
+      this->chars[i][j] = chars[i][j];
+  }
+}
+
+/*
+ * Initialize the GPIO pins that will be used by the
+ * keypad.
+ * row pins: pulled low and set as outputs.
+ * column pins: pulled high and set as inputs.
+ */
+void Keypad::init() {
+  for (int i = 0; i < KEYPAD_LEN; ++i) {
+    gpio_init(rows[i]);
+    gpio_init(cols[i]);
+    gpio_set_dir(rows[i], OUT);
+    gpio_set_dir(cols[i], IN);
+    gpio_pull_down(rows[i]);
+    gpio_pull_up(cols[i]);
+  }
+}
+
+/*
+ * Get the column that's being pressed.
+ * If no column is getting pressed (i.e, no button
+ * is getting pressed) return -1, otherwise return
+ * the index of the column being pressed.
+ */
+uint Keypad::pressedColumn() {
+  for (int i = 0; i < KEYPAD_LEN; ++i) {
+    if(!gpio_get(cols[i]))
+      return i;
+  }
+
+  return -1;
+}
+
+/*
+ * Pull every GPIO pin in pins down.
+ */
+void Keypad::pullPinsDown(uint *pins) {
+  for(int i = 0; i < KEYPAD_LEN; ++i)
+    gpio_pull_down(pins[i]);
+}
+
+/*
+ * Leave the state of pins as it was before reading.
+ * (Columns pulled up, rows pulled down);
+ */
+void Keypad::restartPins() {
+  for(int i = 0; i < KEYPAD_LEN; ++i) {
+    gpio_pull_up(cols[i]);
+    gpio_put(rows[i], 0);
+  }
+}
diff --git a/src/keypad.hpp b/src/keypad.hpp
new file mode 100644
index 0000000..8a99290
--- /dev/null
+++ b/src/keypad.hpp
@@ -0,0 +1,28 @@
+#include "pico/stdlib.h"
+#define OUT true
+#define IN false
+#define KEYPAD_LEN 4
+#pragma once
+
+class Keypad {
+private:
+  // Start private attributes.
+  uint *rows{};
+  uint *cols{};
+  char chars[4][4];
+  // End private attributes.
+  
+  // Start private methods.
+  void initCharArray(char chars[4][4]);
+  void init();
+  uint pressedColumn();
+  void pullPinsDown(uint *pins);
+  void restartPins();
+  // End private methods.
+public:
+  // Start public methods.
+  Keypad(uint *rows, uint *cols, char chars[4][4]);
+  bool keyPressed();
+  char getKey();
+  // End public methods.
+};