Add printedpad keyboard (#21202)

Co-authored-by: jack <0x6a73@protonmail.com>
Co-authored-by: Drashna Jaelre <drashna@live.com>

keyboards/printedpad/printedpad.c

@@ -0,0 +1,57 @@
+// Copyright 2023 Noah Beidelman (@noahbei)
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include QMK_KEYBOARD_H
+#include "printedpad.h"
+
+void board_init(void) {
+  SYSCFG->CFGR1 |= SYSCFG_CFGR1_I2C1_DMA_RMP;
+}
+
+const uint8_t max_layer = 3;
+uint8_t current_display_mode = 0;
+
+bool key_pressed = false;
+
+bool process_record_kb(uint16_t keycode, keyrecord_t *record) {
+    if (!process_record_user(keycode, record)) {
+        return false;
+    }
+#ifdef OLED_ENABLE
+    key_pressed = record->event.pressed;
+#endif
+    switch(keycode) {
+        case LT(0, KC_NO):
+            if (record->event.pressed) {
+                // on tap
+                if (record->tap.count) {
+                    if (get_highest_layer(layer_state) >= max_layer) {
+                        layer_clear(); 
+                    } else { 
+                        layer_move(get_highest_layer(layer_state) + 1);
+                    }
+                }
+#ifdef OLED_ENABLE
+                // on hold
+                else {
+                    current_display_mode = (current_display_mode + 1) % 3;
+                }
+#endif
+            }
+            return false;
+    }
+    return true;
+}
+
+#ifdef OLED_ENABLE
+uint32_t flash_timer = 0;
+bool layer_changed = false;
+
+// when the layer is changed, flash the layer number on the screen
+layer_state_t layer_state_set_kb(layer_state_t state) {
+    flash_timer = timer_read();
+    layer_changed = true;
+    
+    return layer_state_set_user(state);
+}
+#endif