From 69e6e69c77bad984d2130b378741417d66c7662c Mon Sep 17 00:00:00 2001
From: Jean Jacques Avril <jean@jeanavril.com>
Date: Wed, 29 Sep 2021 22:31:05 +0200
Subject: [PATCH] scanAsync improved

---
 src/Keyboard.cpp | 42 +++++++-----------------------------------
 1 file changed, 7 insertions(+), 35 deletions(-)

diff --git a/src/Keyboard.cpp b/src/Keyboard.cpp
index f8bc932..3b05df6 100644
--- a/src/Keyboard.cpp
+++ b/src/Keyboard.cpp
@@ -67,41 +67,13 @@ void Keyboard::scanAsync()
     /** Without delay - scanning only one column per cycle **/
     if (millis() < _timeElapsed + this->_debounce)
         return;
-    uint8_t key = 0;
-    switch (_current_scan_col)
-    {
-        default:
-            pcf8574->digitalWrite(7, LOW);
-            _current_scan_col = 1;
-            break;
-        case 1:
-        {
-            scanColumn(&key, 1, 4);
-            pcf8574->digitalWrite(6, LOW);            
-            pcf8574->digitalWrite(7, HIGH);
-            _current_scan_col = 2;
-            break;
-        }
-        case 2:
-        {
-            key=4;
-            scanColumn(&key, 1, 4);
-            pcf8574->digitalWrite(5, LOW);            
-            pcf8574->digitalWrite(6, HIGH);
-            _current_scan_col = 3;
-            break;
-        }
-        case 3:
-        {
-            key=8;
-            scanColumn(&key, 1, 4);
-            pcf8574->digitalWrite(7, LOW);            
-            pcf8574->digitalWrite(5, HIGH);
-            _current_scan_col = 1;
-            break;
-        }
-        break;
-    }
+    uint8_t key = 4*_current_scan_col;
+    scanColumn(&key, 1, 4);
+    pcf8574->digitalWrite(7-(_current_scan_col+1)%3, LOW);
+    pcf8574->digitalWrite(7-_current_scan_col, HIGH);
+    _current_scan_col++; 
+    if(_current_scan_col>2)
+        _current_scan_col = 0;  
 }
 
 void Keyboard::scanColumn(uint8_t* key_ptr, uint8_t start, uint8_t stop){