diff --git a/shared/key_matrix.c b/shared/key_matrix.c
index 75c0b67..20d6dfd 100644
--- a/shared/key_matrix.c
+++ b/shared/key_matrix.c
@@ -1,6 +1,45 @@
 #include "fsl_gpio.h"
 #include "key_matrix.h"
 
+#ifdef OLD_MATRIX
+
+// This ifdef clause will be completely erased as soon as Santiago's prototype will be out of use.
+// Since the creation of his v6.0 prototype the diodes of the key matrix have been reversed in order
+// to optimize the key scanning algorithm.
+
+void KeyMatrix_Init(key_matrix_t *keyMatrix)
+{
+    for (uint8_t col_i=0; col_i<keyMatrix->colNum; col_i++) {
+        key_matrix_pin_t col = keyMatrix->cols[col_i];
+        CLOCK_EnableClock(col.clock);
+        PORT_SetPinConfig(col.port, col.pin,
+                          &(port_pin_config_t){.pullSelect=kPORT_PullDisable, .mux=kPORT_MuxAsGpio});
+        GPIO_PinInit(col.gpio, col.pin, &(gpio_pin_config_t){kGPIO_DigitalOutput, 0});
+    }
+
+    for (uint8_t row_i=0; row_i<keyMatrix->rowNum; row_i++) {
+        key_matrix_pin_t row = keyMatrix->rows[row_i];
+        CLOCK_EnableClock(row.clock);
+        PORT_SetPinConfig(row.port, row.pin,
+                          &(port_pin_config_t){.pullSelect=kPORT_PullDown, .mux=kPORT_MuxAsGpio});
+        GPIO_PinInit(row.gpio, row.pin, &(gpio_pin_config_t){kGPIO_DigitalInput});
+    }
+}
+
+void KeyMatrix_Scan(key_matrix_t *keyMatrix)
+{
+    for (uint8_t col=0; col<keyMatrix->colNum; col++) {
+        GPIO_WritePinOutput(keyMatrix->cols[col].gpio, keyMatrix->cols[col].pin, 1);
+        for (uint8_t row=0; row<keyMatrix->rowNum; row++) {
+            keyMatrix->keyStates[row*keyMatrix->colNum + col] = GPIO_ReadPinInput(keyMatrix->rows[row].gpio, keyMatrix->rows[row].pin);
+        }
+        GPIO_WritePinOutput(keyMatrix->cols[col].gpio, keyMatrix->cols[col].pin, 0);
+        for (volatile uint32_t i=0; i<100; i++); // Wait for the new port state to settle. This avoid bogus key state detection.
+    }
+}
+
+#else
+
 void KeyMatrix_Init(key_matrix_t *keyMatrix)
 {
     for (key_matrix_pin_t *row = keyMatrix->rows; row < keyMatrix->rows + keyMatrix->rowNum; row++) {
@@ -37,3 +76,5 @@ void KeyMatrix_Scan(key_matrix_t *keyMatrix)
         for (volatile uint32_t i=0; i<100; i++); // Wait for the new port state to settle. This avoid bogus key state detection.
     }
 }
+
+#endif