Wire: unlock the bus on begin()

Author: facchinm

Diff for: libraries/Wire/Wire.cpp

@@ -405,6 +405,19 @@ void TwoWire::_begin(void) {
          init_ok = false;
       }
   }
+
+  if (init_ok) {
+    // inspired by https://community.element14.com/products/roadtest/b/blog/posts/using-i2c-spi-and-dma-on-renesas-ra2l1-part-1
+    // abort previous transactions
+    if (!is_sci) {
+      for (int i = 0; i < 20; i++) {
+        m_i2c_ctrl.p_reg->ICCR1_b.CLO = 1;
+        while (m_i2c_ctrl.p_reg->ICCR1_b.CLO) {
+        }
+      }
+    }
+    m_abort(&m_i2c_ctrl);
+  }
 }
 
 /* -------------------------------------------------------------------------- */