diff --git a/cores/arduino/Serial.cpp b/cores/arduino/Serial.cpp
index d905edd90..7d7a0ad87 100644
--- a/cores/arduino/Serial.cpp
+++ b/cores/arduino/Serial.cpp
@@ -61,9 +61,13 @@ void UART::WrapperCallback(uart_callback_args_t *p_args) {
       case UART_EVENT_TX_COMPLETE:
       case UART_EVENT_TX_DATA_EMPTY:
       {
-        //uint8_t to_enqueue = uart_ptr->txBuffer.available() < uart_ptr->uart_ctrl.fifo_depth ? uart_ptr->txBuffer.available() : uart_ptr->uart_ctrl.fifo_depth;
-        //while (to_enqueue) {
-        uart_ptr->tx_done = true;
+		  if(uart_ptr->txBuffer.available()){
+			  static char txc;
+			  txc = uart_ptr->txBuffer.read_char();
+			  R_SCI_UART_Write(&(uart_ptr->uart_ctrl), (uint8_t*)&txc , 1);
+		  } else {
+			  uart_ptr->tx_done = true;
+		  }
         break;
       }
       case UART_EVENT_RX_CHAR:
@@ -108,27 +112,31 @@ bool UART::setUpUartIrqs(uart_cfg_t &cfg) {
 /* -------------------------------------------------------------------------- */
 size_t UART::write(uint8_t c) {
 /* -------------------------------------------------------------------------- */  
-  if(init_ok) {
-    tx_done = false;
-    R_SCI_UART_Write(&uart_ctrl, &c, 1);
-    while (!tx_done) {}
-    return 1;
-  }
-  else {
-    return 0;
-  }
+	if(init_ok) {
+		while(txBuffer.isFull()){;}
+		txBuffer.store_char(c);
+		if(tx_done){
+			tx_done = false;
+			txc = txBuffer.read_char();  // clear out the char we just added and send it to start transmission. 
+			R_SCI_UART_Write(&uart_ctrl, (uint8_t*)&txc , 1);		
+		} 
+		return 1;
+	}
+	else {
+		return 0;
+	}
 }
 
 size_t  UART::write(uint8_t* c, size_t len) {
-  if(init_ok) {
-    tx_done = false;
-    R_SCI_UART_Write(&uart_ctrl, c, len);
-    while (!tx_done) {}
-    return len;
-  }
-  else {
-    return 0;
-  }
+	if(init_ok) {
+		for(int i = 0; i<len; i++){
+		  write(c[i]);
+		}
+		return len;
+    }
+    else {
+    	return 0;
+    }
 }
 
 /* -------------------------------------------------------------------------- */
@@ -328,11 +336,5 @@ void UART::flush() {
 /* -------------------------------------------------------------------------- */
 size_t UART::write_raw(uint8_t* c, size_t len) {
 /* -------------------------------------------------------------------------- */
-  size_t i = 0;
-  while (i < len) {
-    uart_ctrl.p_reg->TDR = *(c+i);
-    while (uart_ctrl.p_reg->SSR_b.TEND == 0) {}
-    i++;
-  }
-  return len;
+  return write(c, len);
 }
\ No newline at end of file
diff --git a/cores/arduino/Serial.h b/cores/arduino/Serial.h
index cc818d466..e53a55c71 100644
--- a/cores/arduino/Serial.h
+++ b/cores/arduino/Serial.h
@@ -78,7 +78,8 @@ class UART : public arduino::HardwareSerial {
     arduino::SafeRingBufferN<SERIAL_BUFFER_SIZE> rxBuffer;
     arduino::SafeRingBufferN<SERIAL_BUFFER_SIZE> txBuffer;
 
-    volatile bool tx_done;
+    volatile bool tx_done = true;
+    char txc;
 
     sci_uart_instance_ctrl_t  uart_ctrl;
     uart_cfg_t                uart_cfg;
diff --git a/extras/fsp b/extras/fsp
index 5d13f916c..8ec537bc8 160000
--- a/extras/fsp
+++ b/extras/fsp
@@ -1 +1 @@
-Subproject commit 5d13f916c72f9d1471864361dfaf8f492cab5979
+Subproject commit 8ec537bc86b1b71203d72d0cbb28e6e75b353ebd
diff --git a/extras/uno-r4-wifi-usb-bridge b/extras/uno-r4-wifi-usb-bridge
index a634856e5..3f4e668d1 160000
--- a/extras/uno-r4-wifi-usb-bridge
+++ b/extras/uno-r4-wifi-usb-bridge
@@ -1 +1 @@
-Subproject commit a634856e5467022bc7587e7c8a856811255ea890
+Subproject commit 3f4e668d1318feeaa7088c788e7fd88a26a5a671