diff --git a/os/hal/include/uart.h b/os/hal/include/uart.h
index c0ee4c9ef..444975d15 100644
--- a/os/hal/include/uart.h
+++ b/os/hal/include/uart.h
@@ -106,9 +106,12 @@ extern "C" {
   void uartStop(UARTDriver *uartp);
   void uartStartSend(UARTDriver *uartp, size_t n, const void *txbuf);
   void uartStartSendI(UARTDriver *uartp, size_t n, const void *txbuf);
-  void uartStopSend(UARTDriver *uartp);
+  size_t uartStopSend(UARTDriver *uartp);
+  size_t uartStopSendI(UARTDriver *uartp);
   void uartStartReceive(UARTDriver *uartp, size_t n, void *rxbuf);
-  void uartStopReceive(UARTDriver *uartp);
+  void uartStartReceiveI(UARTDriver *uartp, size_t n, void *rxbuf);
+  size_t uartStopReceive(UARTDriver *uartp);
+  size_t uartStopReceiveI(UARTDriver *uartp);
 #ifdef __cplusplus
 }
 #endif
diff --git a/os/hal/platforms/STM32/uart_lld.c b/os/hal/platforms/STM32/uart_lld.c
index 7974f74fa..f06ab2504 100644
--- a/os/hal/platforms/STM32/uart_lld.c
+++ b/os/hal/platforms/STM32/uart_lld.c
@@ -522,8 +522,10 @@ void uart_lld_start(UARTDriver *uartp) {
     uartp->ud_dmaccr = STM32_UART_USART1_DMA_PRIORITY << 12;
     if ((uartp->ud_config->uc_cr1 & (USART_CR1_M | USART_CR1_PCE)) == USART_CR1_M)
       uartp->ud_dmaccr |= DMA_CCR1_MSIZE_0 | DMA_CCR1_PSIZE_0;
-    uartp->ud_dmap->channels[uartp->ud_dmarx].CPAR = (uint32_t)&uartp->ud_usart->DR;
-    uartp->ud_dmap->channels[uartp->ud_dmatx].CPAR = (uint32_t)&uartp->ud_usart->DR;
+    dmaChannelSetPeripheral(&uartp->ud_dmap->channels[uartp->ud_dmarx],
+                            &uartp->ud_usart->DR);
+    dmaChannelSetPeripheral(&uartp->ud_dmap->channels[uartp->ud_dmatx],
+                            &uartp->ud_usart->DR);
     uartp->ud_rxbuf = 0;
   }
 
@@ -600,11 +602,15 @@ void uart_lld_start_send(UARTDriver *uartp, size_t n, const void *txbuf) {
  * @note    Stopping a transmission also suppresses the transmission callbacks.
  *
  * @param[in] uartp     pointer to the @p UARTDriver object
+ *
+ * @return              The number of data frames not transmitted by the
+ *                      stopped transmit operation.
  */
-void uart_lld_stop_send(UARTDriver *uartp) {
+size_t uart_lld_stop_send(UARTDriver *uartp) {
 
   dmaDisableChannel(uartp->ud_dmap, uartp->ud_dmatx);
   dmaClearChannel(uartp->ud_dmap, uartp->ud_dmatx);
+  return (size_t)uartp->ud_dmap->channels[uartp->ud_dmatx].CNDTR;
 }
 
 /**
@@ -634,12 +640,18 @@ void uart_lld_start_receive(UARTDriver *uartp, size_t n, void *rxbuf) {
  * @note    Stopping a receive operation also suppresses the receive callbacks.
  *
  * @param[in] uartp     pointer to the @p UARTDriver object
+ *
+ * @return              The number of data frames not received by the
+ *                      stopped receive operation.
  */
-void uart_lld_stop_receive(UARTDriver *uartp) {
+size_t uart_lld_stop_receive(UARTDriver *uartp) {
+  size_t n;
 
   dmaDisableChannel(uartp->ud_dmap, uartp->ud_dmarx);
   dmaClearChannel(uartp->ud_dmap, uartp->ud_dmarx);
+  n = (size_t)uartp->ud_dmap->channels[uartp->ud_dmarx].CNDTR;
   set_rx_idle_loop(uartp);
+  return n;
 }
 
 #endif /* CH_HAL_USE_UART */
diff --git a/os/hal/platforms/STM32/uart_lld.h b/os/hal/platforms/STM32/uart_lld.h
index e0d0851d6..d6927ccdb 100644
--- a/os/hal/platforms/STM32/uart_lld.h
+++ b/os/hal/platforms/STM32/uart_lld.h
@@ -266,9 +266,9 @@ extern "C" {
   void uart_lld_start(UARTDriver *uartp);
   void uart_lld_stop(UARTDriver *uartp);
   void uart_lld_start_send(UARTDriver *uartp, size_t n, const void *txbuf);
-  void uart_lld_stop_send(UARTDriver *uartp);
+  size_t uart_lld_stop_send(UARTDriver *uartp);
   void uart_lld_start_receive(UARTDriver *uartp, size_t n, void *rxbuf);
-  void uart_lld_stop_receive(UARTDriver *uartp);
+  size_t uart_lld_stop_receive(UARTDriver *uartp);
 #ifdef __cplusplus
 }
 #endif
diff --git a/os/hal/src/uart.c b/os/hal/src/uart.c
index 4c1a2a55a..097bd364b 100644
--- a/os/hal/src/uart.c
+++ b/os/hal/src/uart.c
@@ -164,8 +164,13 @@ void uartStartSendI(UARTDriver *uartp, size_t n, const void *txbuf) {
  * @note    Stopping a transmission also suppresses the transmission callbacks.
  *
  * @param[in] uartp     pointer to the @p UARTDriver object
+ *
+ * @return              The number of data frames not transmitted by the
+ *                      stopped transmit operation.
+ * @retval 0            There was no transmit operation in progress.
  */
-void uartStopSend(UARTDriver *uartp) {
+size_t uartStopSend(UARTDriver *uartp) {
+  size_t n;
 
   chDbgCheck(uartp != NULL, "uartStopSend");
 
@@ -175,10 +180,13 @@ void uartStopSend(UARTDriver *uartp) {
               "not active");
 
   if (uartp->ud_txstate == UART_TX_ACTIVE) {
-    uart_lld_stop_send(uartp);
+    n = uart_lld_stop_send(uartp);
     uartp->ud_txstate = UART_TX_IDLE;
   }
+  else
+    n = 0;
   chSysUnlock();
+  return n;
 }
 
 /**
@@ -187,8 +195,12 @@ void uartStopSend(UARTDriver *uartp) {
  * @note    This function has to be invoked from a lock zone.
  *
  * @param[in] uartp     pointer to the @p UARTDriver object
+ *
+ * @return              The number of data frames not transmitted by the
+ *                      stopped transmit operation.
+ * @retval 0            There was no transmit operation in progress.
  */
-void uartStopSendI(UARTDriver *uartp) {
+size_t uartStopSendI(UARTDriver *uartp) {
 
   chDbgCheck(uartp != NULL, "uartStopSendI");
 
@@ -197,9 +209,11 @@ void uartStopSendI(UARTDriver *uartp) {
               "not active");
 
   if (uartp->ud_txstate == UART_TX_ACTIVE) {
-    uart_lld_stop_send(uartp);
+    size_t n = uart_lld_stop_send(uartp);
     uartp->ud_txstate = UART_TX_IDLE;
+    return n;
   }
+  return 0;
 }
 
 /**
@@ -256,8 +270,13 @@ void uartStartReceiveI(UARTDriver *uartp, size_t n, void *rxbuf) {
  * @note    Stopping a receive operation also suppresses the receive callbacks.
  *
  * @param[in] uartp     pointer to the @p UARTDriver object
+ *
+ * @return              The number of data frames not received by the
+ *                      stopped receive operation.
+ * @retval 0            There was no receive operation in progress.
  */
-void uartStopReceive(UARTDriver *uartp) {
+size_t uartStopReceive(UARTDriver *uartp) {
+  size_t n;
 
   chDbgCheck(uartp != NULL, "uartStopReceive");
 
@@ -267,10 +286,13 @@ void uartStopReceive(UARTDriver *uartp) {
               "not active");
 
   if (uartp->ud_rxstate == UART_RX_ACTIVE) {
-    uart_lld_stop_receive(uartp);
+    n = uart_lld_stop_receive(uartp);
     uartp->ud_rxstate = UART_RX_IDLE;
   }
+  else
+    n = 0;
   chSysUnlock();
+  return n;
 }
 
 /**
@@ -279,9 +301,12 @@ void uartStopReceive(UARTDriver *uartp) {
  * @note    This function has to be invoked from a lock zone.
  *
  * @param[in] uartp      pointer to the @p UARTDriver object
+ *
+ * @return              The number of data frames not received by the
+ *                      stopped receive operation.
+ * @retval 0            There was no receive operation in progress.
  */
-void uartStopReceiveI(UARTDriver *uartp) {
-
+size_t uartStopReceiveI(UARTDriver *uartp) {
   chDbgCheck(uartp != NULL, "uartStopReceiveI");
 
   chDbgAssert(uartp->ud_state == UART_READY,
@@ -289,9 +314,11 @@ void uartStopReceiveI(UARTDriver *uartp) {
               "not active");
 
   if (uartp->ud_rxstate == UART_RX_ACTIVE) {
-    uart_lld_stop_receive(uartp);
+    size_t n = uart_lld_stop_receive(uartp);
     uartp->ud_rxstate = UART_RX_IDLE;
+    return n;
   }
+  return 0;
 }
 
 #endif /* CH_HAL_USE_UART */
diff --git a/os/hal/templates/uart_lld.c b/os/hal/templates/uart_lld.c
index 46c04fe8c..b48620a71 100644
--- a/os/hal/templates/uart_lld.c
+++ b/os/hal/templates/uart_lld.c
@@ -97,8 +97,11 @@ void uart_lld_start_send(UARTDriver *uartp, size_t n, const void *txbuf) {
  * @note    Stopping a transmission also suppresses the transmission callbacks.
  *
  * @param[in] uartp      pointer to the @p UARTDriver object
+ *
+ * @return              The number of data frames not transmitted by the
+ *                      stopped transmit operation.
  */
-void uart_lld_stop_send(UARTDriver *uartp) {
+size_t uart_lld_stop_send(UARTDriver *uartp) {
 
 }
 
@@ -120,8 +123,11 @@ void uart_lld_start_receive(UARTDriver *uartp, size_t n, void *rxbuf) {
  * @note    Stopping a receive operation also suppresses the receive callbacks.
  *
  * @param[in] uartp      pointer to the @p UARTDriver object
+ *
+ * @return              The number of data frames not received by the
+ *                      stopped receive operation.
  */
-void uart_lld_stop_receive(UARTDriver *uartp) {
+size_t uart_lld_stop_receive(UARTDriver *uartp) {
 
 }
 
diff --git a/os/hal/templates/uart_lld.h b/os/hal/templates/uart_lld.h
index 2d5c576b3..7a0c37373 100644
--- a/os/hal/templates/uart_lld.h
+++ b/os/hal/templates/uart_lld.h
@@ -107,9 +107,9 @@ extern "C" {
   void uart_lld_start(UARTDriver *uartp);
   void uart_lld_stop(UARTDriver *uartp);
   void uart_lld_start_send(UARTDriver *uartp, size_t n, const void *txbuf);
-  void uart_lld_stop_send(UARTDriver *uartp);
+  size_t uart_lld_stop_send(UARTDriver *uartp);
   void uart_lld_start_receive(UARTDriver *uartp, size_t n, void *rxbuf);
-  void uart_lld_stop_receive(UARTDriver *uartp);
+  size_t uart_lld_stop_receive(UARTDriver *uartp);
 #ifdef __cplusplus
 }
 #endif
diff --git a/readme.txt b/readme.txt
index 0fe86244b..aded26ed0 100644
--- a/readme.txt
+++ b/readme.txt
@@ -68,6 +68,8 @@
   2.0.3).
 - FIX: Fixed a documentation error regarding the ADC driver function
   adcStartConversion() (bug 3039890)(backported to 2.0.3).
+- NEW: Added to the UART driver the capability to return the number of
+  not yet transferred frames when stopping an operation.
 - NEW: Added more compile-time checks to the various STM32 device drivers.
 - NEW: Added a simple STM32 ADC demo under ./testhal/STM32/ADC.
 - NEW: Added a simple STM32 CAN demo under ./testhal/STM32/CAN.
diff --git a/testhal/STM32/UART/main.c b/testhal/STM32/UART/main.c
index 1ba3ec336..ef862a981 100644
--- a/testhal/STM32/UART/main.c
+++ b/testhal/STM32/UART/main.c
@@ -25,7 +25,9 @@ static VirtualTimer vt1, vt2;
 static void restart(void *p) {
 
   (void)p;
-  uartStartSend(&UARTD2, 14, "Hello World!\r\n");
+  chSysLockFromIsr();
+  uartStartSendI(&UARTD2, 14, "Hello World!\r\n");
+  chSysUnlockFromIsr();
 }
 
 static void ledoff(void *p) {
@@ -50,6 +52,8 @@ static void txend2(void) {
 
   palSetPad(IOPORT3, GPIOC_LED);
   chSysLockFromIsr();
+  if (chVTIsArmedI(&vt1))
+    chVTResetI(&vt1);
   chVTSetI(&vt1, MS2ST(5000), restart, NULL);
   chSysUnlockFromIsr();
 }