diff --git a/targets/TARGET_Maxim/TARGET_MAX32630/PeripheralPins.c b/targets/TARGET_Maxim/TARGET_MAX32630/PeripheralPins.c
index ccb27f26937..2b5bb0f5ab3 100644
--- a/targets/TARGET_Maxim/TARGET_MAX32630/PeripheralPins.c
+++ b/targets/TARGET_Maxim/TARGET_MAX32630/PeripheralPins.c
@@ -100,26 +100,26 @@ const PinMap PinMap_UART_RX[] = {
 };
 
 const PinMap PinMap_UART_CTS[] = {
-    { P0_2, UART_0, (int)&((pin_function_t){&MXC_IOMAN->uart0_req, &MXC_IOMAN->uart0_ack, ((uint32_t)IOMAN_MAP_A | MXC_F_IOMAN_UART0_REQ_CTS_IO_REQ), (MXC_F_IOMAN_UART0_ACK_CTS_MAP | MXC_F_IOMAN_UART0_ACK_CTS_IO_ACK)}) },
-    { P2_2, UART_1, (int)&((pin_function_t){&MXC_IOMAN->uart1_req, &MXC_IOMAN->uart1_ack, ((uint32_t)IOMAN_MAP_A | MXC_F_IOMAN_UART1_REQ_CTS_IO_REQ), (MXC_F_IOMAN_UART1_ACK_CTS_MAP | MXC_F_IOMAN_UART1_ACK_CTS_IO_ACK)}) },
-    { P3_2, UART_2, (int)&((pin_function_t){&MXC_IOMAN->uart2_req, &MXC_IOMAN->uart2_ack, ((uint32_t)IOMAN_MAP_A | MXC_F_IOMAN_UART2_REQ_CTS_IO_REQ), (MXC_F_IOMAN_UART2_ACK_CTS_MAP | MXC_F_IOMAN_UART2_ACK_CTS_IO_ACK)}) },
-    { P5_5, UART_3, (int)&((pin_function_t){&MXC_IOMAN->uart3_req, &MXC_IOMAN->uart3_ack, ((uint32_t)IOMAN_MAP_A | MXC_F_IOMAN_UART3_REQ_CTS_IO_REQ), (MXC_F_IOMAN_UART3_ACK_CTS_MAP | MXC_F_IOMAN_UART3_ACK_CTS_IO_ACK)}) },
-    { P0_3, UART_0, (int)&((pin_function_t){&MXC_IOMAN->uart0_req, &MXC_IOMAN->uart0_ack, ((uint32_t)IOMAN_MAP_B | MXC_F_IOMAN_UART0_REQ_CTS_IO_REQ), (MXC_F_IOMAN_UART0_ACK_CTS_MAP | MXC_F_IOMAN_UART0_ACK_CTS_IO_ACK)}) },
-    { P2_3, UART_1, (int)&((pin_function_t){&MXC_IOMAN->uart1_req, &MXC_IOMAN->uart1_ack, ((uint32_t)IOMAN_MAP_B | MXC_F_IOMAN_UART1_REQ_CTS_IO_REQ), (MXC_F_IOMAN_UART1_ACK_CTS_MAP | MXC_F_IOMAN_UART1_ACK_CTS_IO_ACK)}) },
-    { P3_3, UART_2, (int)&((pin_function_t){&MXC_IOMAN->uart2_req, &MXC_IOMAN->uart2_ack, ((uint32_t)IOMAN_MAP_B | MXC_F_IOMAN_UART2_REQ_CTS_IO_REQ), (MXC_F_IOMAN_UART2_ACK_CTS_MAP | MXC_F_IOMAN_UART2_ACK_CTS_IO_ACK)}) },
-    { P5_6, UART_3, (int)&((pin_function_t){&MXC_IOMAN->uart3_req, &MXC_IOMAN->uart3_ack, ((uint32_t)IOMAN_MAP_B | MXC_F_IOMAN_UART3_REQ_CTS_IO_REQ), (MXC_F_IOMAN_UART3_ACK_CTS_MAP | MXC_F_IOMAN_UART3_ACK_CTS_IO_ACK)}) },
+    { P0_2, UART_0, (int)&((pin_function_t){&MXC_IOMAN->uart0_req, &MXC_IOMAN->uart0_ack, ((uint32_t)(IOMAN_MAP_A << MXC_F_IOMAN_UART0_REQ_CTS_MAP_POS) | MXC_F_IOMAN_UART0_REQ_CTS_IO_REQ), (MXC_F_IOMAN_UART0_ACK_CTS_MAP | MXC_F_IOMAN_UART0_ACK_CTS_IO_ACK)}) },
+    { P2_2, UART_1, (int)&((pin_function_t){&MXC_IOMAN->uart1_req, &MXC_IOMAN->uart1_ack, ((uint32_t)(IOMAN_MAP_A << MXC_F_IOMAN_UART1_REQ_CTS_MAP_POS) | MXC_F_IOMAN_UART1_REQ_CTS_IO_REQ), (MXC_F_IOMAN_UART1_ACK_CTS_MAP | MXC_F_IOMAN_UART1_ACK_CTS_IO_ACK)}) },
+    { P3_2, UART_2, (int)&((pin_function_t){&MXC_IOMAN->uart2_req, &MXC_IOMAN->uart2_ack, ((uint32_t)(IOMAN_MAP_A << MXC_F_IOMAN_UART2_REQ_CTS_MAP_POS) | MXC_F_IOMAN_UART2_REQ_CTS_IO_REQ), (MXC_F_IOMAN_UART2_ACK_CTS_MAP | MXC_F_IOMAN_UART2_ACK_CTS_IO_ACK)}) },
+    { P5_5, UART_3, (int)&((pin_function_t){&MXC_IOMAN->uart3_req, &MXC_IOMAN->uart3_ack, ((uint32_t)(IOMAN_MAP_A << MXC_F_IOMAN_UART3_REQ_CTS_MAP_POS) | MXC_F_IOMAN_UART3_REQ_CTS_IO_REQ), (MXC_F_IOMAN_UART3_ACK_CTS_MAP | MXC_F_IOMAN_UART3_ACK_CTS_IO_ACK)}) },
+    { P0_3, UART_0, (int)&((pin_function_t){&MXC_IOMAN->uart0_req, &MXC_IOMAN->uart0_ack, ((uint32_t)(IOMAN_MAP_B << MXC_F_IOMAN_UART0_REQ_CTS_MAP_POS) | MXC_F_IOMAN_UART0_REQ_CTS_IO_REQ), (MXC_F_IOMAN_UART0_ACK_CTS_MAP | MXC_F_IOMAN_UART0_ACK_CTS_IO_ACK)}) },
+    { P2_3, UART_1, (int)&((pin_function_t){&MXC_IOMAN->uart1_req, &MXC_IOMAN->uart1_ack, ((uint32_t)(IOMAN_MAP_B << MXC_F_IOMAN_UART1_REQ_CTS_MAP_POS) | MXC_F_IOMAN_UART1_REQ_CTS_IO_REQ), (MXC_F_IOMAN_UART1_ACK_CTS_MAP | MXC_F_IOMAN_UART1_ACK_CTS_IO_ACK)}) },
+    { P3_3, UART_2, (int)&((pin_function_t){&MXC_IOMAN->uart2_req, &MXC_IOMAN->uart2_ack, ((uint32_t)(IOMAN_MAP_B << MXC_F_IOMAN_UART2_REQ_CTS_MAP_POS) | MXC_F_IOMAN_UART2_REQ_CTS_IO_REQ), (MXC_F_IOMAN_UART2_ACK_CTS_MAP | MXC_F_IOMAN_UART2_ACK_CTS_IO_ACK)}) },
+    { P5_6, UART_3, (int)&((pin_function_t){&MXC_IOMAN->uart3_req, &MXC_IOMAN->uart3_ack, ((uint32_t)(IOMAN_MAP_B << MXC_F_IOMAN_UART3_REQ_CTS_MAP_POS) | MXC_F_IOMAN_UART3_REQ_CTS_IO_REQ), (MXC_F_IOMAN_UART3_ACK_CTS_MAP | MXC_F_IOMAN_UART3_ACK_CTS_IO_ACK)}) },
     { NC,   NC,     0 }
 };
 
 const PinMap PinMap_UART_RTS[] = {
-    { P0_3, UART_0, (int)&((pin_function_t){&MXC_IOMAN->uart0_req, &MXC_IOMAN->uart0_ack, ((uint32_t)IOMAN_MAP_A | MXC_F_IOMAN_UART0_REQ_RTS_IO_REQ), (MXC_F_IOMAN_UART0_ACK_RTS_MAP | MXC_F_IOMAN_UART0_ACK_RTS_IO_ACK)}) },
-    { P2_3, UART_1, (int)&((pin_function_t){&MXC_IOMAN->uart1_req, &MXC_IOMAN->uart1_ack, ((uint32_t)IOMAN_MAP_A | MXC_F_IOMAN_UART1_REQ_RTS_IO_REQ), (MXC_F_IOMAN_UART1_ACK_RTS_MAP | MXC_F_IOMAN_UART1_ACK_RTS_IO_ACK)}) },
-    { P3_3, UART_2, (int)&((pin_function_t){&MXC_IOMAN->uart2_req, &MXC_IOMAN->uart2_ack, ((uint32_t)IOMAN_MAP_A | MXC_F_IOMAN_UART2_REQ_RTS_IO_REQ), (MXC_F_IOMAN_UART2_ACK_RTS_MAP | MXC_F_IOMAN_UART2_ACK_RTS_IO_ACK)}) },
-    { P5_6, UART_3, (int)&((pin_function_t){&MXC_IOMAN->uart3_req, &MXC_IOMAN->uart3_ack, ((uint32_t)IOMAN_MAP_A | MXC_F_IOMAN_UART3_REQ_RTS_IO_REQ), (MXC_F_IOMAN_UART3_ACK_RTS_MAP | MXC_F_IOMAN_UART3_ACK_RTS_IO_ACK)}) },
-    { P0_2, UART_0, (int)&((pin_function_t){&MXC_IOMAN->uart0_req, &MXC_IOMAN->uart0_ack, ((uint32_t)IOMAN_MAP_B | MXC_F_IOMAN_UART0_REQ_RTS_IO_REQ), (MXC_F_IOMAN_UART0_ACK_RTS_MAP | MXC_F_IOMAN_UART0_ACK_RTS_IO_ACK)}) },
-    { P2_2, UART_1, (int)&((pin_function_t){&MXC_IOMAN->uart1_req, &MXC_IOMAN->uart1_ack, ((uint32_t)IOMAN_MAP_B | MXC_F_IOMAN_UART1_REQ_RTS_IO_REQ), (MXC_F_IOMAN_UART1_ACK_RTS_MAP | MXC_F_IOMAN_UART1_ACK_RTS_IO_ACK)}) },
-    { P3_2, UART_2, (int)&((pin_function_t){&MXC_IOMAN->uart2_req, &MXC_IOMAN->uart2_ack, ((uint32_t)IOMAN_MAP_B | MXC_F_IOMAN_UART2_REQ_RTS_IO_REQ), (MXC_F_IOMAN_UART2_ACK_RTS_MAP | MXC_F_IOMAN_UART2_ACK_RTS_IO_ACK)}) },
-    { P5_5, UART_3, (int)&((pin_function_t){&MXC_IOMAN->uart3_req, &MXC_IOMAN->uart3_ack, ((uint32_t)IOMAN_MAP_B | MXC_F_IOMAN_UART3_REQ_RTS_IO_REQ), (MXC_F_IOMAN_UART3_ACK_RTS_MAP | MXC_F_IOMAN_UART3_ACK_RTS_IO_ACK)}) },
+    { P0_3, UART_0, (int)&((pin_function_t){&MXC_IOMAN->uart0_req, &MXC_IOMAN->uart0_ack, ((uint32_t)(IOMAN_MAP_A << MXC_F_IOMAN_UART0_REQ_RTS_MAP_POS) | MXC_F_IOMAN_UART0_REQ_RTS_IO_REQ), (MXC_F_IOMAN_UART0_ACK_RTS_MAP | MXC_F_IOMAN_UART0_ACK_RTS_IO_ACK)}) },
+    { P2_3, UART_1, (int)&((pin_function_t){&MXC_IOMAN->uart1_req, &MXC_IOMAN->uart1_ack, ((uint32_t)(IOMAN_MAP_A << MXC_F_IOMAN_UART1_REQ_RTS_MAP_POS) | MXC_F_IOMAN_UART1_REQ_RTS_IO_REQ), (MXC_F_IOMAN_UART1_ACK_RTS_MAP | MXC_F_IOMAN_UART1_ACK_RTS_IO_ACK)}) },
+    { P3_3, UART_2, (int)&((pin_function_t){&MXC_IOMAN->uart2_req, &MXC_IOMAN->uart2_ack, ((uint32_t)(IOMAN_MAP_A << MXC_F_IOMAN_UART2_REQ_RTS_MAP_POS) | MXC_F_IOMAN_UART2_REQ_RTS_IO_REQ), (MXC_F_IOMAN_UART2_ACK_RTS_MAP | MXC_F_IOMAN_UART2_ACK_RTS_IO_ACK)}) },
+    { P5_6, UART_3, (int)&((pin_function_t){&MXC_IOMAN->uart3_req, &MXC_IOMAN->uart3_ack, ((uint32_t)(IOMAN_MAP_A << MXC_F_IOMAN_UART3_REQ_RTS_MAP_POS) | MXC_F_IOMAN_UART3_REQ_RTS_IO_REQ), (MXC_F_IOMAN_UART3_ACK_RTS_MAP | MXC_F_IOMAN_UART3_ACK_RTS_IO_ACK)}) },
+    { P0_2, UART_0, (int)&((pin_function_t){&MXC_IOMAN->uart0_req, &MXC_IOMAN->uart0_ack, ((uint32_t)(IOMAN_MAP_B << MXC_F_IOMAN_UART0_REQ_RTS_MAP_POS) | MXC_F_IOMAN_UART0_REQ_RTS_IO_REQ), (MXC_F_IOMAN_UART0_ACK_RTS_MAP | MXC_F_IOMAN_UART0_ACK_RTS_IO_ACK)}) },
+    { P2_2, UART_1, (int)&((pin_function_t){&MXC_IOMAN->uart1_req, &MXC_IOMAN->uart1_ack, ((uint32_t)(IOMAN_MAP_B << MXC_F_IOMAN_UART1_REQ_RTS_MAP_POS) | MXC_F_IOMAN_UART1_REQ_RTS_IO_REQ), (MXC_F_IOMAN_UART1_ACK_RTS_MAP | MXC_F_IOMAN_UART1_ACK_RTS_IO_ACK)}) },
+    { P3_2, UART_2, (int)&((pin_function_t){&MXC_IOMAN->uart2_req, &MXC_IOMAN->uart2_ack, ((uint32_t)(IOMAN_MAP_B << MXC_F_IOMAN_UART2_REQ_RTS_MAP_POS) | MXC_F_IOMAN_UART2_REQ_RTS_IO_REQ), (MXC_F_IOMAN_UART2_ACK_RTS_MAP | MXC_F_IOMAN_UART2_ACK_RTS_IO_ACK)}) },
+    { P5_5, UART_3, (int)&((pin_function_t){&MXC_IOMAN->uart3_req, &MXC_IOMAN->uart3_ack, ((uint32_t)(IOMAN_MAP_B << MXC_F_IOMAN_UART3_REQ_RTS_MAP_POS) | MXC_F_IOMAN_UART3_REQ_RTS_IO_REQ), (MXC_F_IOMAN_UART3_ACK_RTS_MAP | MXC_F_IOMAN_UART3_ACK_RTS_IO_ACK)}) },
     { NC,   NC,     0 }
 };
 
diff --git a/targets/TARGET_Maxim/TARGET_MAX32630/serial_api.c b/targets/TARGET_Maxim/TARGET_MAX32630/serial_api.c
index 543dfa7cda6..c7dcb6dc80b 100644
--- a/targets/TARGET_Maxim/TARGET_MAX32630/serial_api.c
+++ b/targets/TARGET_Maxim/TARGET_MAX32630/serial_api.c
@@ -180,6 +180,10 @@ void serial_format(serial_t *obj, int data_bits, SerialParity parity, int stop_b
 //******************************************************************************
 void uart_handler(serial_t *obj)
 {
+    // clear interrupts
+    volatile uint32_t flags = obj->uart->intfl;
+    obj->uart->intfl = flags;
+
     if (obj && obj->id) {
         irq_handler(obj->id, RxIrq);
     }
@@ -200,6 +204,9 @@ void serial_irq_handler(serial_t *obj, uart_irq_handler handler, uint32_t id)
 //******************************************************************************
 void serial_irq_set(serial_t *obj, SerialIrq irq, uint32_t enable)
 {
+    MBED_ASSERT(obj->index < MXC_CFG_UART_INSTANCES);
+    objs[obj->index] = obj;
+
     switch (obj->index) {
         case 0:
             NVIC_SetVector(UART0_IRQn, (uint32_t)uart0_handler);