diff --git a/hw/usb_interface/ch552_fw/include/debug.h b/hw/usb_interface/ch552_fw/include/debug.h
index ee99780..842e5b6 100644
--- a/hw/usb_interface/ch552_fw/include/debug.h
+++ b/hw/usb_interface/ch552_fw/include/debug.h
@@ -151,6 +151,7 @@ inline void UART1Setup()
                   // Should correct for rounding in SBAUD1 calculation
     SBAUD1 = 256 - FREQ_SYS/16/UART1_BAUD; // Calculation for Fast mode
     IE_UART1 = 1; // Enable UART1 interrupt
+    IP_EX = bIP_UART1; // Serial port IRQ has high priority
 }
 
 /*******************************************************************************
diff --git a/hw/usb_interface/ch552_fw/main.c b/hw/usb_interface/ch552_fw/main.c
index e8dd4c7..bdc422c 100644
--- a/hw/usb_interface/ch552_fw/main.c
+++ b/hw/usb_interface/ch552_fw/main.c
@@ -55,10 +55,10 @@ USB_SETUP_REQ SetupReqBuf = { 0 };    // Temporary Setup package
 #define TKEYCTRL_EPIN_ADDR             0x84              // TKEYCTRL Endpoint IN Address
 #define TKEYCTRL_EPIN_SIZE             MAX_PACKET_SIZE   // TKEYCTRL Endpoint IN Size
 
-#define CDC_CTRL_FS_BINTERVAL          0xFF              // Gives 32 ms polling interval at Full Speed
-#define CDC_DATA_FS_BINTERVAL          10                // Gives 8 ms polling interval at Full Speed
-#define HID_FS_BINTERVAL               10                // Gives 8 ms polling interval at Full Speed
-#define TKEYCTRL_FS_BINTERVAL          10                // Gives 8 ms polling interval at Full Speed
+#define CDC_CTRL_FS_BINTERVAL          32                // Gives 32 ms polling interval at Full Speed for interrupt transfers
+#define CDC_DATA_FS_BINTERVAL          0                 // bInterval is ignored for BULK transfers
+#define HID_FS_BINTERVAL               2                 // Gives 2 ms polling interval at Full Speed for interrupt transfers
+#define TKEYCTRL_FS_BINTERVAL          2                 // Gives 2 ms polling interval at Full Speed for interrupt transfers
 
 #define CFGDESC_SIZE                   139U              // Size of CfgDesc
 #define NUM_INTERFACES                 4                 // Number of interfaces