diff --git a/hw/bsp/stm32f407g_disc1/board.mk b/hw/bsp/stm32f407g_disc1/board.mk
index 50990de87..24efea1ac 100644
--- a/hw/bsp/stm32f407g_disc1/board.mk
+++ b/hw/bsp/stm32f407g_disc1/board.mk
@@ -1,4 +1,5 @@
 CFLAGS = \
+	-DHSE_VALUE=8000000 \
 	-DCFG_TUSB_MCU=OPT_MCU_STM32F4 \
 	-DSTM32F407xx \
 	-mthumb \
diff --git a/hw/bsp/stm32f407g_disc1/board_stm32f407g_disc1.c b/hw/bsp/stm32f407g_disc1/board_stm32f407g_disc1.c
index 3c1ebc11f..f08cecac8 100644
--- a/hw/bsp/stm32f407g_disc1/board_stm32f407g_disc1.c
+++ b/hw/bsp/stm32f407g_disc1/board_stm32f407g_disc1.c
@@ -49,38 +49,52 @@
 
 void board_init(void)
 {
-
-  // Systick init
-#if CFG_TUSB_OS  == OPT_OS_NONE
-  // Tick init, samd SystemCoreClock may not correct
-  SysTick_Config(SystemCoreClock / 1000);
-#endif
-
   // Init the LED on PD14
   RCC->AHB1ENR |= RCC_AHB1ENR_GPIODEN;
   GPIOD->MODER |= GPIO_MODER_MODE14_0;
 
   // USB Clock init
-  // PLL input- 16 MHz (HSI clock)
-  // VCO input- 1 to 2 MHz (2 MHz, M = 8)
+  // PLL input- 8 MHz (External oscillator clock; HSI clock tolerance isn't
+  // tight enough- 1%, need 0.25%)
+  // VCO input- 1 to 2 MHz (2 MHz, M = 4)
   // VCO output- 100 to 432 MHz (144 MHz, N = 72)
-  // Main PLL out- <= 180 MHz (18 MHz, P = 8, not used; HSI used as system clk.)
+  // Main PLL out- <= 180 MHz (18 MHz, P = 3- divides by 8)
   // USB PLL out- 48 MHz (Q = 3)
-  RCC->PLLCFGR = (3 << RCC_PLLCFGR_PLLQ_Pos) | (8 << RCC_PLLCFGR_PLLP_Pos) \
-    | (72 << RCC_PLLCFGR_PLLN_Pos) |  (8 << RCC_PLLCFGR_PLLM_Pos);
+  RCC->PLLCFGR = RCC_PLLCFGR_PLLSRC_HSE | (3 << RCC_PLLCFGR_PLLQ_Pos) | \
+    (3 << RCC_PLLCFGR_PLLP_Pos) | (72 << RCC_PLLCFGR_PLLN_Pos) | \
+    (4 << RCC_PLLCFGR_PLLM_Pos);
+
+  // Wait for external clock to become ready
+  RCC->CR |= RCC_CR_HSEON;
+  while(!(RCC->CR & RCC_CR_HSERDY_Msk));
+
+  // Wait for PLL to become ready
   RCC->CR |= RCC_CR_PLLON;
+  while(!(RCC->CR & RCC_CR_PLLRDY_Msk));
+
+  // Switch clocks!
+  RCC->CFGR |= RCC_CFGR_SW_1;
+
+  // Notify runtime of frequency change.
+  SystemCoreClockUpdate();
+  // Systick init
+  #if CFG_TUSB_OS  == OPT_OS_NONE
+    SysTick_Config(SystemCoreClock / 1000);
+  #endif
+
   RCC->AHB2ENR |= RCC_AHB2ENR_OTGFSEN;
 
   // USB Pin Init
   // PA10- ID, PA11- DM, PA12- DP
   // PC0- Power on
-  GPIOD->MODER |= GPIO_MODER_MODE10_1 | GPIO_MODER_MODE11_1 | GPIO_MODER_MODE12_1;
-  GPIOA->AFR[1] |= (10 << GPIO_AFRH_AFSEL10_Pos) | (10 << GPIO_AFRH_AFSEL11_Pos) | (10 << GPIO_AFRH_AFSEL12_Pos);
+  RCC->AHB1ENR |= RCC_AHB1ENR_GPIOAEN;
+  GPIOD->MODER |= GPIO_MODER_MODE10_1 | GPIO_MODER_MODE11_1 | \
+    GPIO_MODER_MODE12_1;
+  GPIOA->AFR[1] |= (10 << GPIO_AFRH_AFSEL10_Pos) | \
+    (10 << GPIO_AFRH_AFSEL11_Pos) | (10 << GPIO_AFRH_AFSEL12_Pos);
 }
 
 
-
-
 void board_led_control(bool state)
 {
   if (!state) {
diff --git a/src/portable/stm/stm32f4/dcd_stm32f4.c b/src/portable/stm/stm32f4/dcd_stm32f4.c
index 3ec3c9e06..8aa95ac1d 100644
--- a/src/portable/stm/stm32f4/dcd_stm32f4.c
+++ b/src/portable/stm/stm32f4/dcd_stm32f4.c
@@ -71,17 +71,21 @@ bool dcd_init (uint8_t rhport)
 
 void dcd_int_enable (uint8_t rhport)
 {
-
+  (void) rhport;
+  NVIC_EnableIRQ(OTG_FS_IRQn);
 }
+
 void dcd_int_disable (uint8_t rhport)
 {
-
+  (void) rhport;
+  NVIC_DisableIRQ(OTG_FS_IRQn);
 }
 
 void dcd_connect (uint8_t rhport)
 {
 
 }
+
 void dcd_disconnect (uint8_t rhport)
 {