diff --git a/src/FSMCIO.cpp b/src/FSMCIO.cpp
index 2965c54..6e1bd9c 100644
--- a/src/FSMCIO.cpp
+++ b/src/FSMCIO.cpp
@@ -4,6 +4,8 @@
 #define STM32F412Zx
 #endif
 
+#ifdef STM32F412Zx
+
 #include "FSMCIO.h"
 #include "dma.h"
 
@@ -135,3 +137,5 @@ void FSMCIO::startSend(const void *txBuffer, uint32_t txSize, PVoidCallback done
 }
 
 } // namespace codal
+
+#endif
\ No newline at end of file
diff --git a/src/STMLowLevelTimer.cpp b/src/STMLowLevelTimer.cpp
index 770a82d..18f99db 100644
--- a/src/STMLowLevelTimer.cpp
+++ b/src/STMLowLevelTimer.cpp
@@ -39,7 +39,8 @@ void timer_irq_handler(uint8_t index)
         __HAL_TIM_CLEAR_IT(timHandle, TIM_IT_CC4);
     }
 
-    instances[index]->timer_pointer(channel_bitmsk);
+    if (instances[index]->timer_pointer)
+        instances[index]->timer_pointer(channel_bitmsk);
 }
 
 extern "C" void TIM1_IRQHandler()
@@ -70,6 +71,7 @@ STMLowLevelTimer::STMLowLevelTimer(TIM_TypeDef* timer, uint8_t irqn) : LowLevelT
     this->timer_instance = timer;
     this->irqN = irqn;
     memset(&TimHandle, 0, sizeof(TIM_HandleTypeDef));
+    disableIRQ();
 
     disableIRQ(); // otherwise it might hit us while we're initializing
 
diff --git a/src/USB.cpp b/src/USB.cpp
index dff0d41..1af3057 100644
--- a/src/USB.cpp
+++ b/src/USB.cpp
@@ -88,7 +88,7 @@ void usb_configure(uint8_t numEndpoints)
 
 #ifdef USB
     __HAL_RCC_USB_CLK_ENABLE();
-    irqn = USB_IRQn;
+    irqn = USB_HP_CAN1_TX_IRQn;
     pcd.Init.speed = PCD_SPEED_FULL;
 #else  /* USB_OTG_FS */
     __HAL_RCC_USB_OTG_FS_CLK_ENABLE();
@@ -112,8 +112,14 @@ void usb_configure(uint8_t numEndpoints)
         HAL_PCDEx_SetTxFiFo(&pcd, i, FIFO_EP_WORDS);
 #endif /* USB */
 
+    // USB_HP_CAN1_TX_IRQn
+    // USB_LP_CAN1_RX_IRQn
+
+NVIC_SetPriority(USB_LP_CAN1_RX0_IRQn, 5);
+    NVIC_EnableIRQ(USB_LP_CAN1_RX0_IRQn);
     NVIC_SetPriority(irqn, 5);
     NVIC_EnableIRQ(irqn);
+
 }
 
 #if 0
@@ -150,6 +156,8 @@ static UsbEndpointOut *findOutEp(int ep)
 
 extern "C"
 {
+    void USB_LP_IRQHandler(void) { HAL_PCD_IRQHandler(&pcd); }
+    void USB_HP_IRQHandler(void) { HAL_PCD_IRQHandler(&pcd); }
 
     void OTG_FS_IRQHandler(void) { HAL_PCD_IRQHandler(&pcd); }
 
@@ -337,25 +345,33 @@ static void writeEP(uint8_t *data, uint8_t ep, int len)
 {
     usb_assert(len <= USB_MAX_PKT_SIZE);
     uint32_t len32b = (len + 3) / 4;
-
+#ifndef USB
     DBG("%d write space: %d words", (int)codal::system_timer_current_time_us(),
         USBx_INEP(ep)->DTXFSTS & USB_OTG_DTXFSTS_INEPTFSAV);
 
     while ((USBx_INEP(ep)->DTXFSTS & USB_OTG_DTXFSTS_INEPTFSAV) < len32b)
         ;
 
-    DBG("write: %p len=%d at IN %d", data, len, ep);
+     DBG("write: %p len=%d at IN %d", data, len, ep);
     CHK(HAL_PCD_EP_Transmit(&pcd, ep | 0x80, data, len));
 
     if (len)
         CHK(USB_WritePacket(pcd.Instance, data, ep, len, 0));
+#else
+    DBG("write: %p len=%d at IN %d", data, len, ep);
+    CHK(HAL_PCD_EP_Transmit(&pcd, ep | 0x80, data, len));
+
+    if (len)
+        CHK(USB_WritePacket(pcd.Instance, data, ep, len));
+#endif
 
+#ifndef USB
     USBx_DEVICE->DIEPEMPMSK &= ~0x1U << ep;
 
     while (!(USB_ReadDevInEPInterrupt(pcd.Instance, ep) & USB_OTG_DIEPINT_XFRC))
         ;
     CLEAR_IN_EP_INTR(ep, USB_OTG_DIEPINT_XFRC);
-
+#endif
     DBG("%d write done, ctl=%p", (int)codal::system_timer_current_time_us(),
         USBx_OUTEP(0)->DOEPCTL);
 
diff --git a/src/ZSingleWireSerial.cpp b/src/ZSingleWireSerial.cpp
index 40fd3a1..2ffc22a 100644
--- a/src/ZSingleWireSerial.cpp
+++ b/src/ZSingleWireSerial.cpp
@@ -30,6 +30,7 @@ static ZSingleWireSerial *instances[4];
 
 static int enable_clock(uint32_t instance)
 {
+    DMESG("CLK EN");
     switch (instance)
     {
     case USART1_BASE:
@@ -42,6 +43,11 @@ static int enable_clock(uint32_t instance)
         NVIC_SetPriority(USART2_IRQn, 2);
         NVIC_EnableIRQ(USART2_IRQn);
         return HAL_RCC_GetPCLK1Freq();
+    case USART3_BASE:
+        __HAL_RCC_USART3_CLK_ENABLE();
+        DMESG("PCLK1 %d", HAL_RCC_GetPCLK1Freq());
+        NVIC_EnableIRQ(USART3_IRQn);
+        return HAL_RCC_GetPCLK1Freq();
 #ifdef USART6_BASE
     case USART6_BASE:
         __HAL_RCC_USART6_CLK_ENABLE();
@@ -116,6 +122,7 @@ extern "C" void HAL_UART_ErrorCallback(UART_HandleTypeDef *hspi)
 
 DEFIRQ(USART1_IRQHandler, USART1_BASE)
 DEFIRQ(USART2_IRQHandler, USART2_BASE)
+DEFIRQ(USART3_IRQHandler, USART3_BASE)
 #ifdef USART6_BASE
 DEFIRQ(USART6_IRQHandler, USART6_BASE)
 #endif
@@ -197,8 +204,9 @@ int ZSingleWireSerial::configureTx(int enable)
     if (enable && !(status & TX_CONFIGURED))
     {
         uint8_t pin = (uint8_t)p.name;
-        pin_mode(pin, PullNone);
+        // pin_mode(pin, PullNone);
         pin_function(pin, pinmap_function(pin, PinMap_UART_TX));
+        pin_mode(pin,PullUp);
         uart.Init.Mode = UART_MODE_TX;
         HAL_HalfDuplex_Init(&uart);
         status |= TX_CONFIGURED;
@@ -291,6 +299,7 @@ int ZSingleWireSerial::sendDMA(uint8_t* data, int len)
     this->bufLen = len;
 
     int res = HAL_UART_Transmit_DMA(&uart, data, len);
+    DMESG("TXDMA RES %d ",res);
 
     CODAL_ASSERT(res == HAL_OK, DEVICE_HARDWARE_CONFIGURATION_ERROR);
 
@@ -326,8 +335,11 @@ int ZSingleWireSerial::getBytesReceived()
 {
     if (!(status & RX_CONFIGURED))
         return DEVICE_INVALID_PARAMETER;
-
+#ifdef STM32F1
+    return hdma_rx.Instance->CNDTR;
+#else
     return hdma_rx.Instance->NDTR;
+#endif
 }
 
 int ZSingleWireSerial::getBytesTransmitted()
@@ -335,7 +347,11 @@ int ZSingleWireSerial::getBytesTransmitted()
     if (!(status & TX_CONFIGURED))
         return DEVICE_INVALID_PARAMETER;
 
+#ifdef STM32F1
+    return hdma_tx.Instance->CNDTR;
+#else
     return hdma_tx.Instance->NDTR;
+#endif
 }
 
 int ZSingleWireSerial::sendBreak()
diff --git a/src/codal_target_hal.cpp b/src/codal_target_hal.cpp
index c6b6489..f1befa9 100644
--- a/src/codal_target_hal.cpp
+++ b/src/codal_target_hal.cpp
@@ -55,7 +55,11 @@ int target_random(int max)
     device and in any context. These bits can never be altered by the user.
     The 96-bit unique device identifier can also be read in single bytes/half-words/words in different ways and then be concatenated using a custom algorithm.
 */
+#ifdef STM32F1
+#define STM32_UUID ((uint32_t *)0x1FFFF7E8)
+#else
 #define STM32_UUID ((uint32_t *)0x1FFF7A10)
+#endif
 uint64_t target_get_serial()
 {
     // uuid[1] is the wafer number plus the lot number, need to check the uniqueness of this...
diff --git a/src/dma_f1.c b/src/dma_f1.c
index bf3b794..156b5c2 100644
--- a/src/dma_f1.c
+++ b/src/dma_f1.c
@@ -1,8 +1,9 @@
 #include "dma.h"
 #include "CodalDmesg.h"
+#include "ErrorNo.h"
 
 #ifdef STM32F1
-
+#include "stm32f1xx.h"
 #define NUM_STREAMS 7
 #define NUM_DMA 2
 
@@ -61,7 +62,7 @@ MBED_WEAK const DmaMap TheDmaMap[] = //
      {UART4_BASE, DMA_RX, 13},
      {UART4_BASE, DMA_TX, 15},
      {DAC_BASE, DMA_TX, 13},
-#endif     
+#endif
 
      // The end
      {0, 0, 0}};
@@ -71,7 +72,6 @@ static DMA_HandleTypeDef *handles[7 + 5];
 #define HANDLE_IDX(id) (id < 10 ? id - 1 : id - 4)
 static void irq_callback(int id)
 {
-    LOG("DMA irq %d", id);
     id = HANDLE_IDX(id);
     if (handles[id])
         HAL_DMA_IRQHandler(handles[id]);
@@ -97,6 +97,23 @@ void DMA2_Channel4_5_IRQHandler()
     irq_callback(15);
 }
 
+int lookup_dma(uint32_t peripheral, uint8_t rxdx)
+{
+    int id = -1;
+    const DmaMap *map;
+
+    for (map = TheDmaMap; map->peripheral; map++)
+    {
+        if (map->peripheral == peripheral && map->rxdx == rxdx)
+        {
+            id = HANDLE_IDX(map->channel);
+            break;
+        }
+    }
+
+    return id;
+}
+
 int dma_init(uint32_t peripheral, uint8_t rxdx, DMA_HandleTypeDef *obj, int flags)
 {
     memset(obj, 0, sizeof(*obj));
@@ -117,7 +134,7 @@ int dma_init(uint32_t peripheral, uint8_t rxdx, DMA_HandleTypeDef *obj, int flag
         }
     }
 
-    CODAL_ASSERT(map->peripheral);
+    CODAL_ASSERT(map->peripheral, DEVICE_HARDWARE_CONFIGURATION_ERROR);
 
     obj->Instance = streams[id].instance;
 
@@ -150,7 +167,7 @@ int dma_init(uint32_t peripheral, uint8_t rxdx, DMA_HandleTypeDef *obj, int flag
 #endif
 
     int res = HAL_DMA_Init(obj);
-    CODAL_ASSERT(res == HAL_OK);
+    CODAL_ASSERT(res == HAL_OK, DEVICE_HARDWARE_CONFIGURATION_ERROR);
 
     LOG("DMA init %p irq=%d ch=%d str=%d", obj->Instance, streams[id].irqn, map->channel,
         map->stream);
@@ -160,4 +177,15 @@ int dma_init(uint32_t peripheral, uint8_t rxdx, DMA_HandleTypeDef *obj, int flag
     return 0;
 }
 
+void dma_set_irq_priority(uint32_t peripheral, uint8_t rxdx, int priority)
+{
+    int id = lookup_dma(peripheral, rxdx);
+
+    CODAL_ASSERT(id != -1, DEVICE_HARDWARE_CONFIGURATION_ERROR);
+
+    NVIC_DisableIRQ(streams[id].irqn);
+    NVIC_SetPriority(streams[id].irqn, priority);
+    NVIC_EnableIRQ(streams[id].irqn);
+}
+
 #endif
\ No newline at end of file
diff --git a/src/pinmap.c b/src/pinmap.c
index c83934d..6430f1c 100644
--- a/src/pinmap.c
+++ b/src/pinmap.c
@@ -30,6 +30,7 @@
 #include "pinmap.h"
 //#include "PortNames.h"
 #include "pin_device.h"
+#include "CodalDmesg.h"
 
 #define error MBED_ERROR