diff --git a/stm/Makefile b/stm/Makefile
index 2fecd03bad..2facff81ce 100644
--- a/stm/Makefile
+++ b/stm/Makefile
@@ -105,6 +105,14 @@ SRC_STM = \
 #	usb_hcd.c \
 #	usb_hcd_int.c \
 #	usb_otg.c \
+#	usbh_core.c \
+#	usbh_hcs.c \
+#	usbh_stdreq.c \
+#	usbh_ioreq.c \
+#	usbh_usr.c \
+#	usbh_hid_core.c \
+#	usbh_hid_mouse.c \
+#	usbh_hid_keybd.c \
 
 SRC_CC3K = \
 	cc3000_common.c \
diff --git a/stm/lib/usb_bsp.c b/stm/lib/usb_bsp.c
index c4839bdf96..e88e31db0e 100644
--- a/stm/lib/usb_bsp.c
+++ b/stm/lib/usb_bsp.c
@@ -117,6 +117,17 @@ void USB_OTG_BSP_Init(USB_OTG_CORE_HANDLE *pdev) {
     GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL ;
     GPIO_Init(GPIOA, &GPIO_InitStructure);
 
+    /*
+    // Configure ID pin (only in host mode)
+    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
+    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
+    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN;
+    GPIO_InitStructure.GPIO_OType = GPIO_OType_OD;
+    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP ;
+    GPIO_Init(GPIOA, &GPIO_InitStructure);
+    GPIO_PinAFConfig(GPIOA, GPIO_PinSource10, GPIO_AF_OTG_FS);
+    */
+
     RCC_APB2PeriphClockCmd(RCC_APB2Periph_SYSCFG, ENABLE);
     RCC_AHB2PeriphClockCmd(RCC_AHB2Periph_OTG_FS, ENABLE);
 }
@@ -137,6 +148,84 @@ void USB_OTG_BSP_EnableInterrupt(USB_OTG_CORE_HANDLE *pdev) {
     NVIC_Init(&NVIC_InitStructure);
 }
 
+/**
+* @brief  BSP_Drive_VBUS
+*         Drives the Vbus signal through IO
+* @param  state : VBUS states
+* @retval None
+*/
+
+void USB_OTG_BSP_DriveVBUS(USB_OTG_CORE_HANDLE *pdev, uint8_t state) {
+    //printf("DriveVBUS %p %u\n", pdev, state);
+    /*
+    On-chip 5 V VBUS generation is not supported. For this reason, a charge pump 
+    or, if 5 V are available on the application board, a basic power switch, must 
+    be added externally to drive the 5 V VBUS line. The external charge pump can 
+    be driven by any GPIO output. When the application decides to power on VBUS 
+    using the chosen GPIO, it must also set the port power bit in the host port 
+    control and status register (PPWR bit in OTG_FS_HPRT).
+
+    Bit 12 PPWR: Port power
+    The application uses this field to control power to this port, and the core 
+    clears this bit on an overcurrent condition.
+    */
+#if 0 // not implemented
+#ifndef USE_USB_OTG_HS
+    if (0 == state) {
+        /* DISABLE is needed on output of the Power Switch */
+        GPIO_SetBits(HOST_POWERSW_PORT, HOST_POWERSW_VBUS);
+    } else {
+        /*ENABLE the Power Switch by driving the Enable LOW */
+        GPIO_ResetBits(HOST_POWERSW_PORT, HOST_POWERSW_VBUS);
+    }
+#endif
+#endif
+}
+
+/**
+  * @brief  USB_OTG_BSP_ConfigVBUS
+  *         Configures the IO for the Vbus and OverCurrent
+  * @param  None
+  * @retval None
+  */
+
+void  USB_OTG_BSP_ConfigVBUS(USB_OTG_CORE_HANDLE *pdev) {
+    //printf("ConfigVBUS %p\n", pdev);
+#if 0 // not implemented
+#ifdef USE_USB_OTG_FS   
+  GPIO_InitTypeDef GPIO_InitStructure; 
+  
+#ifdef USE_STM3210C_EVAL
+  RCC_APB2PeriphClockCmd(HOST_POWERSW_PORT_RCC, ENABLE);
+  
+  
+  /* Configure Power Switch Vbus Pin */
+  GPIO_InitStructure.GPIO_Pin = HOST_POWERSW_VBUS;
+  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
+  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
+  GPIO_Init(HOST_POWERSW_PORT, &GPIO_InitStructure);
+#else
+  #ifdef USE_USB_OTG_FS  
+  RCC_AHB1PeriphClockCmd( RCC_AHB1Periph_GPIOH , ENABLE);  
+  
+  GPIO_InitStructure.GPIO_Pin = HOST_POWERSW_VBUS;
+  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
+  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT;
+  GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
+  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL ;
+  GPIO_Init(HOST_POWERSW_PORT,&GPIO_InitStructure);
+  #endif  
+#endif
+
+  /* By Default, DISABLE is needed on output of the Power Switch */
+  GPIO_SetBits(HOST_POWERSW_PORT, HOST_POWERSW_VBUS);
+  
+  USB_OTG_BSP_mDelay(200);   /* Delay is need for stabilising the Vbus Low 
+  in Reset Condition, when Vbus=1 and Reset-button is pressed by user */
+#endif  
+#endif
+}
+
 /**
 * @brief  USB_OTG_BSP_uDelay
 *         This function provides delay time in micro sec
diff --git a/stm/lib/usb_conf.h b/stm/lib/usb_conf.h
index 5e736f91e2..a51a23a84e 100644
--- a/stm/lib/usb_conf.h
+++ b/stm/lib/usb_conf.h
@@ -181,10 +181,65 @@
 /****************** USB OTG MISC CONFIGURATION ********************************/
 #define VBUS_SENSING_ENABLED
 
+/* BEGIN host specific stuff */
+
+/*******************************************************************************
+*                     FIFO Size Configuration in Host mode
+*  
+*  (i) Receive data FIFO size = (Largest Packet Size / 4) + 1 or 
+*                             2x (Largest Packet Size / 4) + 1,  If a 
+*                             high-bandwidth channel or multiple isochronous 
+*                             channels are enabled
+*
+*  (ii) For the host nonperiodic Transmit FIFO is the largest maximum packet size 
+*      for all supported nonperiodic OUT channels. Typically, a space 
+*      corresponding to two Largest Packet Size is recommended.
+*
+*  (iii) The minimum amount of RAM required for Host periodic Transmit FIFO is 
+*        the largest maximum packet size for all supported periodic OUT channels.
+*        If there is at least one High Bandwidth Isochronous OUT endpoint, 
+*        then the space must be at least two times the maximum packet size for 
+*        that channel.
+*******************************************************************************/
+
+/****************** USB OTG HS CONFIGURATION (for host) ***********************/
+#ifdef USB_OTG_HS_CORE
+ #define RX_FIFO_HS_SIZE                          512
+ #define TXH_NP_HS_FIFOSIZ                        256
+ #define TXH_P_HS_FIFOSIZ                         256
+
+// #define USB_OTG_HS_LOW_PWR_MGMT_SUPPORT
+// #define USB_OTG_HS_SOF_OUTPUT_ENABLED
+
+// #define USB_OTG_INTERNAL_VBUS_ENABLED
+#define USB_OTG_EXTERNAL_VBUS_ENABLED
+
+ #ifdef USE_ULPI_PHY
+  #define USB_OTG_ULPI_PHY_ENABLED
+ #endif
+ #ifdef USE_EMBEDDED_PHY
+   #define USB_OTG_EMBEDDED_PHY_ENABLED
+ #endif
+ #define USB_OTG_HS_INTERNAL_DMA_ENABLED
+// #define USB_OTG_HS_DEDICATED_EP1_ENABLED
+#endif
+
+/****************** USB OTG FS CONFIGURATION (for host) ***********************/
+#ifdef USB_OTG_FS_CORE
+ //#define RX_FIFO_FS_SIZE                          128 // already defined for device (and it's the same)
+ #define TXH_NP_FS_FIFOSIZ                         96
+ #define TXH_P_FS_FIFOSIZ                          96
+
+// #define USB_OTG_FS_LOW_PWR_MGMT_SUPPORT
+// #define USB_OTG_FS_SOF_OUTPUT_ENABLED
+#endif
+
+/* END host specific stuff */
+
 /****************** USB OTG MODE CONFIGURATION ********************************/
-//#define USE_HOST_MODE
+//#define USE_HOST_MODE // set in Makefile
 #define USE_DEVICE_MODE
-//#define USE_OTG_MODE
+//#define USE_OTG_MODE // set in Makefile
 
 #ifndef USB_OTG_FS_CORE
  #ifndef USB_OTG_HS_CORE
diff --git a/stm/lib/usb_core.c b/stm/lib/usb_core.c
index 4b28c085f2..b0cce88046 100644
--- a/stm/lib/usb_core.c
+++ b/stm/lib/usb_core.c
@@ -617,7 +617,7 @@ USB_OTG_STS USB_OTG_CoreInitHost(USB_OTG_CORE_HANDLE *pdev)
   USB_OTG_HCFG_TypeDef            hcfg;
   
 #ifdef USE_OTG_MODE
-  USB_OTG_OTGCTL_TypeDef          gotgctl;
+  USB_OTG_GOTGCTL_TypeDef          gotgctl;
 #endif
   
   uint32_t                        i = 0;
diff --git a/stm/main.c b/stm/main.c
index 44db47f13b..cdc4432c09 100644
--- a/stm/main.c
+++ b/stm/main.c
@@ -307,7 +307,9 @@ char *strdup(const char *str) {
 static const char *readline_hist[READLINE_HIST_SIZE] = {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL};
 
 void stdout_tx_str(const char *str) {
-    //usart_tx_str(str); // disabled because usart is a Python object and we now need specify which USART port
+    if (pyb_usart_global_debug != PYB_USART_NONE) {
+        usart_tx_str(pyb_usart_global_debug, str);
+    }
     usb_vcp_send_str(str);
 }
 
@@ -322,10 +324,10 @@ int readline(vstr_t *line, const char *prompt) {
             if (usb_vcp_rx_any() != 0) {
                 c = usb_vcp_rx_get();
                 break;
-            } /*else if (usart_rx_any()) { // disabled because usart is a Python object and we now need specify which USART port
-                c = usart_rx_char();
+            } else if (pyb_usart_global_debug != PYB_USART_NONE && usart_rx_any(pyb_usart_global_debug)) {
+                c = usart_rx_char(pyb_usart_global_debug);
                 break;
-            }*/
+            }
             sys_tick_delay_ms(1);
             if (storage_needs_flush()) {
                 storage_flush();
@@ -775,7 +777,9 @@ int main(void) {
     switch_init();
     storage_init();
 
-    //usart_init(); disabled while wi-fi is enabled; also disabled because now usart is a proper Python object
+    // uncomment these 2 lines if you want REPL on USART_6 (or another usart) as well as on USB VCP
+    //pyb_usart_global_debug = PYB_USART_6;
+    //usart_init(pyb_usart_global_debug, 115200);
 
     int first_soft_reset = true;
 
@@ -937,6 +941,9 @@ soft_reset:
     // USB
     usb_init();
 
+    // USB host; not working!
+    //pyb_usbh_init();
+
     // MMA
     if (first_soft_reset) {
         // init and reset address to zero
diff --git a/stm/printf.c b/stm/printf.c
index fa94269257..c644cd94ff 100644
--- a/stm/printf.c
+++ b/stm/printf.c
@@ -220,14 +220,10 @@ void stdout_print_strn(void *data, const char *str, unsigned int len) {
     // send stdout to USART, USB CDC VCP, and LCD if nothing else
     bool any = false;
 
-    // TODO should have a setting for which USART port to send to
-#if 0 // if 0'd out so that we're not calling functions with the wrong arguments
-    if (usart_is_enabled()) {
-        usart_tx_strn_cooked(str, len);
+    if (pyb_usart_global_debug != PYB_USART_NONE) {
+        usart_tx_strn_cooked(pyb_usart_global_debug, str, len);
         any = true;
     }
-#endif
-
     if (usb_vcp_is_enabled()) {
         usb_vcp_send_strn_cooked(str, len);
         any = true;
diff --git a/stm/stm32fxxx_it.c b/stm/stm32fxxx_it.c
index e254ccc899..c1a9a0702f 100644
--- a/stm/stm32fxxx_it.c
+++ b/stm/stm32fxxx_it.c
@@ -31,6 +31,7 @@
 #include "stm32fxxx_it.h"
 #include "stm32f4xx_exti.h"
 #include "usb_core.h"
+//#include "usb_hcd_int.h" // for usb host mode only
 //#include "usbd_core.h"
 
 //#include "usbd_cdc_core.h"
@@ -197,7 +198,8 @@ void OTG_HS_IRQHandler(void)
 void OTG_FS_IRQHandler(void)
 #endif
 {
-  USBD_OTG_ISR_Handler (&USB_OTG_dev);
+  USBD_OTG_ISR_Handler (&USB_OTG_dev); // device mode
+  //USBH_OTG_ISR_Handler (&USB_OTG_dev); // host mode FIXME
 }
 
 #ifdef USB_OTG_HS_DEDICATED_EP1_ENABLED 
diff --git a/stm/usart.c b/stm/usart.c
index bc5bfc7369..5f47ec788a 100644
--- a/stm/usart.c
+++ b/stm/usart.c
@@ -8,20 +8,14 @@
 #include "obj.h"
 #include "usart.h"
 
-static bool is_enabled;
-
-typedef enum {
-    PYB_USART_1 = 1,
-    PYB_USART_2 = 2,
-    PYB_USART_3 = 3,
-    PYB_USART_6 = 4,
-    PYB_USART_MAX = 4,
-} pyb_usart_t;
+pyb_usart_t pyb_usart_global_debug = PYB_USART_NONE;
 
 static USART_TypeDef *usart_get_base(pyb_usart_t usart_id) {
     USART_TypeDef *USARTx=NULL;
 
     switch (usart_id) {
+        case PYB_USART_NONE:
+            break;
         case PYB_USART_1:
             USARTx = USART1;
             break;
@@ -52,6 +46,9 @@ void usart_init(pyb_usart_t usart_id, uint32_t baudrate) {
     void (*RCC_APBxPeriphClockCmd)(uint32_t, FunctionalState)=NULL;
 
     switch (usart_id) {
+        case PYB_USART_NONE:
+            return;
+
         case PYB_USART_1:
             USARTx = USART1;
 
@@ -128,16 +125,13 @@ void usart_init(pyb_usart_t usart_id, uint32_t baudrate) {
     USART_Cmd(USARTx, ENABLE);
 }
 
-bool usart_is_enabled(void) {
-    return is_enabled;
-}
-
-bool usart_rx_any(void) {
-    return USART_GetFlagStatus(USART6, USART_FLAG_RXNE) == SET;
+bool usart_rx_any(pyb_usart_t usart_id) {
+    USART_TypeDef *USARTx = usart_get_base(usart_id);
+    return USART_GetFlagStatus(USARTx, USART_FLAG_RXNE) == SET;
 }
 
 int usart_rx_char(pyb_usart_t usart_id) {
-    USART_TypeDef *USARTx= usart_get_base(usart_id);
+    USART_TypeDef *USARTx = usart_get_base(usart_id);
     return USART_ReceiveData(USARTx);
 }
 
@@ -176,8 +170,8 @@ typedef struct _pyb_usart_obj_t {
 } pyb_usart_obj_t;
 
 static mp_obj_t usart_obj_status(mp_obj_t self_in) {
-    // TODO make it check the correct USART port!
-    if (usart_rx_any()) {
+    pyb_usart_obj_t *self = self_in;
+    if (usart_rx_any(self->usart_id)) {
         return mp_const_true;
     } else {
         return mp_const_false;
diff --git a/stm/usart.h b/stm/usart.h
index 15ed419fe7..541cb757c8 100644
--- a/stm/usart.h
+++ b/stm/usart.h
@@ -1 +1,18 @@
+typedef enum {
+    PYB_USART_NONE = 0,
+    PYB_USART_1 = 1,
+    PYB_USART_2 = 2,
+    PYB_USART_3 = 3,
+    PYB_USART_6 = 4,
+    PYB_USART_MAX = 4,
+} pyb_usart_t;
+
+extern pyb_usart_t pyb_usart_global_debug;
+
+void usart_init(pyb_usart_t usart_id, uint32_t baudrate);
+bool usart_rx_any(pyb_usart_t usart_id);
+int usart_rx_char(pyb_usart_t usart_id);
+void usart_tx_str(pyb_usart_t usart_id, const char *str);
+void usart_tx_strn_cooked(pyb_usart_t usart_id, const char *str, int len);
+
 mp_obj_t pyb_Usart(mp_obj_t usart_id, mp_obj_t baudrate);
diff --git a/stm/usb.c b/stm/usb.c
index b0fbfa1941..ed2b0359b9 100644
--- a/stm/usb.c
+++ b/stm/usb.c
@@ -80,7 +80,7 @@ void usb_vcp_send_strn(const char *str, int len) {
     }
 }
 
-#include "lib/usbd_conf.h"
+#include "usbd_conf.h"
 
 /* These are external variables imported from CDC core to be used for IN 
    transfer management. */
@@ -105,3 +105,30 @@ void usb_vcp_send_strn_cooked(const char *str, int len) {
 void usb_hid_send_report(uint8_t *buf) {
     USBD_HID_SendReport(&USB_OTG_dev, buf, 4);
 }
+
+/******************************************************************************/
+// code for experimental USB OTG support
+
+#ifdef USE_HOST_MODE
+
+#include "lib-otg/usbh_core.h"
+#include "lib-otg/usbh_usr.h"
+#include "lib-otg/usbh_hid_core.h"
+
+__ALIGN_BEGIN USBH_HOST USB_Host __ALIGN_END ;
+
+static int host_is_enabled = 0;
+void pyb_usbh_init(void) {
+    if (!host_is_enabled) {
+        // only init USBH once in the device's power-lifetime
+        /* Init Host Library */
+        USBH_Init(&USB_OTG_dev, USB_OTG_FS_CORE_ID, &USB_Host, &HID_cb, &USR_Callbacks);
+    }
+    host_is_enabled = 1;
+}
+
+void pyb_usbh_process(void) {
+    USBH_Process(&USB_OTG_dev, &USB_Host);
+}
+
+#endif // USE_HOST_MODE
diff --git a/stm/usb.h b/stm/usb.h
index c4b3b151fb..db1f0a9d37 100644
--- a/stm/usb.h
+++ b/stm/usb.h
@@ -6,3 +6,6 @@ void usb_vcp_send_str(const char* str);
 void usb_vcp_send_strn(const char* str, int len);
 void usb_vcp_send_strn_cooked(const char *str, int len);
 void usb_hid_send_report(uint8_t *buf); // 4 bytes for mouse: ?, x, y, ?
+
+void pyb_usbh_init(void);
+void pyb_usbh_process(void);