diff --git a/docs/psoc6/quickref.rst b/docs/psoc6/quickref.rst
index 7a81c18f63323..efe397d597fee 100644
--- a/docs/psoc6/quickref.rst
+++ b/docs/psoc6/quickref.rst
@@ -426,6 +426,7 @@ Methods
 ^^^^^^^
 All the methods(functions) given in :ref:`machine.SPI <machine.SPI>` class have been implemented in this port
 
+
 ADC (analog to digital conversion)
 ----------------------------------
 
diff --git a/ports/esp32/boards/GENERIC_OTA/sdkconfig.board b/ports/esp32/boards/GENERIC_OTA/sdkconfig.board
index d314860cc9378..7ff939aa991f2 100644
--- a/ports/esp32/boards/GENERIC_OTA/sdkconfig.board
+++ b/ports/esp32/boards/GENERIC_OTA/sdkconfig.board
@@ -1,3 +1,6 @@
 CONFIG_BOOTLOADER_APP_ROLLBACK_ENABLE=y
 CONFIG_PARTITION_TABLE_CUSTOM=y
 CONFIG_PARTITION_TABLE_CUSTOM_FILENAME="partitions-ota.csv"
+
+# Reduce firmware size to fit in the OTA partition.
+CONFIG_COMPILER_OPTIMIZATION_CHECKS_SILENT=y
diff --git a/ports/esp32/main_esp32/idf_component.yml b/ports/esp32/main_esp32/idf_component.yml
new file mode 100644
index 0000000000000..8be21ed2fbe87
--- /dev/null
+++ b/ports/esp32/main_esp32/idf_component.yml
@@ -0,0 +1,5 @@
+## IDF Component Manager Manifest File
+dependencies:
+  espressif/mdns: "~1.1.0"
+  idf:
+    version: ">=5.0.2"
diff --git a/ports/esp32/main_esp32c3/idf_component.yml b/ports/esp32/main_esp32c3/idf_component.yml
new file mode 100644
index 0000000000000..8be21ed2fbe87
--- /dev/null
+++ b/ports/esp32/main_esp32c3/idf_component.yml
@@ -0,0 +1,5 @@
+## IDF Component Manager Manifest File
+dependencies:
+  espressif/mdns: "~1.1.0"
+  idf:
+    version: ">=5.0.2"
diff --git a/ports/esp32/main_esp32s2/idf_component.yml b/ports/esp32/main_esp32s2/idf_component.yml
index fe3213bd26af2..69e27bf8b54bc 100644
--- a/ports/esp32/main_esp32s2/idf_component.yml
+++ b/ports/esp32/main_esp32s2/idf_component.yml
@@ -1,5 +1,6 @@
 ## IDF Component Manager Manifest File
 dependencies:
+  espressif/mdns: "~1.1.0"
+  espressif/esp_tinyusb: "~1.0.0"
   idf:
     version: ">=5.0.2"
-  espressif/esp_tinyusb: "~1.0.0"
diff --git a/ports/esp32/main_esp32s3/idf_component.yml b/ports/esp32/main_esp32s3/idf_component.yml
index fe3213bd26af2..69e27bf8b54bc 100644
--- a/ports/esp32/main_esp32s3/idf_component.yml
+++ b/ports/esp32/main_esp32s3/idf_component.yml
@@ -1,5 +1,6 @@
 ## IDF Component Manager Manifest File
 dependencies:
+  espressif/mdns: "~1.1.0"
+  espressif/esp_tinyusb: "~1.0.0"
   idf:
     version: ">=5.0.2"
-  espressif/esp_tinyusb: "~1.0.0"
diff --git a/ports/esp32/modsocket.c b/ports/esp32/modsocket.c
index 7484fce786c74..ba1fe096f6946 100644
--- a/ports/esp32/modsocket.c
+++ b/ports/esp32/modsocket.c
@@ -58,6 +58,10 @@
 #define MDNS_QUERY_TIMEOUT_MS (5000)
 #define MDNS_LOCAL_SUFFIX ".local"
 
+#ifndef NO_QSTR
+#include "mdns.h"
+#endif
+
 enum {
     SOCKET_STATE_NEW,
     SOCKET_STATE_CONNECTED,
diff --git a/ports/esp32/mpconfigport.h b/ports/esp32/mpconfigport.h
index b18681bb572df..e97980c36f467 100644
--- a/ports/esp32/mpconfigport.h
+++ b/ports/esp32/mpconfigport.h
@@ -221,11 +221,11 @@ typedef long mp_off_t;
 #endif
 
 #ifndef MICROPY_HW_ENABLE_MDNS_QUERIES
-#define MICROPY_HW_ENABLE_MDNS_QUERIES      (0)
+#define MICROPY_HW_ENABLE_MDNS_QUERIES      (1)
 #endif
 
 #ifndef MICROPY_HW_ENABLE_MDNS_RESPONDER
-#define MICROPY_HW_ENABLE_MDNS_RESPONDER    (0)
+#define MICROPY_HW_ENABLE_MDNS_RESPONDER    (1)
 #endif
 
 #ifndef MICROPY_BOARD_STARTUP
diff --git a/ports/esp32/network_wlan.c b/ports/esp32/network_wlan.c
index cfedd898cdf24..3c88f8db8682a 100644
--- a/ports/esp32/network_wlan.c
+++ b/ports/esp32/network_wlan.c
@@ -42,6 +42,10 @@
 #include "esp_wifi.h"
 #include "esp_log.h"
 
+#ifndef NO_QSTR
+#include "mdns.h"
+#endif
+
 #if MICROPY_PY_NETWORK_WLAN
 
 #if (WIFI_MODE_STA & WIFI_MODE_AP != WIFI_MODE_NULL || WIFI_MODE_STA | WIFI_MODE_AP != WIFI_MODE_APSTA)
diff --git a/ports/psoc6/modules/machine/modmachine.h b/ports/psoc6/modules/machine/modmachine.h
index 9794fd9892b5a..5d1f9980cc647 100644
--- a/ports/psoc6/modules/machine/modmachine.h
+++ b/ports/psoc6/modules/machine/modmachine.h
@@ -14,7 +14,6 @@ extern const mp_obj_type_t machine_spi_type;
 extern const mp_obj_type_t machine_adc_type;
 extern const mp_obj_type_t machine_adcblock_type;
 
-
 /* Note: the static functions' prototypes in the .c file cannot be declared here
 since they are static. The static type in those functions come from MPY hence
 should stay that way.  */
diff --git a/ports/stm32/Makefile b/ports/stm32/Makefile
index d5030b7e46da2..81a48249e89d3 100644
--- a/ports/stm32/Makefile
+++ b/ports/stm32/Makefile
@@ -404,7 +404,7 @@ HAL_SRC_C += $(addprefix $(STM32LIB_HAL_BASE)/Src/stm32$(MCU_SERIES)xx_,\
 	ll_utils.c \
 	)
 
-ifeq ($(MCU_SERIES),$(filter $(MCU_SERIES),f4 f7 g0 g4 h5 h7 l0 l4 wb))
+ifeq ($(MCU_SERIES),$(filter $(MCU_SERIES),f4 f7 g0 g4 h5 h7 l0 l1 l4 wb))
 HAL_SRC_C += $(addprefix $(STM32LIB_HAL_BASE)/Src/stm32$(MCU_SERIES)xx_,\
 	hal_pcd.c \
 	hal_pcd_ex.c \
diff --git a/ports/stm32/boards/NUCLEO_L152RE/mpconfigboard.h b/ports/stm32/boards/NUCLEO_L152RE/mpconfigboard.h
index 3609955893fe1..5b83a980ce164 100644
--- a/ports/stm32/boards/NUCLEO_L152RE/mpconfigboard.h
+++ b/ports/stm32/boards/NUCLEO_L152RE/mpconfigboard.h
@@ -7,6 +7,7 @@
 #define MICROPY_HW_RTC_USE_LSE      (1)
 #define MICROPY_HW_ENABLE_SERVO     (1)
 #define MICROPY_HW_ENABLE_DAC       (1)
+#define MICROPY_HW_ENABLE_USB       (0)
 
 // HSE is 8MHz, HSI is 16MHz CPU freq set to 32MHz
 // Default source for the clock is HSI.
@@ -72,3 +73,11 @@
 #define MICROPY_HW_LED_OFF(pin)     (mp_hal_pin_low(pin))
 
 #define MICROPY_HW_FLASH_LATENCY FLASH_LATENCY_1
+
+// USB config
+#if MICROPY_HW_ENABLE_USB
+#if MICROPY_HW_CLK_USE_HSI
+#error STM32L152RE cannot use USB feature with HSI clock. Use HSE.
+#endif
+#define MICROPY_HW_USB_FS (1)
+#endif
diff --git a/ports/stm32/boards/stm32l1xx_hal_conf_base.h b/ports/stm32/boards/stm32l1xx_hal_conf_base.h
index b839fd29f0a3d..5871e8a45a6f2 100644
--- a/ports/stm32/boards/stm32l1xx_hal_conf_base.h
+++ b/ports/stm32/boards/stm32l1xx_hal_conf_base.h
@@ -26,6 +26,9 @@
 #ifndef MICROPY_INCLUDED_STM32L1XX_HAL_CONF_BASE_H
 #define MICROPY_INCLUDED_STM32L1XX_HAL_CONF_BASE_H
 
+// Needs to be defined before ll_usb.h is included
+#define HAL_PCD_MODULE_ENABLED
+
 // Include various HAL modules for convenience
 #include "stm32l1xx_hal_rcc.h"
 #include "stm32l1xx_hal_gpio.h"
@@ -38,6 +41,7 @@
 #include "stm32l1xx_hal_flash.h"
 #include "stm32l1xx_hal_i2c.h"
 #include "stm32l1xx_hal_iwdg.h"
+#include "stm32l1xx_hal_pcd.h"
 #include "stm32l1xx_hal_pwr.h"
 #include "stm32l1xx_hal_rtc.h"
 #include "stm32l1xx_hal_spi.h"
@@ -50,6 +54,7 @@
 #include "stm32l1xx_ll_pwr.h"
 #include "stm32l1xx_ll_rtc.h"
 #include "stm32l1xx_ll_usart.h"
+#include "stm32l1xx_ll_usb.h"
 
 // Enable various HAL modules
 #define HAL_MODULE_ENABLED
diff --git a/ports/stm32/modmachine.c b/ports/stm32/modmachine.c
index 1869b984dab0a..69fe8f4f54a83 100644
--- a/ports/stm32/modmachine.c
+++ b/ports/stm32/modmachine.c
@@ -387,7 +387,7 @@ MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(machine_deepsleep_obj, 0, 1, machine_deepsle
 STATIC mp_obj_t machine_reset_cause(void) {
     return MP_OBJ_NEW_SMALL_INT(reset_cause);
 }
-STATIC MP_DEFINE_CONST_FUN_OBJ_0(machine_reset_cause_obj, machine_reset_cause);
+MP_DEFINE_CONST_FUN_OBJ_0(machine_reset_cause_obj, machine_reset_cause);
 
 #if MICROPY_PY_MACHINE
 
diff --git a/ports/stm32/modmachine.h b/ports/stm32/modmachine.h
index 0c776280b416c..28d9c699d63fc 100644
--- a/ports/stm32/modmachine.h
+++ b/ports/stm32/modmachine.h
@@ -29,7 +29,6 @@
 #include "py/obj.h"
 
 extern const mp_obj_type_t machine_adc_type;
-extern const mp_obj_type_t machine_timer_type;
 extern const mp_obj_type_t machine_i2c_type;
 extern const mp_obj_type_t machine_i2s_type;
 extern const mp_obj_type_t machine_spi_type;
@@ -49,6 +48,7 @@ MP_DECLARE_CONST_FUN_OBJ_VAR_BETWEEN(machine_freq_obj);
 MP_DECLARE_CONST_FUN_OBJ_0(machine_idle_obj);
 MP_DECLARE_CONST_FUN_OBJ_VAR_BETWEEN(machine_lightsleep_obj);
 MP_DECLARE_CONST_FUN_OBJ_VAR_BETWEEN(machine_deepsleep_obj);
+MP_DECLARE_CONST_FUN_OBJ_0(machine_reset_cause_obj);
 
 MP_DECLARE_CONST_FUN_OBJ_0(machine_disable_irq_obj);
 MP_DECLARE_CONST_FUN_OBJ_VAR_BETWEEN(machine_enable_irq_obj);
diff --git a/ports/stm32/mpconfigboard_common.h b/ports/stm32/mpconfigboard_common.h
index 8f2a6e530a540..149d2ae73a636 100644
--- a/ports/stm32/mpconfigboard_common.h
+++ b/ports/stm32/mpconfigboard_common.h
@@ -586,7 +586,7 @@
 // Whether the USB peripheral is device-only, or multiple OTG
 // For STM32G0 and STM32H5 the USB peripheral supports device and host mode,
 // but otherwise acts like a non-multi-OTG peripheral.
-#if defined(STM32G0) || defined(STM32G4) || defined(STM32H5) || defined(STM32L0) || defined(STM32L432xx) || defined(STM32WB)
+#if defined(STM32G0) || defined(STM32G4) || defined(STM32H5) || defined(STM32L0) || defined(STM32L1) || defined(STM32L432xx) || defined(STM32WB)
 #define MICROPY_HW_USB_IS_MULTI_OTG (0)
 #else
 #define MICROPY_HW_USB_IS_MULTI_OTG (1)
diff --git a/ports/stm32/powerctrlboot.c b/ports/stm32/powerctrlboot.c
index 149c34ae63ec4..51b740a809031 100644
--- a/ports/stm32/powerctrlboot.c
+++ b/ports/stm32/powerctrlboot.c
@@ -389,22 +389,7 @@ void SystemClock_Config(void) {
     powerctrl_config_systick();
 
     #if MICROPY_HW_ENABLE_USB
-    // Enable the 48MHz internal oscillator
-    RCC->CRRCR |= RCC_CRRCR_HSI48ON;
     RCC->APB2ENR |= RCC_APB2ENR_SYSCFGEN;
-    SYSCFG->CFGR3 |= SYSCFG_CFGR3_ENREF_HSI48;
-    while (!(RCC->CRRCR & RCC_CRRCR_HSI48RDY)) {
-        // Wait for HSI48 to be ready
-    }
-
-    // Select RC48 as HSI48 for USB and RNG
-    RCC->CCIPR |= RCC_CCIPR_HSI48SEL;
-
-    // Synchronise HSI48 with 1kHz USB SoF
-    __HAL_RCC_CRS_CLK_ENABLE();
-    CRS->CR = 0x20 << CRS_CR_TRIM_Pos;
-    CRS->CFGR = 2 << CRS_CFGR_SYNCSRC_Pos | 0x22 << CRS_CFGR_FELIM_Pos
-        | __HAL_RCC_CRS_RELOADVALUE_CALCULATE(48000000, 1000) << CRS_CFGR_RELOAD_Pos;
     #endif
 
     // Disable the Debug Module in low-power mode due to prevent
diff --git a/ports/stm32/stm32_it.c b/ports/stm32/stm32_it.c
index 84c05602b57b7..483537b649379 100644
--- a/ports/stm32/stm32_it.c
+++ b/ports/stm32/stm32_it.c
@@ -320,7 +320,7 @@ void USB_IRQHandler(void) {
 }
 #endif
 
-#elif defined(STM32G4) || defined(STM32WB)
+#elif defined(STM32G4) || defined(STM32L1) || defined(STM32WB)
 
 #if MICROPY_HW_USB_FS
 void USB_LP_IRQHandler(void) {
diff --git a/ports/stm32/usb.c b/ports/stm32/usb.c
index 94d62f7625a57..c3b8544417d0b 100644
--- a/ports/stm32/usb.c
+++ b/ports/stm32/usb.c
@@ -59,7 +59,7 @@
 #endif
 
 // Maximum number of endpoints (excluding EP0)
-#if defined(STM32G0) || defined(STM32G4) || defined(STM32H5) || defined(STM32L0) || defined(STM32WB)
+#if defined(STM32G0) || defined(STM32G4) || defined(STM32H5) || defined(STM32L0) || defined(STM32L1) || defined(STM32WB)
 #define MAX_ENDPOINT(dev_id) (7)
 #elif defined(STM32L4)
 #define MAX_ENDPOINT(dev_id) (5)
diff --git a/ports/stm32/usbd_conf.c b/ports/stm32/usbd_conf.c
index 9f187fc08b57a..5d9e7177de564 100644
--- a/ports/stm32/usbd_conf.c
+++ b/ports/stm32/usbd_conf.c
@@ -75,6 +75,16 @@ void HAL_PCD_MspInit(PCD_HandleTypeDef *hpcd) {
         mp_hal_pin_config(pin_A12, MP_HAL_PIN_MODE_ANALOG, MP_HAL_PIN_PULL_NONE, 0);
         mp_hal_pin_config_speed(pin_A12, GPIO_SPEED_FREQ_VERY_HIGH);
 
+        #elif defined(STM32L1)
+
+        // STM32L1 doesn't have an alternate function for USB.
+        // To be disconnected from all peripherals, put in input mode.
+
+        mp_hal_pin_config(pin_A11, MP_HAL_PIN_MODE_INPUT, MP_HAL_PIN_PULL_NONE, 0);
+        mp_hal_pin_config_speed(pin_A11, GPIO_SPEED_FREQ_VERY_HIGH);
+        mp_hal_pin_config(pin_A12, MP_HAL_PIN_MODE_INPUT, MP_HAL_PIN_PULL_NONE, 0);
+        mp_hal_pin_config_speed(pin_A12, GPIO_SPEED_FREQ_VERY_HIGH);
+
         #else
 
         // Other MCUs have an alternate function for GPIO's to be in USB mode.
@@ -149,7 +159,7 @@ void HAL_PCD_MspInit(PCD_HandleTypeDef *hpcd) {
         #elif defined(STM32L432xx)
         NVIC_SetPriority(USB_FS_IRQn, IRQ_PRI_OTG_FS);
         HAL_NVIC_EnableIRQ(USB_FS_IRQn);
-        #elif defined(STM32G4) || defined(STM32WB)
+        #elif defined(STM32G4) || defined(STM32L1) || defined(STM32WB)
         NVIC_SetPriority(USB_LP_IRQn, IRQ_PRI_OTG_FS);
         HAL_NVIC_EnableIRQ(USB_LP_IRQn);
         #else
@@ -708,6 +718,24 @@ void USBD_LL_Delay(uint32_t Delay) {
     HAL_Delay(Delay);
 }
 
+#if defined(STM32L1)
+/**
+  * @brief Software Device Connection
+  * @param hpcd: PCD handle
+  * @param state: Connection state (0: disconnected / 1: connected)
+  * @retval None
+  */
+void HAL_PCDEx_SetConnectionState(PCD_HandleTypeDef *hpcd, uint8_t state) {
+    if (state == 1) {
+        /*  DP Pull-Down is Internal */
+        __HAL_SYSCFG_USBPULLUP_ENABLE();
+    } else {
+        /*  DP Pull-Down is Internal */
+        __HAL_SYSCFG_USBPULLUP_DISABLE();
+    }
+}
+#endif
+
 #endif // MICROPY_HW_USB_FS || MICROPY_HW_USB_HS
 
 /************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/