diff --git a/ports/stm32f4/boards/meowbit_v121/board.c b/ports/stm32f4/boards/meowbit_v121/board.c
index 2fa3729803..a0ae988249 100644
--- a/ports/stm32f4/boards/meowbit_v121/board.c
+++ b/ports/stm32f4/boards/meowbit_v121/board.c
@@ -74,7 +74,7 @@ uint8_t display_init_sequence[] = {
 void board_init(void) {
     displayio_fourwire_obj_t* bus = &displays[0].fourwire_bus;
     bus->base.type = &displayio_fourwire_type;
-    busio_spi_obj_t *internal_spi = &spi;
+    busio_spi_obj_t *internal_spi = &supervisor_flash_spi_bus;
     common_hal_displayio_fourwire_construct(bus,
         internal_spi,
         &pin_PA08, // Command or data
diff --git a/ports/stm32f4/boards/meowbit_v121/mpconfigboard.h b/ports/stm32f4/boards/meowbit_v121/mpconfigboard.h
index b807153831..c849e03b6c 100644
--- a/ports/stm32f4/boards/meowbit_v121/mpconfigboard.h
+++ b/ports/stm32f4/boards/meowbit_v121/mpconfigboard.h
@@ -37,7 +37,7 @@
 
 #define BOARD_OSC_DIV 12
 #define BOARD_NO_VBUS_SENSE
-// #define BOARD_VTOR_DEFER //Leave VTOR relocation to bootloader
+#define BOARD_VTOR_DEFER //Leave VTOR relocation to bootloader
 #define BOARD_USE_INTERNAL_SPI
 
 // On-board flash
diff --git a/ports/stm32f4/boards/meowbit_v121/mpconfigboard.mk b/ports/stm32f4/boards/meowbit_v121/mpconfigboard.mk
index c813b4120a..340fd9d3b7 100644
--- a/ports/stm32f4/boards/meowbit_v121/mpconfigboard.mk
+++ b/ports/stm32f4/boards/meowbit_v121/mpconfigboard.mk
@@ -9,7 +9,7 @@ EXTERNAL_FLASH_DEVICE_COUNT = 1
 EXTERNAL_FLASH_DEVICES = W25Q16JV_IQ
 LONGINT_IMPL = MPZ
 
-# BOOTLOADER_OFFSET = 0x8010000
+BOOTLOADER_OFFSET = 0x8010000
 
 # INTERNAL_FLASH_FILESYSTEM = 1
 # LONGINT_IMPL = NONE
@@ -19,5 +19,5 @@ MCU_VARIANT = stm32f4
 MCU_SUB_VARIANT = stm32f401xe
 MCU_PACKAGE = 64
 CMSIS_MCU = STM32F401xE
-# LD_FILE = boards/STM32F401_boot.ld 
-LD_FILE = boards/STM32F401_fs.ld #use for internal flash
\ No newline at end of file
+LD_FILE = boards/STM32F401_boot.ld 
+# LD_FILE = boards/STM32F401_fs.ld #use for internal flash
\ No newline at end of file
diff --git a/ports/stm32f4/boards/meowbit_v121/pins.c b/ports/stm32f4/boards/meowbit_v121/pins.c
index def551c3bb..af896fad87 100644
--- a/ports/stm32f4/boards/meowbit_v121/pins.c
+++ b/ports/stm32f4/boards/meowbit_v121/pins.c
@@ -13,7 +13,7 @@ STATIC const mp_rom_map_elem_t board_module_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR_DISP_CS), MP_ROM_PTR(&pin_PB12) },
     { MP_ROM_QSTR(MP_QSTR_DISP_DC), MP_ROM_PTR(&pin_PA08) },
     { MP_ROM_QSTR(MP_QSTR_DISP_RST), MP_ROM_PTR(&pin_PB10) },
-    { MP_ROM_QSTR(MP_QSTR_DISP_BL), MP_ROM_PTR(&pin_PB03) }, //what is this, backlight?
+    { MP_ROM_QSTR(MP_QSTR_DISP_BL), MP_ROM_PTR(&pin_PB03) },
 
     { MP_ROM_QSTR(MP_QSTR_BUZZ), MP_ROM_PTR(&pin_PB08) },
     { MP_ROM_QSTR(MP_QSTR_BTNA), MP_ROM_PTR(&pin_PB09) },
@@ -62,8 +62,7 @@ STATIC const mp_rom_map_elem_t board_module_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR_P0), MP_ROM_PTR(&pin_PA00) },
     { MP_ROM_QSTR(MP_QSTR_P3), MP_ROM_PTR(&pin_PB00) },
 
-    { MP_ROM_QSTR(MP_QSTR_INTERNAL_SPI), MP_ROM_PTR(&spi) },
-
     { MP_ROM_QSTR(MP_QSTR_DISPLAY), MP_ROM_PTR(&displays[0].display)},
+    { MP_ROM_QSTR(MP_QSTR_INTERNAL_SPI), MP_ROM_PTR(&supervisor_flash_spi_bus) },
 };
 MP_DEFINE_CONST_DICT(board_module_globals, board_module_globals_table);
diff --git a/ports/stm32f4/common-hal/pulseio/PWMOut.c b/ports/stm32f4/common-hal/pulseio/PWMOut.c
index 000325be30..50bacbb514 100644
--- a/ports/stm32f4/common-hal/pulseio/PWMOut.c
+++ b/ports/stm32f4/common-hal/pulseio/PWMOut.c
@@ -68,9 +68,8 @@ STATIC uint32_t timer_get_source_freq(uint32_t tim_id) {
 }
 
 STATIC uint32_t timer_get_internal_duty(uint16_t duty, uint32_t period) {
-    //duty cycle is (0xFFFF - duty)/0xFFFF fraction x (number of pulses per period)
-    //Note that pulses are inverted, so duty cycle is inverted
-    return ((0xFFFF - duty)*period) / ((1 << 16) - 1);
+    //duty cycle is duty/0xFFFF fraction x (number of pulses per period)
+    return (duty*period) / ((1 << 16) - 1);
 }
 
 STATIC void timer_get_optimal_divisors(uint32_t*period, uint32_t*prescaler, 
@@ -114,11 +113,12 @@ pwmout_result_t common_hal_pulseio_pwmout_construct(pulseio_pwmout_obj_t* self,
     bool first_time_setup = true;
 
     for (uint i = 0; i < tim_num; i++) {
-        uint8_t l_tim_index = mcu_tim_pin_list[i].tim_index - 1;
-        uint8_t l_tim_channel = mcu_tim_pin_list[i].channel_index - 1;
+        const mcu_tim_pin_obj_t * l_tim = &mcu_tim_pin_list[i];
+        uint8_t l_tim_index = l_tim->tim_index - 1;
+        uint8_t l_tim_channel = l_tim->channel_index - 1;
 
         //if pin is same
-        if (mcu_tim_pin_list[i].pin == pin) {
+        if (l_tim->pin == pin) {
             //check if the timer has a channel active
             if (reserved_tim[l_tim_index] != 0) {
                 //is it the same channel? (or all channels reserved by a var-freq)
@@ -139,7 +139,7 @@ pwmout_result_t common_hal_pulseio_pwmout_construct(pulseio_pwmout_obj_t* self,
                 first_time_setup = false; //skip setting up the timer
             }
             //No problems taken, so set it up
-            self->tim = &mcu_tim_pin_list[i]; 
+            self->tim = l_tim; 
             break;
         }
     }
@@ -203,11 +203,8 @@ pwmout_result_t common_hal_pulseio_pwmout_construct(pulseio_pwmout_obj_t* self,
     //Channel/PWM init
     self->chan_handle.OCMode = TIM_OCMODE_PWM1;
     self->chan_handle.Pulse = timer_get_internal_duty(duty, period);
-    self->chan_handle.OCPolarity = TIM_OCPOLARITY_LOW;
+    self->chan_handle.OCPolarity = TIM_OCPOLARITY_HIGH;
     self->chan_handle.OCFastMode = TIM_OCFAST_DISABLE;
-    self->chan_handle.OCNPolarity = TIM_OCNPOLARITY_LOW; // needed for TIM1 and TIM8
-    self->chan_handle.OCIdleState = TIM_OCIDLESTATE_SET; // needed for TIM1 and TIM8
-    self->chan_handle.OCNIdleState = TIM_OCNIDLESTATE_SET; // needed for TIM1 and TIM8
     if (HAL_TIM_PWM_ConfigChannel(&self->handle, &self->chan_handle, self->channel) != HAL_OK) {
         mp_raise_ValueError(translate("Could not initialize channel"));
     }
diff --git a/shared-module/displayio/__init__.c b/shared-module/displayio/__init__.c
index 8d9f148834..efa61265e6 100644
--- a/shared-module/displayio/__init__.c
+++ b/shared-module/displayio/__init__.c
@@ -104,7 +104,7 @@ void reset_displays(void) {
                     }
                 #endif
                 #ifdef BOARD_USE_INTERNAL_SPI
-                    if (original_spi == (mp_obj_t)(&spi)) {
+                    if (original_spi == (mp_obj_t)(&supervisor_flash_spi_bus)) {
                         continue;
                     }
                 #endif
diff --git a/supervisor/shared/external_flash/spi_flash.c b/supervisor/shared/external_flash/spi_flash.c
index 12888f2d33..67e64c970e 100644
--- a/supervisor/shared/external_flash/spi_flash.c
+++ b/supervisor/shared/external_flash/spi_flash.c
@@ -36,33 +36,33 @@
 #include "py/mpconfig.h"
 
 digitalio_digitalinout_obj_t cs_pin;
-busio_spi_obj_t spi;
+busio_spi_obj_t supervisor_flash_spi_bus;
 
 const external_flash_device* flash_device;
 uint32_t spi_flash_baudrate;
 
 // Enable the flash over SPI.
 static void flash_enable(void) {
-    while (!common_hal_busio_spi_try_lock(&spi)) {}
+    while (!common_hal_busio_spi_try_lock(&supervisor_flash_spi_bus)) {}
     common_hal_digitalio_digitalinout_set_value(&cs_pin, false);
 }
 
 // Disable the flash over SPI.
 static void flash_disable(void) {
     common_hal_digitalio_digitalinout_set_value(&cs_pin, true);
-    common_hal_busio_spi_unlock(&spi);
+    common_hal_busio_spi_unlock(&supervisor_flash_spi_bus);
 }
 
 static bool transfer(uint8_t* command, uint32_t command_length, uint8_t* data_in, uint8_t* data_out, uint32_t data_length) {
     flash_enable();
-    bool status = common_hal_busio_spi_write(&spi, command, command_length);
+    bool status = common_hal_busio_spi_write(&supervisor_flash_spi_bus, command, command_length);
     if (status) {
         if (data_in != NULL && data_out != NULL) {
-            status = common_hal_busio_spi_transfer(&spi, data_out, data_in, data_length);
+            status = common_hal_busio_spi_transfer(&supervisor_flash_spi_bus, data_out, data_in, data_length);
         } else if (data_out != NULL) {
-            status = common_hal_busio_spi_read(&spi, data_out, data_length, 0xff);
+            status = common_hal_busio_spi_read(&supervisor_flash_spi_bus, data_out, data_length, 0xff);
         } else if (data_in != NULL) {
-            status = common_hal_busio_spi_write(&spi, data_in, data_length);
+            status = common_hal_busio_spi_write(&supervisor_flash_spi_bus, data_in, data_length);
         }
     }
     flash_disable();
@@ -103,10 +103,10 @@ bool spi_flash_write_data(uint32_t address, uint8_t* data, uint32_t data_length)
     // Write the SPI flash write address into the bytes following the command byte.
     address_to_bytes(address, request + 1);
     flash_enable();
-    common_hal_busio_spi_configure(&spi, spi_flash_baudrate, 0, 0, 8);
-    bool status = common_hal_busio_spi_write(&spi, request, 4);
+    common_hal_busio_spi_configure(&supervisor_flash_spi_bus, spi_flash_baudrate, 0, 0, 8);
+    bool status = common_hal_busio_spi_write(&supervisor_flash_spi_bus, request, 4);
     if (status) {
-        status = common_hal_busio_spi_write(&spi, data, data_length);
+        status = common_hal_busio_spi_write(&supervisor_flash_spi_bus, data, data_length);
     }
     flash_disable();
     return status;
@@ -122,10 +122,10 @@ bool spi_flash_read_data(uint32_t address, uint8_t* data, uint32_t data_length)
     // Write the SPI flash write address into the bytes following the command byte.
     address_to_bytes(address, request + 1);
     flash_enable();
-    common_hal_busio_spi_configure(&spi, spi_flash_baudrate, 0, 0, 8);
-    bool status = common_hal_busio_spi_write(&spi, request, command_length);
+    common_hal_busio_spi_configure(&supervisor_flash_spi_bus, spi_flash_baudrate, 0, 0, 8);
+    bool status = common_hal_busio_spi_write(&supervisor_flash_spi_bus, request, command_length);
     if (status) {
-        status = common_hal_busio_spi_read(&spi, data, data_length, 0xff);
+        status = common_hal_busio_spi_read(&supervisor_flash_spi_bus, data, data_length, 0xff);
     }
     flash_disable();
     return status;
@@ -140,9 +140,9 @@ void spi_flash_init(void) {
     common_hal_digitalio_digitalinout_switch_to_output(&cs_pin, true, DRIVE_MODE_PUSH_PULL);
     common_hal_digitalio_digitalinout_never_reset(&cs_pin);
 
-    spi.base.type = &busio_spi_type;
-    common_hal_busio_spi_construct(&spi, SPI_FLASH_SCK_PIN, SPI_FLASH_MOSI_PIN, SPI_FLASH_MISO_PIN);
-    common_hal_busio_spi_never_reset(&spi);
+    supervisor_flash_spi_bus.base.type = &busio_spi_type;
+    common_hal_busio_spi_construct(&supervisor_flash_spi_bus, SPI_FLASH_SCK_PIN, SPI_FLASH_MOSI_PIN, SPI_FLASH_MISO_PIN);
+    common_hal_busio_spi_never_reset(&supervisor_flash_spi_bus);
 }
 
 void spi_flash_init_device(const external_flash_device* device) {
diff --git a/supervisor/spi_flash_api.h b/supervisor/spi_flash_api.h
index b477308bab..f59346e25a 100644
--- a/supervisor/spi_flash_api.h
+++ b/supervisor/spi_flash_api.h
@@ -33,7 +33,7 @@
 
 #include "shared-bindings/busio/SPI.h"
 
-extern busio_spi_obj_t spi; //Used to share SPI bus on some boards
+extern busio_spi_obj_t supervisor_flash_spi_bus; //Used to share SPI bus on some boards
 
 // This API is implemented for both normal SPI peripherals and QSPI peripherals.