diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index daa9e02a8e..f8d16129b5 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -35,7 +35,7 @@ jobs:
       with:
         python-version: 3.8
     - name: Get CP deps
-      run: python tools/ci_fetch_deps.py test ${{ github.ref }}
+      run: python tools/ci_fetch_deps.py test ${{ github.sha }}
     - name: CircuitPython version
       run: |
         git describe --dirty --tags || git log --parents HEAD~4..
@@ -141,7 +141,7 @@ jobs:
       with:
         python-version: 3.8
     - name: Get CP deps
-      run: python tools/ci_fetch_deps.py mpy-cross-mac ${{ github.ref }}
+      run: python tools/ci_fetch_deps.py mpy-cross-mac ${{ github.sha }}
     - name: CircuitPython version
       run: |
         git describe --dirty --tags
@@ -197,7 +197,7 @@ jobs:
         submodules: false
         fetch-depth: 1
     - name: Get CP deps
-      run: python tools/ci_fetch_deps.py docs ${{ github.ref }}
+      run: python tools/ci_fetch_deps.py docs ${{ github.sha }}
     - name: CircuitPython version
       run: |
         git describe --dirty --tags
@@ -269,7 +269,7 @@ jobs:
         submodules: false
         fetch-depth: 1
     - name: Get CP deps
-      run: python tools/ci_fetch_deps.py ${{ matrix.board }} ${{ github.ref }}
+      run: python tools/ci_fetch_deps.py ${{ matrix.board }} ${{ github.sha }}
     - name: Install dependencies
       run: |
         sudo apt-get install -y gettext
diff --git a/.github/workflows/create_website_pr.yml b/.github/workflows/create_website_pr.yml
index ad33cca136..007cfbd402 100644
--- a/.github/workflows/create_website_pr.yml
+++ b/.github/workflows/create_website_pr.yml
@@ -25,7 +25,7 @@ jobs:
       with:
         python-version: 3.8
     - name: Get CP deps
-      run: python tools/ci_fetch_deps.py website ${{ github.ref }}
+      run: python tools/ci_fetch_deps.py website ${{ github.sha }}
     - name: Install deps
       run: |
         pip install -r requirements-dev.txt
diff --git a/.github/workflows/ports_windows.yml b/.github/workflows/ports_windows.yml
index 8491c4026d..6339746066 100644
--- a/.github/workflows/ports_windows.yml
+++ b/.github/workflows/ports_windows.yml
@@ -70,7 +70,7 @@ jobs:
         submodules: false
         fetch-depth: 1
     - name: Get CP deps
-      run: python tools/ci_fetch_deps.py windows ${{ github.ref }}
+      run: python tools/ci_fetch_deps.py windows ${{ github.sha }}
     - name: CircuitPython version
       run: |
         git describe --dirty --tags
diff --git a/devices/ble_hci/common-hal/_bleio/__init__.c b/devices/ble_hci/common-hal/_bleio/__init__.c
index 4a439e8dd2..d8a222ecfe 100644
--- a/devices/ble_hci/common-hal/_bleio/__init__.c
+++ b/devices/ble_hci/common-hal/_bleio/__init__.c
@@ -107,6 +107,6 @@ void common_hal_bleio_gc_collect(void) {
 }
 
 
-void bleio_background(void) {
+void bleio_hci_background(void) {
     bleio_adapter_background(&common_hal_bleio_adapter_obj);
 }
diff --git a/devices/ble_hci/common-hal/_bleio/__init__.h b/devices/ble_hci/common-hal/_bleio/__init__.h
index 18bf71834f..f9caf7c5b5 100644
--- a/devices/ble_hci/common-hal/_bleio/__init__.h
+++ b/devices/ble_hci/common-hal/_bleio/__init__.h
@@ -34,7 +34,7 @@
 #include "att.h"
 #include "hci.h"
 
-void bleio_background(void);
+void bleio_hci_background(void);
 void bleio_reset(void);
 
 typedef struct {
diff --git a/ports/atmel-samd/common-hal/frequencyio/FrequencyIn.c b/ports/atmel-samd/common-hal/frequencyio/FrequencyIn.c
index f973db90b0..0bc0bc214e 100644
--- a/ports/atmel-samd/common-hal/frequencyio/FrequencyIn.c
+++ b/ports/atmel-samd/common-hal/frequencyio/FrequencyIn.c
@@ -54,12 +54,33 @@
 #endif
 
 static frequencyio_frequencyin_obj_t *active_frequencyins[TC_INST_NUM];
-volatile uint8_t reference_tc = 0xff;
+volatile uint8_t reference_tc;
 #ifdef SAM_D5X_E5X
 static uint8_t dpll_gclk;
+
+#if !BOARD_HAS_CRYSTAL
+static uint8_t osculp32k_gclk;
 #endif
 
-void frequencyin_emergency_cancel_capture(uint8_t index) {
+#endif
+
+void frequencyin_reset(void) {
+    for (uint8_t i = 0; i < TC_INST_NUM; i++) {
+        active_frequencyins[i] = NULL;
+    }
+
+    reference_tc = 0xff;
+    #ifdef SAM_D5X_E5X
+    dpll_gclk = 0xff;
+
+    #if !BOARD_HAS_CRYSTAL
+    osculp32k_gclk = 0xff;
+    #endif
+
+    #endif
+}
+
+static void frequencyin_emergency_cancel_capture(uint8_t index) {
     frequencyio_frequencyin_obj_t* self = active_frequencyins[index];
 
     NVIC_DisableIRQ(self->TC_IRQ);
@@ -93,7 +114,7 @@ void frequencyin_interrupt_handler(uint8_t index) {
 
     uint64_t current_ns = common_hal_time_monotonic_ns();
 
-    for (uint8_t i = 0; i <= (TC_INST_NUM - 1); i++) {
+    for (uint8_t i = 0; i < TC_INST_NUM; i++) {
         if (active_frequencyins[i] != NULL) {
             frequencyio_frequencyin_obj_t* self = active_frequencyins[i];
             Tc* tc = tc_insts[self->tc_index];
@@ -143,7 +164,7 @@ void frequencyin_interrupt_handler(uint8_t index) {
     ref_tc->COUNT16.INTFLAG.reg |= TC_INTFLAG_OVF;
 }
 
-void frequencyin_reference_tc_init() {
+static void frequencyin_reference_tc_init(void) {
     if (reference_tc == 0xff) {
         return;
     }
@@ -154,9 +175,6 @@ void frequencyin_reference_tc_init() {
     // use the DPLL we setup so that the reference_tc and freqin_tc(s)
     // are using the same clock frequency.
     #ifdef SAM_D5X_E5X
-    if (dpll_gclk == 0xff) {
-        frequencyin_samd51_start_dpll();
-    }
     set_timer_handler(true, reference_tc, TC_HANDLER_FREQUENCYIN);
     turn_on_clocks(true, reference_tc, dpll_gclk);
     #endif
@@ -178,7 +196,7 @@ void frequencyin_reference_tc_init() {
     #endif
 }
 
-bool frequencyin_reference_tc_enabled() {
+static bool frequencyin_reference_tc_enabled(void) {
     if (reference_tc == 0xff) {
         return false;
     }
@@ -186,7 +204,7 @@ bool frequencyin_reference_tc_enabled() {
     return tc->COUNT16.CTRLA.bit.ENABLE;
 }
 
-void frequencyin_reference_tc_enable(bool enable) {
+static void frequencyin_reference_tc_enable(bool enable) {
     if (reference_tc == 0xff) {
         return;
     }
@@ -195,56 +213,69 @@ void frequencyin_reference_tc_enable(bool enable) {
 }
 
 #ifdef SAM_D5X_E5X
-void frequencyin_samd51_start_dpll() {
+static bool frequencyin_samd51_start_dpll(void) {
     if (clock_get_enabled(0, GCLK_SOURCE_DPLL1)) {
-        return;
+        return true;
     }
 
-    uint8_t free_gclk = find_free_gclk(1);
-    if (free_gclk == 0xff) {
-        dpll_gclk = 0xff;
-        return;
+    dpll_gclk = find_free_gclk(1);
+    if (dpll_gclk == 0xff) {
+        return false;
     }
 
-    GCLK->PCHCTRL[OSCCTRL_GCLK_ID_FDPLL1].reg = GCLK_PCHCTRL_CHEN | GCLK_PCHCTRL_GEN(free_gclk);
     // TC4-7 can only have a max of 100MHz source
     // DPLL1 frequency equation with [X]OSC32K as source: 98.304MHz = 32768(2999 + 1 + 0/32)
     // Will also enable the Lock Bypass due to low-frequency sources causing DPLL unlocks
     // as outlined in the Errata (1.12.1)
     OSCCTRL->Dpll[1].DPLLRATIO.reg = OSCCTRL_DPLLRATIO_LDRFRAC(0) | OSCCTRL_DPLLRATIO_LDR(2999);
-#if BOARD_HAS_CRYSTAL
-    // we can use XOSC32K directly as the source
-    OSC32KCTRL->XOSC32K.bit.EN32K = 1;
-    OSCCTRL->Dpll[1].DPLLCTRLB.reg = OSCCTRL_DPLLCTRLB_REFCLK(1) | OSCCTRL_DPLLCTRLB_LBYPASS;
-#else
-    // can't use OSCULP32K directly; need to setup a GCLK as a reference,
-    // which must be done in samd/clocks.c to avoid waiting for sync
-    return;
-    //OSC32KCTRL->OSCULP32K.bit.EN32K = 1;
-    //OSCCTRL->Dpll[1].DPLLCTRLB.reg = OSCCTRL_DPLLCTRLB_REFCLK(0);
-#endif
-    OSCCTRL->Dpll[1].DPLLCTRLA.reg = OSCCTRL_DPLLCTRLA_ENABLE;
 
+#if BOARD_HAS_CRYSTAL
+    // we can use XOSC32K directly as the source. It has already been initialized in clocks.c
+    OSCCTRL->Dpll[1].DPLLCTRLB.reg =
+        OSCCTRL_DPLLCTRLB_REFCLK(OSCCTRL_DPLLCTRLB_REFCLK_XOSC32_Val) | OSCCTRL_DPLLCTRLB_LBYPASS;
+#else
+    // We can't use OSCULP32K directly. Set up a GCLK controlled by it
+    // Then use that GCLK as the reference oscillator for the DPLL.
+    osculp32k_gclk = find_free_gclk(1);
+    if (osculp32k_gclk == 0xff) {
+        return false;
+    }
+    enable_clock_generator(osculp32k_gclk, GCLK_GENCTRL_SRC_OSCULP32K_Val, 1);
+    GCLK->PCHCTRL[OSCCTRL_GCLK_ID_FDPLL1].reg = GCLK_PCHCTRL_CHEN | GCLK_PCHCTRL_GEN(OSCCTRL_GCLK_ID_FDPLL1);
+    OSCCTRL->Dpll[1].DPLLCTRLB.reg =
+        OSCCTRL_DPLLCTRLB_REFCLK(OSCCTRL_DPLLCTRLB_REFCLK_GCLK_Val) | OSCCTRL_DPLLCTRLB_LBYPASS;
+#endif
+
+    OSCCTRL->Dpll[1].DPLLCTRLA.reg = OSCCTRL_DPLLCTRLA_ENABLE;
     while (!(OSCCTRL->Dpll[1].DPLLSTATUS.bit.LOCK || OSCCTRL->Dpll[1].DPLLSTATUS.bit.CLKRDY)) {}
-    enable_clock_generator(free_gclk, GCLK_GENCTRL_SRC_DPLL1_Val, 1);
-    dpll_gclk = free_gclk;
+
+    enable_clock_generator(dpll_gclk, GCLK_GENCTRL_SRC_DPLL1_Val, 1);
+    return true;
 }
 
-void frequencyin_samd51_stop_dpll() {
+static void frequencyin_samd51_stop_dpll(void) {
     if (!clock_get_enabled(0, GCLK_SOURCE_DPLL1)) {
         return;
     }
 
-    disable_clock_generator(dpll_gclk);
+    if (dpll_gclk != 0xff) {
+        disable_clock_generator(dpll_gclk);
+        dpll_gclk = 0xff;
+    }
+
+    #if !BOARD_HAS_CRYSTAL
+    if (osculp32k_gclk != 0xff) {
+        disable_clock_generator(osculp32k_gclk);
+        osculp32k_gclk = 0xff;
+    }
+    #endif
 
     GCLK->PCHCTRL[OSCCTRL_GCLK_ID_FDPLL1].reg = 0;
     OSCCTRL->Dpll[1].DPLLCTRLA.reg = 0;
     OSCCTRL->Dpll[1].DPLLRATIO.reg = 0;
     OSCCTRL->Dpll[1].DPLLCTRLB.reg = 0;
-
     while (OSCCTRL->Dpll[1].DPLLSYNCBUSY.bit.ENABLE) {
     }
-    dpll_gclk = 0xff;
 }
 #endif
 
@@ -421,7 +452,7 @@ void common_hal_frequencyio_frequencyin_deinit(frequencyio_frequencyin_obj_t* se
     self->pin = NO_PIN;
 
     bool check_active = false;
-    for (uint8_t i = 0; i <= (TC_INST_NUM - 1); i++) {
+    for (uint8_t i = 0; i < TC_INST_NUM; i++) {
         if (active_frequencyins[i] != NULL) {
             check_active = true;
         }
diff --git a/ports/atmel-samd/common-hal/frequencyio/FrequencyIn.h b/ports/atmel-samd/common-hal/frequencyio/FrequencyIn.h
index 53b9f2d2d1..b1d5a58bdb 100644
--- a/ports/atmel-samd/common-hal/frequencyio/FrequencyIn.h
+++ b/ports/atmel-samd/common-hal/frequencyio/FrequencyIn.h
@@ -46,14 +46,7 @@ typedef struct {
 } frequencyio_frequencyin_obj_t;
 
 void frequencyin_interrupt_handler(uint8_t index);
-void frequencyin_emergency_cancel_capture(uint8_t index);
-void frequencyin_reference_tc_init(void);
-void frequencyin_reference_tc_enable(bool enable);
-bool frequencyin_reference_tc_enabled(void);
-#ifdef SAM_D5X_E5X
-void frequencyin_samd51_start_dpll(void);
-void frequencyin_samd51_stop_dpll(void);
-#endif
+void frequencyin_reset(void);
 
 
 #endif // MICROPY_INCLUDED_ATMEL_SAMD_COMMON_HAL_FREQUENCYIO_FREQUENCYIN_H
diff --git a/ports/atmel-samd/supervisor/port.c b/ports/atmel-samd/supervisor/port.c
index ccff352443..3298e691ab 100644
--- a/ports/atmel-samd/supervisor/port.c
+++ b/ports/atmel-samd/supervisor/port.c
@@ -71,6 +71,10 @@
 #include "common-hal/busio/__init__.h"
 #endif
 
+#if CIRCUITPY_FREQUENCYIO
+#include "common-hal/frequencyio/FrequencyIn.h"
+#endif
+
 #include "common-hal/microcontroller/Pin.h"
 
 #if CIRCUITPY_PULSEIO
@@ -388,6 +392,10 @@ void reset_port(void) {
     i2sout_reset();
     #endif
 
+    #if CIRCUITPY_FREQUENCYIO
+    frequencyin_reset();
+    #endif
+
     #if CIRCUITPY_TOUCHIO && CIRCUITPY_TOUCHIO_USE_NATIVE
     touchin_reset();
     #endif
@@ -399,7 +407,7 @@ void reset_port(void) {
     #if CIRCUITPY_PWMIO
     pwmout_reset();
     #endif
-    #if CIRCUITPY_PWMIO || CIRCUITPY_AUDIOIO
+    #if CIRCUITPY_PWMIO || CIRCUITPY_AUDIOIO || CIRCUITPY_FREQUENCYIO
     reset_timers();
     #endif
 
diff --git a/ports/broadcom/qstrdefsport.h b/ports/broadcom/qstrdefsport.h
index ca01f8037c..6b44d1062b 100644
--- a/ports/broadcom/qstrdefsport.h
+++ b/ports/broadcom/qstrdefsport.h
@@ -26,6 +26,9 @@
 
 // qstrs specific to this port, only needed if they aren't auto-generated
 
+// Prevent uncrustify from modifying these lines.
+// *FORMAT-OFF*
+
 // Entries for sys.path
 Q(/sd)
 Q(/sd/lib)
diff --git a/ports/espressif/boards/adafruit_feather_esp32s2_tft/board.c b/ports/espressif/boards/adafruit_feather_esp32s2_tft/board.c
index adc4ae1b01..c6d9b581b3 100644
--- a/ports/espressif/boards/adafruit_feather_esp32s2_tft/board.c
+++ b/ports/espressif/boards/adafruit_feather_esp32s2_tft/board.c
@@ -86,7 +86,7 @@ void board_init(void) {
 
     common_hal_busio_spi_never_reset(spi);
 
-    displayio_fourwire_obj_t* bus = &displays[0].fourwire_bus;
+    displayio_fourwire_obj_t *bus = &displays[0].fourwire_bus;
     bus->base.type = &displayio_fourwire_type;
 
     common_hal_displayio_fourwire_construct(
@@ -99,7 +99,7 @@ void board_init(void) {
         0,              // polarity
         0               // phase
         );
-    displayio_display_obj_t* display = &displays[0].display;
+    displayio_display_obj_t *display = &displays[0].display;
     display->base.type = &displayio_display_type;
 
     // workaround as board_init() is called before reset_port() in main.c
diff --git a/ports/raspberrypi/common-hal/audiopwmio/PWMAudioOut.c b/ports/raspberrypi/common-hal/audiopwmio/PWMAudioOut.c
index 0654037d66..4b4c365385 100644
--- a/ports/raspberrypi/common-hal/audiopwmio/PWMAudioOut.c
+++ b/ports/raspberrypi/common-hal/audiopwmio/PWMAudioOut.c
@@ -207,7 +207,7 @@ void common_hal_audiopwmio_pwmaudioout_play(audiopwmio_pwmaudioout_obj_t *self,
     uint32_t tx_register = (uint32_t)&pwm_hw->slice[self->left_pwm.slice].cc;
     if (self->stereo) {
         // Shift the destination if we are outputting to both PWM channels.
-        tx_register += self->left_pwm.channel * sizeof(uint16_t);
+        tx_register += self->left_pwm.ab_channel * sizeof(uint16_t);
     }
 
     self->pacing_timer = pacing_timer;
diff --git a/ports/raspberrypi/common-hal/busio/I2C.c b/ports/raspberrypi/common-hal/busio/I2C.c
index 96038b4241..87c78814c2 100644
--- a/ports/raspberrypi/common-hal/busio/I2C.c
+++ b/ports/raspberrypi/common-hal/busio/I2C.c
@@ -109,8 +109,11 @@ void common_hal_busio_i2c_construct(busio_i2c_obj_t *self,
     // set up as GPIO by the bitbangio.I2C object.
     //
     // Sets pins to open drain, high, and input.
+    //
+    // Do not use the default supplied clock stretching timeout here.
+    // It is too short for some devices. Use the busio timeout instead.
     shared_module_bitbangio_i2c_construct(&self->bitbangio_i2c, scl, sda,
-        frequency, timeout);
+        frequency, BUS_TIMEOUT_US);
 
     self->baudrate = i2c_init(self->peripheral, frequency);
 
diff --git a/ports/raspberrypi/common-hal/countio/Counter.c b/ports/raspberrypi/common-hal/countio/Counter.c
index bbf71f996e..fe7dd545f8 100644
--- a/ports/raspberrypi/common-hal/countio/Counter.c
+++ b/ports/raspberrypi/common-hal/countio/Counter.c
@@ -25,8 +25,8 @@ void common_hal_countio_counter_construct(countio_counter_obj_t *self,
         mp_raise_RuntimeError(translate("PWM slice already in use"));
     }
 
-    uint8_t channel = pwm_gpio_to_channel(self->pin_a);
-    if (!pwmio_claim_slice_channels(self->slice_num)) {
+    uint8_t ab_channel = pwm_gpio_to_channel(self->pin_a);
+    if (!pwmio_claim_slice_ab_channels(self->slice_num)) {
         mp_raise_RuntimeError(translate("PWM slice channel A already in use"));
     }
 
@@ -69,7 +69,7 @@ void common_hal_countio_counter_deinit(countio_counter_obj_t *self) {
     pwm_set_enabled(self->slice_num, false);
     pwm_set_irq_enabled(self->slice_num, false);
 
-    pwmio_release_slice_channels(self->slice_num);
+    pwmio_release_slice_ab_channels(self->slice_num);
 
     reset_pin_number(self->pin_a);
 
@@ -98,13 +98,14 @@ void common_hal_countio_counter_reset(countio_counter_obj_t *self) {
 void counter_interrupt_handler(void) {
     uint32_t mask = pwm_get_irq_status_mask();
 
-    uint8_t i = 1, pos = 1;
+    uint8_t i = 1;
+    uint8_t pos = 0;
     while (!(i & mask)) {
         i = i << 1;
         ++pos;
     }
 
-    countio_counter_obj_t *self = MP_STATE_PORT(counting)[pos - 1];
+    countio_counter_obj_t *self = MP_STATE_PORT(counting)[pos];
     if (self != NULL) {
         pwm_clear_irq(self->slice_num);
         self->count += 65536;
diff --git a/ports/raspberrypi/common-hal/nvm/ByteArray.c b/ports/raspberrypi/common-hal/nvm/ByteArray.c
index 6908cbeabf..a6c8a5ad6a 100644
--- a/ports/raspberrypi/common-hal/nvm/ByteArray.c
+++ b/ports/raspberrypi/common-hal/nvm/ByteArray.c
@@ -31,6 +31,7 @@
 
 #include "py/runtime.h"
 #include "src/rp2_common/hardware_flash/include/hardware/flash.h"
+#include "shared-bindings/microcontroller/__init__.h"
 
 extern uint32_t __flash_binary_start;
 static const uint32_t flash_binary_start = (uint32_t)&__flash_binary_start;
@@ -45,13 +46,19 @@ static void write_page(uint32_t page_addr, uint32_t offset, uint32_t len, uint8_
     // Write a whole page to flash, buffering it first and then erasing and rewriting it
     // since we can only write a whole page at a time.
     if (offset == 0 && len == FLASH_PAGE_SIZE) {
+        // disable interrupts to prevent core hang on rp2040
+        common_hal_mcu_disable_interrupts();
         flash_range_program(RMV_OFFSET(page_addr), bytes, FLASH_PAGE_SIZE);
+        common_hal_mcu_enable_interrupts();
     } else {
         uint8_t buffer[FLASH_PAGE_SIZE];
         memcpy(buffer, (uint8_t *)page_addr, FLASH_PAGE_SIZE);
         memcpy(buffer + offset, bytes, len);
+        common_hal_mcu_disable_interrupts();
         flash_range_program(RMV_OFFSET(page_addr), buffer, FLASH_PAGE_SIZE);
+        common_hal_mcu_enable_interrupts();
     }
+
 }
 
 static void erase_and_write_sector(uint32_t address, uint32_t len, uint8_t *bytes) {
@@ -60,8 +67,11 @@ static void erase_and_write_sector(uint32_t address, uint32_t len, uint8_t *byte
     uint8_t buffer[FLASH_SECTOR_SIZE];
     memcpy(buffer, (uint8_t *)CIRCUITPY_INTERNAL_NVM_START_ADDR, FLASH_SECTOR_SIZE);
     memcpy(buffer + address, bytes, len);
+    // disable interrupts to prevent core hang on rp2040
+    common_hal_mcu_disable_interrupts();
     flash_range_erase(RMV_OFFSET(CIRCUITPY_INTERNAL_NVM_START_ADDR), FLASH_SECTOR_SIZE);
     flash_range_program(RMV_OFFSET(CIRCUITPY_INTERNAL_NVM_START_ADDR), buffer, FLASH_SECTOR_SIZE);
+    common_hal_mcu_enable_interrupts();
 }
 
 void common_hal_nvm_bytearray_get_bytes(const nvm_bytearray_obj_t *self,
diff --git a/ports/raspberrypi/common-hal/pwmio/PWMOut.c b/ports/raspberrypi/common-hal/pwmio/PWMOut.c
index 27e9bd4d03..3ef4fb57f3 100644
--- a/ports/raspberrypi/common-hal/pwmio/PWMOut.c
+++ b/ports/raspberrypi/common-hal/pwmio/PWMOut.c
@@ -42,7 +42,7 @@
 uint32_t target_slice_frequencies[NUM_PWM_SLICES];
 uint32_t slice_variable_frequency;
 
-#define CHANNELS_PER_SLICE 2
+#define AB_CHANNELS_PER_SLICE 2
 static uint32_t channel_use;
 static uint32_t never_reset_channel;
 
@@ -58,11 +58,11 @@ static uint32_t never_reset_channel;
 // So 65534 should be the maximum top value, and we'll set CC to be TOP+1 as appropriate.
 #define MAX_TOP 65534
 
-static uint32_t _mask(uint8_t slice, uint8_t channel) {
-    return 1 << (slice * CHANNELS_PER_SLICE + channel);
+static uint32_t _mask(uint8_t slice, uint8_t ab_channel) {
+    return 1 << (slice * AB_CHANNELS_PER_SLICE + ab_channel);
 }
 
-bool pwmio_claim_slice_channels(uint8_t slice) {
+bool pwmio_claim_slice_ab_channels(uint8_t slice) {
     uint32_t channel_use_mask_a = _mask(slice, 0);
     uint32_t channel_use_mask_b = _mask(slice, 1);
 
@@ -78,37 +78,37 @@ bool pwmio_claim_slice_channels(uint8_t slice) {
     return true;
 }
 
-void pwmio_release_slice_channels(uint8_t slice) {
+void pwmio_release_slice_ab_channels(uint8_t slice) {
     uint32_t channel_mask = _mask(slice, 0);
     channel_use &= ~channel_mask;
     channel_mask = _mask(slice, 1);
     channel_use &= ~channel_mask;
 }
 
-void pwmout_never_reset(uint8_t slice, uint8_t channel) {
-    never_reset_channel |= _mask(slice, channel);
+void pwmout_never_reset(uint8_t slice, uint8_t ab_channel) {
+    never_reset_channel |= _mask(slice, ab_channel);
 }
 
-void pwmout_reset_ok(uint8_t slice, uint8_t channel) {
-    never_reset_channel &= ~_mask(slice, channel);
+void pwmout_reset_ok(uint8_t slice, uint8_t ab_channel) {
+    never_reset_channel &= ~_mask(slice, ab_channel);
 }
 
 void common_hal_pwmio_pwmout_never_reset(pwmio_pwmout_obj_t *self) {
-    pwmout_never_reset(self->slice, self->channel);
+    pwmout_never_reset(self->slice, self->ab_channel);
 
     never_reset_pin_number(self->pin->number);
 }
 
 void common_hal_pwmio_pwmout_reset_ok(pwmio_pwmout_obj_t *self) {
-    pwmout_reset_ok(self->slice, self->channel);
+    pwmout_reset_ok(self->slice, self->ab_channel);
 }
 
 void pwmout_reset(void) {
     // Reset all slices
     for (size_t slice = 0; slice < NUM_PWM_SLICES; slice++) {
         bool reset = true;
-        for (size_t channel = 0; channel < CHANNELS_PER_SLICE; channel++) {
-            uint32_t channel_use_mask = _mask(slice, channel);
+        for (size_t ab_channel = 0; ab_channel < AB_CHANNELS_PER_SLICE; ab_channel++) {
+            uint32_t channel_use_mask = _mask(slice, ab_channel);
             if ((never_reset_channel & channel_use_mask) != 0) {
                 reset = false;
                 continue;
@@ -124,8 +124,8 @@ void pwmout_reset(void) {
     }
 }
 
-pwmout_result_t pwmout_allocate(uint8_t slice, uint8_t channel, bool variable_frequency, uint32_t frequency) {
-    uint32_t channel_use_mask = _mask(slice, channel);
+pwmout_result_t pwmout_allocate(uint8_t slice, uint8_t ab_channel, bool variable_frequency, uint32_t frequency) {
+    uint32_t channel_use_mask = _mask(slice, ab_channel);
 
     // Check the channel first.
     if ((channel_use & channel_use_mask) != 0) {
@@ -171,15 +171,15 @@ pwmout_result_t common_hal_pwmio_pwmout_construct(pwmio_pwmout_obj_t *self,
     }
 
     uint8_t slice = pwm_gpio_to_slice_num(pin->number);
-    uint8_t channel = pwm_gpio_to_channel(pin->number);
+    uint8_t ab_channel = pwm_gpio_to_channel(pin->number);
 
-    int r = pwmout_allocate(slice, channel, variable_frequency, frequency);
+    int r = pwmout_allocate(slice, ab_channel, variable_frequency, frequency);
     if (r != PWMOUT_OK) {
         return r;
     }
 
     self->slice = slice;
-    self->channel = channel;
+    self->ab_channel = ab_channel;
 
     if (target_slice_frequencies[slice] != frequency) {
         // Reset the counter and compare values.
@@ -202,11 +202,11 @@ bool common_hal_pwmio_pwmout_deinited(pwmio_pwmout_obj_t *self) {
     return self->pin == NULL;
 }
 
-void pwmout_free(uint8_t slice, uint8_t channel) {
-    uint32_t channel_mask = _mask(slice, channel);
+void pwmout_free(uint8_t slice, uint8_t ab_channel) {
+    uint32_t channel_mask = _mask(slice, ab_channel);
     channel_use &= ~channel_mask;
     never_reset_channel &= ~channel_mask;
-    uint32_t slice_mask = ((1 << CHANNELS_PER_SLICE) - 1) << (slice * CHANNELS_PER_SLICE);
+    uint32_t slice_mask = ((1 << AB_CHANNELS_PER_SLICE) - 1) << (slice * AB_CHANNELS_PER_SLICE);
     if ((channel_use & slice_mask) == 0) {
         target_slice_frequencies[slice] = 0;
         slice_variable_frequency &= ~(1 << slice);
@@ -218,7 +218,7 @@ void common_hal_pwmio_pwmout_deinit(pwmio_pwmout_obj_t *self) {
     if (common_hal_pwmio_pwmout_deinited(self)) {
         return;
     }
-    pwmout_free(self->slice, self->channel);
+    pwmout_free(self->slice, self->ab_channel);
     reset_pin_number(self->pin->number);
     self->pin = NULL;
 }
@@ -235,13 +235,13 @@ extern void common_hal_pwmio_pwmout_set_duty_cycle(pwmio_pwmout_obj_t *self, uin
         compare_count = ((uint32_t)duty * self->top + MAX_TOP / 2) / MAX_TOP;
     }
     // compare_count is the CC register value, which should be TOP+1 for 100% duty cycle.
-    pwm_set_chan_level(self->slice, self->channel, compare_count);
+    pwm_set_chan_level(self->slice, self->ab_channel, compare_count);
     // Wait for wrap so that we know our new cc value has been applied. Clear
     // the internal interrupt and then wait for it to be set. Worst case, we
     // wait a full cycle.
-    pwm_hw->intr = 1 << self->channel;
-    while ((pwm_hw->en & (1 << self->channel)) != 0 &&
-           (pwm_hw->intr & (1 << self->channel)) == 0 &&
+    pwm_hw->intr = 1 << self->slice;
+    while ((pwm_hw->en & (1 << self->slice)) != 0 &&
+           (pwm_hw->intr & (1 << self->slice)) == 0 &&
            !mp_hal_is_interrupted()) {
     }
 }
diff --git a/ports/raspberrypi/common-hal/pwmio/PWMOut.h b/ports/raspberrypi/common-hal/pwmio/PWMOut.h
index c7707762e4..0d179934d0 100644
--- a/ports/raspberrypi/common-hal/pwmio/PWMOut.h
+++ b/ports/raspberrypi/common-hal/pwmio/PWMOut.h
@@ -24,8 +24,8 @@
  * THE SOFTWARE.
  */
 
-#ifndef MICROPY_INCLUDED_ATMEL_SAMD_COMMON_HAL_PWMIO_PWMOUT_H
-#define MICROPY_INCLUDED_ATMEL_SAMD_COMMON_HAL_PWMIO_PWMOUT_H
+#ifndef MICROPY_INCLUDED_RASPBERRY_PI_COMMON_HAL_PWMIO_PWMOUT_H
+#define MICROPY_INCLUDED_RASPBERRY_PI_COMMON_HAL_PWMIO_PWMOUT_H
 
 #include "common-hal/microcontroller/Pin.h"
 
@@ -34,8 +34,8 @@
 typedef struct {
     mp_obj_base_t base;
     const mcu_pin_obj_t *pin;
-    uint8_t slice;
-    uint8_t channel;
+    uint8_t slice;        // 0-7
+    uint8_t ab_channel;   // 0-1: A or B slice channel
     bool variable_frequency;
     uint16_t duty_cycle;
     uint32_t actual_frequency;
@@ -46,13 +46,13 @@ void pwmout_reset(void);
 // Private API for AudioPWMOut.
 void pwmio_pwmout_set_top(pwmio_pwmout_obj_t *self, uint16_t top);
 // Private APIs for RGBMatrix
-enum pwmout_result_t pwmout_allocate(uint8_t slice, uint8_t channel, bool variable_frequency, uint32_t frequency);
-void pwmout_free(uint8_t slice, uint8_t channel);
-void pwmout_never_reset(uint8_t slice, uint8_t channel);
-void pwmout_reset_ok(uint8_t slice, uint8_t channel);
+enum pwmout_result_t pwmout_allocate(uint8_t slice, uint8_t ab_channel, bool variable_frequency, uint32_t frequency);
+void pwmout_free(uint8_t slice, uint8_t ab_channel);
+void pwmout_never_reset(uint8_t slice, uint8_t ab_channel);
+void pwmout_reset_ok(uint8_t slice, uint8_t ab_channel);
 
-// Private API for countio to claim both channels on a slice
-bool pwmio_claim_slice_channels(uint8_t slice);
-void pwmio_release_slice_channels(uint8_t slice);
+// Private API for countio to claim both ab_channels on a slice
+bool pwmio_claim_slice_ab_channels(uint8_t slice);
+void pwmio_release_slice_ab_channels(uint8_t slice);
 
-#endif // MICROPY_INCLUDED_ATMEL_SAMD_COMMON_HAL_PWMIO_PWMOUT_H
+#endif // MICROPY_INCLUDED_RASPBERRY_PI_COMMON_HAL_PWMIO_PWMOUT_H
diff --git a/ports/stm/boards/espruino_pico/mpconfigboard.mk b/ports/stm/boards/espruino_pico/mpconfigboard.mk
index a078b4841a..6e4da86dd7 100644
--- a/ports/stm/boards/espruino_pico/mpconfigboard.mk
+++ b/ports/stm/boards/espruino_pico/mpconfigboard.mk
@@ -20,6 +20,7 @@ LD_FILE = boards/STM32F401xd_fs.ld
 CIRCUITPY_AESIO = 0
 CIRCUITPY_AUDIOCORE = 0
 CIRCUITPY_AUDIOPWMIO = 0
+CIRCUITPY_BLEIO_HCI = 0
 CIRCUITPY_BUSDEVICE = 0
 CIRCUITPY_BITMAPTOOLS = 0
 CIRCUITPY_FRAMEBUFFERIO = 0
diff --git a/ports/stm/boards/pyb_nano_v2/mpconfigboard.mk b/ports/stm/boards/pyb_nano_v2/mpconfigboard.mk
index 29bfd62620..3ba45e0c5b 100644
--- a/ports/stm/boards/pyb_nano_v2/mpconfigboard.mk
+++ b/ports/stm/boards/pyb_nano_v2/mpconfigboard.mk
@@ -17,6 +17,7 @@ LD_FILE = boards/STM32F411_fs.ld
 CIRCUITPY_AUDIOCORE = 0
 CIRCUITPY_AUDIOPWMIO = 0
 CIRCUITPY_BITMAPTOOLS = 0
+CIRCUITPY_BLEIO_HCI = 0
 CIRCUITPY_BUSDEVICE = 0
 CIRCUITPY_GIFIO = 0
 CIRCUITPY_KEYPAD = 0
diff --git a/ports/stm/boards/stm32f411ve_discovery/mpconfigboard.mk b/ports/stm/boards/stm32f411ve_discovery/mpconfigboard.mk
index 61e372b2c3..0929841ea5 100644
--- a/ports/stm/boards/stm32f411ve_discovery/mpconfigboard.mk
+++ b/ports/stm/boards/stm32f411ve_discovery/mpconfigboard.mk
@@ -15,8 +15,7 @@ LD_FILE = boards/STM32F411_fs.ld
 # Too big for the flash
 CIRCUITPY_AUDIOCORE = 0
 CIRCUITPY_AUDIOPWMIO = 0
-CIRCUITPY_KEYPAD = 0
-CIRCUITPY_MIDI = 0
-CIRCUITPY_MSGPACK = 0
 CIRCUITPY_BITMAPTOOLS = 0
+CIRCUITPY_BLEIO_HCI = 0
+CIRCUITPY_MSGPACK = 0
 CIRCUITPY_VECTORIO = 0
diff --git a/supervisor/shared/tick.c b/supervisor/shared/tick.c
index 40c1ef11e3..94b9d4d15e 100644
--- a/supervisor/shared/tick.c
+++ b/supervisor/shared/tick.c
@@ -37,6 +37,10 @@
 #include "supervisor/shared/autoreload.h"
 #include "supervisor/shared/stack.h"
 
+#if CIRCUITPY_BLEIO_HCI
+#include "common-hal/_bleio/__init__.h"
+#endif
+
 #if CIRCUITPY_DISPLAYIO
 #include "shared-module/displayio/__init__.h"
 #endif
@@ -69,6 +73,10 @@ static void supervisor_background_tasks(void *unused) {
 
     assert_heap_ok();
 
+    #if CIRCUITPY_BLEIO_HCI
+    bleio_hci_background();
+    #endif
+
     #if CIRCUITPY_DISPLAYIO
     displayio_background();
     #endif