diff --git a/lib/mp-readline/readline.c b/lib/mp-readline/readline.c
index 464916ca4e..6da71c40f5 100644
--- a/lib/mp-readline/readline.c
+++ b/lib/mp-readline/readline.c
@@ -144,7 +144,7 @@ int readline_process_char(int c) {
             goto right_arrow_key;
         } else if (c == CHAR_CTRL_K) {
             // CTRL-K is kill from cursor to end-of-line, inclusive
-            vstr_cut_tail_bytes(rl.line, last_line_len - rl.cursor_pos);
+            vstr_cut_tail_bytes(rl.line, rl.line->len - rl.cursor_pos);
             // set redraw parameters
             redraw_from_cursor = true;
         } else if (c == CHAR_CTRL_N) {
@@ -155,6 +155,7 @@ int readline_process_char(int c) {
             goto up_arrow_key;
         } else if (c == CHAR_CTRL_U) {
             // CTRL-U is kill from beginning-of-line up to cursor
+            cont_chars = count_cont_bytes(rl.line->buf+rl.orig_line_len, rl.line->buf+rl.cursor_pos);
             vstr_cut_out_bytes(rl.line, rl.orig_line_len, rl.cursor_pos - rl.orig_line_len);
             // set redraw parameters
             redraw_step_back = rl.cursor_pos - rl.orig_line_len;
@@ -342,6 +343,7 @@ left_arrow_key:
         if (c == '~') {
             if (rl.escape_seq_buf[0] == '1' || rl.escape_seq_buf[0] == '7') {
 home_key:
+                cont_chars = count_cont_bytes(rl.line->buf+rl.orig_line_len, rl.line->buf+rl.cursor_pos);
                 redraw_step_back = rl.cursor_pos - rl.orig_line_len;
             } else if (rl.escape_seq_buf[0] == '4' || rl.escape_seq_buf[0] == '8') {
 end_key:
@@ -352,7 +354,12 @@ end_key:
 delete_key:
 #endif
                 if (rl.cursor_pos < rl.line->len) {
-                    vstr_cut_out_bytes(rl.line, rl.cursor_pos, 1);
+                    size_t len = 1;
+                    while (UTF8_IS_CONT(rl.line->buf[rl.cursor_pos+len]) &&
+                            rl.cursor_pos+len < rl.line->len) {
+                        len++;
+                    }
+                    vstr_cut_out_bytes(rl.line, rl.cursor_pos, len);
                     redraw_from_cursor = true;
                 }
             } else {
diff --git a/locale/circuitpython.pot b/locale/circuitpython.pot
index ffb2e91ef6..1e227dcbc0 100644
--- a/locale/circuitpython.pot
+++ b/locale/circuitpython.pot
@@ -8,7 +8,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: PACKAGE VERSION\n"
 "Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2020-08-14 09:36-0400\n"
+"POT-Creation-Date: 2020-08-18 11:19-0400\n"
 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language-Team: LANGUAGE <LL@li.org>\n"
@@ -744,7 +744,7 @@ msgstr ""
 
 #: shared-bindings/aesio/aes.c shared-bindings/busio/SPI.c
 #: shared-bindings/microcontroller/Pin.c
-#: shared-bindings/neopixel_write/__init__.c shared-bindings/pulseio/PulseOut.c
+#: shared-bindings/neopixel_write/__init__.c
 #: shared-bindings/terminalio/Terminal.c
 msgid "Expected a %q"
 msgstr ""
@@ -1328,6 +1328,15 @@ msgstr ""
 msgid "Polygon needs at least 3 points"
 msgstr ""
 
+#: ports/atmel-samd/common-hal/pulseio/PulseOut.c
+#: ports/cxd56/common-hal/pulseio/PulseOut.c
+#: ports/nrf/common-hal/pulseio/PulseOut.c
+#: ports/stm/common-hal/pulseio/PulseOut.c
+msgid ""
+"Port does not accept pins or frequency.                                     "
+"Construct and pass a PWMOut Carrier instead"
+msgstr ""
+
 #: shared-bindings/_bleio/Adapter.c
 msgid "Prefix buffer must be on the heap"
 msgstr ""
@@ -1340,6 +1349,10 @@ msgstr ""
 msgid "Pull not used when direction is output."
 msgstr ""
 
+#: ports/stm/ref/pulseout-pre-timeralloc.c
+msgid "PulseOut not supported on this chip"
+msgstr ""
+
 #: ports/stm/common-hal/os/__init__.c
 msgid "RNG DeInit Error"
 msgstr ""
diff --git a/ports/atmel-samd/Makefile b/ports/atmel-samd/Makefile
index 1309c4e712..224168c234 100644
--- a/ports/atmel-samd/Makefile
+++ b/ports/atmel-samd/Makefile
@@ -103,7 +103,7 @@ ifeq ($(CHIP_FAMILY), same54)
 PERIPHERALS_CHIP_FAMILY=sam_d5x_e5x
 OPTIMIZATION_FLAGS ?= -O2
 # TinyUSB defines
-CFLAGS += -DCFG_TUSB_MCU=OPT_MCU_SAMD51 -DCFG_TUD_MIDI_RX_BUFSIZE=128 -DCFG_TUD_CDC_RX_BUFSIZE=256 -DCFG_TUD_MIDI_TX_BUFSIZE=128 -DCFG_TUD_CDC_TX_BUFSIZE=256 -DCFG_TUD_MSC_BUFSIZE=1024
+CFLAGS += -DCFG_TUSB_MCU=OPT_MCU_SAME5X -DCFG_TUD_MIDI_RX_BUFSIZE=128 -DCFG_TUD_CDC_RX_BUFSIZE=256 -DCFG_TUD_MIDI_TX_BUFSIZE=128 -DCFG_TUD_CDC_TX_BUFSIZE=256 -DCFG_TUD_MSC_BUFSIZE=1024
 endif
 
 # option to override default optimization level, set in boards/$(BOARD)/mpconfigboard.mk
diff --git a/ports/atmel-samd/boards/mini_sam_m4/mpconfigboard.mk b/ports/atmel-samd/boards/mini_sam_m4/mpconfigboard.mk
index ae2a1e9733..393adf8397 100644
--- a/ports/atmel-samd/boards/mini_sam_m4/mpconfigboard.mk
+++ b/ports/atmel-samd/boards/mini_sam_m4/mpconfigboard.mk
@@ -7,8 +7,8 @@ CHIP_VARIANT = SAMD51G19A
 CHIP_FAMILY = samd51
 
 QSPI_FLASH_FILESYSTEM = 1
-EXTERNAL_FLASH_DEVICE_COUNT = 1
-EXTERNAL_FLASH_DEVICES = "W25Q16JV_IM"
+EXTERNAL_FLASH_DEVICE_COUNT = 2
+EXTERNAL_FLASH_DEVICES = "W25Q16JV_IM, W25Q16JV_IQ"
 LONGINT_IMPL = MPZ
 
 # No I2S on SAMD51G
diff --git a/ports/atmel-samd/common-hal/pulseio/PulseOut.c b/ports/atmel-samd/common-hal/pulseio/PulseOut.c
index e9b2137cb0..b53c8da2ba 100644
--- a/ports/atmel-samd/common-hal/pulseio/PulseOut.c
+++ b/ports/atmel-samd/common-hal/pulseio/PulseOut.c
@@ -96,7 +96,15 @@ void pulseout_reset() {
 }
 
 void common_hal_pulseio_pulseout_construct(pulseio_pulseout_obj_t* self,
-                                            const pulseio_pwmout_obj_t* carrier) {
+                                            const pulseio_pwmout_obj_t* carrier,
+                                            const mcu_pin_obj_t* pin,
+                                            uint32_t frequency,
+                                            uint16_t duty_cycle) {
+    if (!carrier || pin || frequency) {
+        mp_raise_NotImplementedError(translate("Port does not accept pins or frequency. \
+                                    Construct and pass a PWMOut Carrier instead"));
+    }
+
     if (refcount == 0) {
         // Find a spare timer.
         Tc *tc = NULL;
diff --git a/ports/atmel-samd/mpconfigport.mk b/ports/atmel-samd/mpconfigport.mk
index 3fecf867e0..a16daf4b00 100644
--- a/ports/atmel-samd/mpconfigport.mk
+++ b/ports/atmel-samd/mpconfigport.mk
@@ -91,3 +91,5 @@ endif # samd51
 INTERNAL_LIBM = 1
 
 USB_SERIAL_NUMBER_LENGTH = 32
+
+USB_NUM_EP = 8
diff --git a/ports/cxd56/common-hal/pulseio/PulseOut.c b/ports/cxd56/common-hal/pulseio/PulseOut.c
index 21b4c77e55..08081020f3 100644
--- a/ports/cxd56/common-hal/pulseio/PulseOut.c
+++ b/ports/cxd56/common-hal/pulseio/PulseOut.c
@@ -58,8 +58,16 @@ static bool pulseout_timer_handler(unsigned int *next_interval_us, void *arg)
     return true;
 }
 
-void common_hal_pulseio_pulseout_construct(pulseio_pulseout_obj_t *self,
-    const pulseio_pwmout_obj_t *carrier) {
+void common_hal_pulseio_pulseout_construct(pulseio_pulseout_obj_t* self,
+                                            const pulseio_pwmout_obj_t* carrier,
+                                            const mcu_pin_obj_t* pin,
+                                            uint32_t frequency,
+                                            uint16_t duty_cycle) {
+    if (!carrier || pin || frequency) {
+        mp_raise_NotImplementedError(translate("Port does not accept pins or frequency. \
+                                    Construct and pass a PWMOut Carrier instead"));
+    }
+
     if (pulse_fd < 0) {
         pulse_fd = open("/dev/timer0", O_RDONLY);
     }
diff --git a/ports/cxd56/supervisor/port.c b/ports/cxd56/supervisor/port.c
index a40d31fafb..bbd864f903 100644
--- a/ports/cxd56/supervisor/port.c
+++ b/ports/cxd56/supervisor/port.c
@@ -36,6 +36,8 @@
 #include "boards/board.h"
 
 #include "supervisor/port.h"
+#include "supervisor/background_callback.h"
+#include "supervisor/usb.h"
 #include "supervisor/shared/tick.h"
 
 #include "common-hal/microcontroller/Pin.h"
@@ -114,6 +116,11 @@ uint32_t port_get_saved_word(void) {
     return _ebss;
 }
 
+static background_callback_t callback;
+static void usb_background_do(void* unused) {
+    usb_background();
+}
+
 volatile bool _tick_enabled;
 void board_timerhook(void)
 {
@@ -121,6 +128,8 @@ void board_timerhook(void)
     if (_tick_enabled) {
         supervisor_tick();
     }
+
+    background_callback_add(&callback, usb_background_do, NULL);
 }
 
 uint64_t port_get_raw_ticks(uint8_t* subticks) {
diff --git a/ports/esp32s2/background.c b/ports/esp32s2/background.c
index 40ce9ecfdf..3160d9974e 100644
--- a/ports/esp32s2/background.c
+++ b/ports/esp32s2/background.c
@@ -35,10 +35,17 @@
 #include "shared-module/displayio/__init__.h"
 #endif
 
+#if CIRCUITPY_PULSEIO
+#include "common-hal/pulseio/PulseIn.h"
+#endif
+
 
 void port_background_task(void) {
     // Zero delay in case FreeRTOS wants to switch to something else.
     vTaskDelay(0);
+    #if CIRCUITPY_PULSEIO
+    pulsein_background();
+    #endif
 }
 
 void port_start_background_task(void) {}
diff --git a/ports/esp32s2/common-hal/neopixel_write/__init__.c b/ports/esp32s2/common-hal/neopixel_write/__init__.c
index 1fc976ec36..193d754f43 100644
--- a/ports/esp32s2/common-hal/neopixel_write/__init__.c
+++ b/ports/esp32s2/common-hal/neopixel_write/__init__.c
@@ -93,6 +93,9 @@ void common_hal_neopixel_write (const digitalio_digitalinout_obj_t* digitalinout
     // Reserve channel
     uint8_t number = digitalinout->pin->number;
     rmt_channel_t channel = esp32s2_peripherals_find_and_reserve_rmt();
+    if (channel == RMT_CHANNEL_MAX) {
+        mp_raise_RuntimeError(translate("All timers in use"));
+    }
 
     // Configure Channel
     rmt_config_t config = RMT_DEFAULT_CONFIG_TX(number, channel);
diff --git a/ports/esp32s2/common-hal/pulseio/PulseIn.c b/ports/esp32s2/common-hal/pulseio/PulseIn.c
index 65fc6631d4..f7429ec12c 100644
--- a/ports/esp32s2/common-hal/pulseio/PulseIn.c
+++ b/ports/esp32s2/common-hal/pulseio/PulseIn.c
@@ -25,51 +25,184 @@
  */
 
 #include "common-hal/pulseio/PulseIn.h"
+#include "shared-bindings/microcontroller/__init__.h"
 #include "py/runtime.h"
 
-// STATIC void pulsein_handler(uint8_t num) {
-// }
+STATIC uint8_t refcount = 0;
+STATIC pulseio_pulsein_obj_t * handles[RMT_CHANNEL_MAX];
+
+// Requires rmt.c void esp32s2_peripherals_reset_all(void) to reset
+
+STATIC void update_internal_buffer(pulseio_pulsein_obj_t* self) {
+    uint32_t length = 0;
+    rmt_item32_t *items = (rmt_item32_t *) xRingbufferReceive(self->buf_handle, &length, 0);
+    if (items) {
+        length /= 4;
+        for (size_t i=0; i < length; i++) {
+            uint16_t pos = (self->start + self->len) % self->maxlen;
+            self->buffer[pos] = items[i].duration0 * 3;
+            // Check if second item exists before incrementing
+            if (items[i].duration1) {
+                self->buffer[pos+1] = items[i].duration1 * 3;
+                if (self->len < (self->maxlen - 1)) {
+                    self->len += 2;
+                } else {
+                    self->start += 2;
+                }
+            } else {
+                if (self->len < self->maxlen) {
+                    self->len++;
+                } else {
+                    self->start++;
+                }
+            }
+        }
+        vRingbufferReturnItem(self->buf_handle, (void *) items);
+    }
+}
+
+// We can't access the RMT interrupt, so we need a global service to prevent
+// the ringbuffer from overflowing and crashing the peripheral
+void pulsein_background(void) {
+    for (size_t i = 0; i < RMT_CHANNEL_MAX; i++) {
+        if (handles[i]) {
+            update_internal_buffer(handles[i]);
+            UBaseType_t items_waiting;
+            vRingbufferGetInfo(handles[i]->buf_handle, NULL, NULL, NULL, NULL, &items_waiting);
+        }
+    }
+}
 
 void pulsein_reset(void) {
+    for (size_t i = 0; i < RMT_CHANNEL_MAX; i++) {
+        handles[i] = NULL;
+    }
+    supervisor_disable_tick();
+    refcount = 0;
 }
 
 void common_hal_pulseio_pulsein_construct(pulseio_pulsein_obj_t* self, const mcu_pin_obj_t* pin,
                                              uint16_t maxlen, bool idle_state) {
-    mp_raise_NotImplementedError(translate("PulseIn not supported on this chip"));
+    self->buffer = (uint16_t *) m_malloc(maxlen * sizeof(uint16_t), false);
+    if (self->buffer == NULL) {
+        mp_raise_msg_varg(&mp_type_MemoryError, translate("Failed to allocate RX buffer of %d bytes"), maxlen * sizeof(uint16_t));
+    }
+    self->pin = pin;
+    self->maxlen = maxlen;
+    self->idle_state = idle_state;
+    self->start = 0;
+    self->len = 0;
+    self->paused = false;
+
+    // Set pull settings
+    gpio_pullup_dis(pin->number);
+    gpio_pulldown_dis(pin->number);
+    if (idle_state) {
+        gpio_pullup_en(pin->number);
+    } else {
+        gpio_pulldown_en(pin->number);
+    }
+
+    // Find a free RMT Channel and configure it
+    rmt_channel_t channel = esp32s2_peripherals_find_and_reserve_rmt();
+    if (channel == RMT_CHANNEL_MAX) {
+        mp_raise_RuntimeError(translate("All timers in use"));
+    }
+    rmt_config_t config = RMT_DEFAULT_CONFIG_RX(pin->number, channel);
+    config.rx_config.filter_en = true;
+    config.rx_config.idle_threshold = 30000; // 30*3=90ms idle required to register a sequence
+    config.clk_div = 240; // All measurements are divided by 3 to accomodate 65ms pulses
+    rmt_config(&config);
+    rmt_driver_install(channel, 1000, 0); //TODO: pick a more specific buffer size?
+
+    // Store this object and the buffer handle for background updates
+    self->channel = channel;
+    handles[channel] = self;
+    rmt_get_ringbuf_handle(channel, &(self->buf_handle));
+
+    // start RMT RX, and enable ticks so the core doesn't turn off.
+    rmt_rx_start(channel, true);
+    supervisor_enable_tick();
+    refcount++;
 }
 
 bool common_hal_pulseio_pulsein_deinited(pulseio_pulsein_obj_t* self) {
-    return false;
+    return handles[self->channel] ? false : true;
 }
 
 void common_hal_pulseio_pulsein_deinit(pulseio_pulsein_obj_t* self) {
+    handles[self->channel] = NULL;
+    esp32s2_peripherals_free_rmt(self->channel);
+    reset_pin_number(self->pin->number);
+    refcount--;
+    if (refcount == 0) {
+        supervisor_disable_tick();
+    }
 }
 
 void common_hal_pulseio_pulsein_pause(pulseio_pulsein_obj_t* self) {
+    self->paused = true;
+    rmt_rx_stop(self->channel);
 }
 
 void common_hal_pulseio_pulsein_resume(pulseio_pulsein_obj_t* self, uint16_t trigger_duration) {
+    // Make sure we're paused.
+    if ( !self->paused ) {
+        common_hal_pulseio_pulsein_pause(self);
+    }
+
+    if (trigger_duration > 0) {
+        gpio_set_direction(self->pin->number, GPIO_MODE_DEF_OUTPUT);
+        gpio_set_level(self->pin->number, !self->idle_state);
+        common_hal_mcu_delay_us((uint32_t)trigger_duration);
+        gpio_set_level(self->pin->number, self->idle_state);
+        gpio_set_direction(self->pin->number, GPIO_MODE_INPUT); // should revert to pull direction
+    }
+
+    self->paused = false;
+    rmt_rx_start(self->channel, false);
 }
 
 void common_hal_pulseio_pulsein_clear(pulseio_pulsein_obj_t* self) {
+    // Buffer only updates in BG tasks or fetches, so no extra protection is needed
+    self->start = 0;
+    self->len = 0;
 }
 
 uint16_t common_hal_pulseio_pulsein_get_item(pulseio_pulsein_obj_t* self, int16_t index) {
-    return false;
+    update_internal_buffer(self);
+    if (index < 0) {
+        index += self->len;
+    }
+    if (index < 0 || index >= self->len) {
+        mp_raise_IndexError(translate("index out of range"));
+    }
+    uint16_t value = self->buffer[(self->start + index) % self->maxlen];
+    return value;
 }
 
 uint16_t common_hal_pulseio_pulsein_popleft(pulseio_pulsein_obj_t* self) {
-    return false;
+    update_internal_buffer(self);
+
+    if (self->len == 0) {
+        mp_raise_IndexError(translate("pop from an empty PulseIn"));
+    }
+
+    uint16_t value = self->buffer[self->start];
+    self->start = (self->start + 1) % self->maxlen;
+    self->len--;
+
+    return value;
 }
 
 uint16_t common_hal_pulseio_pulsein_get_maxlen(pulseio_pulsein_obj_t* self) {
-    return false;
+    return self->maxlen;
 }
 
 bool common_hal_pulseio_pulsein_get_paused(pulseio_pulsein_obj_t* self) {
-    return false;
+    return self->paused;
 }
 
 uint16_t common_hal_pulseio_pulsein_get_len(pulseio_pulsein_obj_t* self) {
-    return false;
+    return self->len;
 }
diff --git a/ports/esp32s2/common-hal/pulseio/PulseIn.h b/ports/esp32s2/common-hal/pulseio/PulseIn.h
index b317c516c1..97d70d4b03 100644
--- a/ports/esp32s2/common-hal/pulseio/PulseIn.h
+++ b/ports/esp32s2/common-hal/pulseio/PulseIn.h
@@ -30,24 +30,27 @@
 #include "common-hal/microcontroller/Pin.h"
 
 #include "py/obj.h"
+#include "driver/rmt.h"
+#include "rmt.h"
 
 typedef struct {
     mp_obj_base_t base;
 
     const mcu_pin_obj_t* pin;
+    rmt_channel_t channel;
     bool idle_state;
     bool paused;
-    volatile bool first_edge;
+
+    RingbufHandle_t buf_handle;
 
     uint16_t* buffer;
     uint16_t maxlen;
 
     volatile uint16_t start;
     volatile uint16_t len;
-    volatile uint32_t last_overflow;
-    volatile uint16_t last_count;
 } pulseio_pulsein_obj_t;
 
 void pulsein_reset(void);
+void pulsein_background(void);
 
 #endif // MICROPY_INCLUDED_ESP32S2_COMMON_HAL_PULSEIO_PULSEIN_H
diff --git a/ports/esp32s2/common-hal/pulseio/PulseOut.c b/ports/esp32s2/common-hal/pulseio/PulseOut.c
index c448c578df..d3c163ca8b 100644
--- a/ports/esp32s2/common-hal/pulseio/PulseOut.c
+++ b/ports/esp32s2/common-hal/pulseio/PulseOut.c
@@ -29,32 +29,63 @@
 #include "shared-bindings/pulseio/PWMOut.h"
 #include "py/runtime.h"
 
-// STATIC void turn_on(pulseio_pulseout_obj_t *pulseout) {
-// }
-
-// STATIC void turn_off(pulseio_pulseout_obj_t *pulseout) {
-// }
-
-// STATIC void start_timer(void) {
-// }
-
-// STATIC void pulseout_event_handler(void) {
-// }
-
-void pulseout_reset() {
-}
+// Requires rmt.c void esp32s2_peripherals_reset_all(void) to reset
 
 void common_hal_pulseio_pulseout_construct(pulseio_pulseout_obj_t* self,
-                                           const pulseio_pwmout_obj_t* carrier) {
-    mp_raise_NotImplementedError(translate("PulseOut not supported on this chip"));
+                                            const pulseio_pwmout_obj_t* carrier,
+                                            const mcu_pin_obj_t* pin,
+                                            uint32_t frequency,
+                                            uint16_t duty_cycle) {
+    if (carrier || !pin || !frequency) {
+        mp_raise_NotImplementedError(translate("Port does not accept PWM carrier. \
+                                    Pass a pin, frequency and duty cycle instead"));
+    }
+
+    rmt_channel_t channel = esp32s2_peripherals_find_and_reserve_rmt();
+    if (channel == RMT_CHANNEL_MAX) {
+        mp_raise_RuntimeError(translate("All timers in use"));
+    }
+
+    // Configure Channel
+    rmt_config_t config = RMT_DEFAULT_CONFIG_TX(pin->number, channel);
+    config.tx_config.carrier_en = true;
+    config.tx_config.carrier_duty_percent = (duty_cycle * 100) / (1<<16);
+    config.tx_config.carrier_freq_hz = frequency;
+    config.clk_div = 80;
+
+    rmt_config(&config);
+    rmt_driver_install(channel, 0, 0);
+
+    self->channel = channel;
 }
 
 bool common_hal_pulseio_pulseout_deinited(pulseio_pulseout_obj_t* self) {
-    return false;
+    return (self->channel == RMT_CHANNEL_MAX);
 }
 
 void common_hal_pulseio_pulseout_deinit(pulseio_pulseout_obj_t* self) {
+    esp32s2_peripherals_free_rmt(self->channel);
+    self->channel = RMT_CHANNEL_MAX;
+
 }
 
 void common_hal_pulseio_pulseout_send(pulseio_pulseout_obj_t* self, uint16_t* pulses, uint16_t length) {
+    rmt_item32_t items[length];
+
+    // Circuitpython allows 16 bit pulse values, while ESP32 only allows 15 bits
+    // Thus, we use entire items for one pulse, rather than switching inside each item
+    for (size_t i = 0; i < length; i++) {
+        // Setting the RMT duration to 0 has undefined behavior, so avoid that pre-emptively.
+        if (pulses[i] == 0) {
+            pulses[i] = 1;
+        }
+        uint32_t level = (i % 2) ? 0 : 1;
+        const rmt_item32_t item = {{{ (pulses[i] & 0x8000 ? 0x7FFF : 1), level, (pulses[i] & 0x7FFF), level}}};
+        items[i] = item;
+    }
+
+    rmt_write_items(self->channel, items, length, true);
+    while (rmt_wait_tx_done(self->channel, 0) != ESP_OK) {
+        RUN_BACKGROUND_TASKS;
+    }
 }
diff --git a/ports/esp32s2/common-hal/pulseio/PulseOut.h b/ports/esp32s2/common-hal/pulseio/PulseOut.h
index f465d00792..5139059926 100644
--- a/ports/esp32s2/common-hal/pulseio/PulseOut.h
+++ b/ports/esp32s2/common-hal/pulseio/PulseOut.h
@@ -29,14 +29,14 @@
 
 #include "common-hal/microcontroller/Pin.h"
 #include "common-hal/pulseio/PWMOut.h"
+#include "driver/rmt.h"
+#include "rmt.h"
 
 #include "py/obj.h"
 
 typedef struct {
     mp_obj_base_t base;
-    pulseio_pwmout_obj_t *pwmout;
+    rmt_channel_t channel;
 } pulseio_pulseout_obj_t;
 
-void pulseout_reset(void);
-
 #endif // MICROPY_INCLUDED_ESP32S2_COMMON_HAL_PULSEIO_PULSEOUT_H
diff --git a/ports/esp32s2/mpconfigport.h b/ports/esp32s2/mpconfigport.h
index d340bb4805..07f83434af 100644
--- a/ports/esp32s2/mpconfigport.h
+++ b/ports/esp32s2/mpconfigport.h
@@ -28,19 +28,18 @@
 #ifndef ESP32S2_MPCONFIGPORT_H__
 #define ESP32S2_MPCONFIGPORT_H__
 
-#define CIRCUITPY_INTERNAL_NVM_SIZE         (0)
-#define MICROPY_NLR_THUMB                   (0)
+#define CIRCUITPY_INTERNAL_NVM_SIZE     (0)
+#define MICROPY_NLR_THUMB               (0)
 
-#define MICROPY_PY_UJSON            (0)
-#define MICROPY_USE_INTERNAL_PRINTF      (0)
+#define MICROPY_PY_UJSON                (0)
+#define MICROPY_USE_INTERNAL_PRINTF     (0)
 
 #include "py/circuitpy_mpconfig.h"
 
-
 #define MICROPY_PORT_ROOT_POINTERS \
 	CIRCUITPY_COMMON_ROOT_POINTERS
-#define MICROPY_NLR_SETJMP                  (1)
-#define CIRCUITPY_DEFAULT_STACK_SIZE        0x6000
+#define MICROPY_NLR_SETJMP              (1)
+#define CIRCUITPY_DEFAULT_STACK_SIZE    (0x6000)
 
 
 #endif  // __INCLUDED_ESP32S2_MPCONFIGPORT_H
diff --git a/ports/esp32s2/peripherals/rmt.c b/ports/esp32s2/peripherals/rmt.c
index f17957c1c4..b7629dbd5c 100644
--- a/ports/esp32s2/peripherals/rmt.c
+++ b/ports/esp32s2/peripherals/rmt.c
@@ -29,6 +29,14 @@
 
 bool rmt_reserved_channels[RMT_CHANNEL_MAX];
 
+void esp32s2_peripherals_rmt_reset(void) {
+    for (size_t i = 0; i < RMT_CHANNEL_MAX; i++) {
+        if (rmt_reserved_channels[i]) {
+            esp32s2_peripherals_free_rmt(i);
+        }
+    }
+}
+
 rmt_channel_t esp32s2_peripherals_find_and_reserve_rmt(void) {
     for (size_t i = 0; i < RMT_CHANNEL_MAX; i++) {
         if (!rmt_reserved_channels[i]) {
@@ -36,8 +44,8 @@ rmt_channel_t esp32s2_peripherals_find_and_reserve_rmt(void) {
             return i;
         }
     }
-    mp_raise_RuntimeError(translate("All timers in use"));
-    return false;
+    // Returning the max indicates a reservation failure.
+    return RMT_CHANNEL_MAX;
 }
 
 void esp32s2_peripherals_free_rmt(rmt_channel_t chan) {
diff --git a/ports/esp32s2/peripherals/rmt.h b/ports/esp32s2/peripherals/rmt.h
index 4741a5bc59..01ed09907a 100644
--- a/ports/esp32s2/peripherals/rmt.h
+++ b/ports/esp32s2/peripherals/rmt.h
@@ -31,6 +31,7 @@
 #include "driver/rmt.h"
 #include <stdint.h>
 
+void esp32s2_peripherals_rmt_reset(void);
 rmt_channel_t esp32s2_peripherals_find_and_reserve_rmt(void);
 void esp32s2_peripherals_free_rmt(rmt_channel_t chan);
 
diff --git a/ports/esp32s2/supervisor/port.c b/ports/esp32s2/supervisor/port.c
index e4767e5146..46590b5513 100644
--- a/ports/esp32s2/supervisor/port.c
+++ b/ports/esp32s2/supervisor/port.c
@@ -39,9 +39,12 @@
 #include "common-hal/busio/SPI.h"
 #include "common-hal/busio/UART.h"
 #include "common-hal/pulseio/PWMOut.h"
+#include "common-hal/pulseio/PulseIn.h"
 #include "supervisor/memory.h"
 #include "supervisor/shared/tick.h"
 
+#include "rmt.h"
+
 STATIC esp_timer_handle_t _tick_timer;
 
 void tick_timer_cb(void* arg) {
@@ -66,7 +69,9 @@ void reset_port(void) {
     vTaskDelay(4);
 
 #if CIRCUITPY_PULSEIO
+    esp32s2_peripherals_rmt_reset();
     pwmout_reset();
+    pulsein_reset();
 #endif
 #if CIRCUITPY_BUSIO
     i2c_reset();
diff --git a/ports/mimxrt10xx/common-hal/pulseio/PulseOut.c b/ports/mimxrt10xx/common-hal/pulseio/PulseOut.c
index ffa885688a..3aefd87662 100644
--- a/ports/mimxrt10xx/common-hal/pulseio/PulseOut.c
+++ b/ports/mimxrt10xx/common-hal/pulseio/PulseOut.c
@@ -94,7 +94,10 @@ void pulseout_reset() {
 }
 
 void common_hal_pulseio_pulseout_construct(pulseio_pulseout_obj_t* self,
-                                            const pulseio_pwmout_obj_t* carrier) {
+                                            const pulseio_pwmout_obj_t* carrier,
+                                            const mcu_pin_obj_t* pin,
+                                            uint32_t frequency,
+                                            uint16_t duty_cycle) {
 //    if (refcount == 0) {
 //        // Find a spare timer.
 //        Tc *tc = NULL;
diff --git a/ports/nrf/common-hal/pulseio/PulseOut.c b/ports/nrf/common-hal/pulseio/PulseOut.c
index 270cb45d6d..bdc5cfbef5 100644
--- a/ports/nrf/common-hal/pulseio/PulseOut.c
+++ b/ports/nrf/common-hal/pulseio/PulseOut.c
@@ -100,7 +100,15 @@ void pulseout_reset() {
 }
 
 void common_hal_pulseio_pulseout_construct(pulseio_pulseout_obj_t* self,
-                                           const pulseio_pwmout_obj_t* carrier) {
+                                            const pulseio_pwmout_obj_t* carrier,
+                                            const mcu_pin_obj_t* pin,
+                                            uint32_t frequency,
+                                            uint16_t duty_cycle) {
+    if (!carrier || pin || frequency) {
+        mp_raise_NotImplementedError(translate("Port does not accept pins or frequency. \
+                                    Construct and pass a PWMOut Carrier instead"));
+    }
+
     if (refcount == 0) {
         timer = nrf_peripherals_allocate_timer_or_throw();
     }
diff --git a/ports/stm/common-hal/pulseio/PulseOut.c b/ports/stm/common-hal/pulseio/PulseOut.c
index bcc25d8177..eec1049dd2 100644
--- a/ports/stm/common-hal/pulseio/PulseOut.c
+++ b/ports/stm/common-hal/pulseio/PulseOut.c
@@ -113,7 +113,15 @@ void pulseout_reset() {
 }
 
 void common_hal_pulseio_pulseout_construct(pulseio_pulseout_obj_t* self,
-                                           const pulseio_pwmout_obj_t* carrier) {
+                                            const pulseio_pwmout_obj_t* carrier,
+                                            const mcu_pin_obj_t* pin,
+                                            uint32_t frequency,
+                                            uint16_t duty_cycle) {
+    if (!carrier || pin || frequency) {
+        mp_raise_NotImplementedError(translate("Port does not accept pins or frequency. \
+                                    Construct and pass a PWMOut Carrier instead"));
+    }
+
     // Add to active PulseOuts
     refcount++;
     TIM_TypeDef * tim_instance = stm_peripherals_find_timer();
diff --git a/shared-bindings/pulseio/PulseOut.c b/shared-bindings/pulseio/PulseOut.c
index 3d35f05445..3fd722558e 100644
--- a/shared-bindings/pulseio/PulseOut.c
+++ b/shared-bindings/pulseio/PulseOut.c
@@ -64,20 +64,29 @@
 //|           pulse.send(pulses)"""
 //|         ...
 //|
-STATIC mp_obj_t pulseio_pulseout_make_new(const mp_obj_type_t *type, size_t n_args, const mp_obj_t *args, mp_map_t *kw_args) {
-    mp_arg_check_num(n_args, kw_args, 1, 1, false);
-    mp_obj_t carrier_obj = args[0];
+STATIC mp_obj_t pulseio_pulseout_make_new(const mp_obj_type_t *type, size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
 
-    if (!MP_OBJ_IS_TYPE(carrier_obj, &pulseio_pwmout_type)) {
-        mp_raise_TypeError_varg(translate("Expected a %q"), pulseio_pwmout_type.name);
-    }
-
-    // create Pulse object from the given pin
     pulseio_pulseout_obj_t *self = m_new_obj(pulseio_pulseout_obj_t);
     self->base.type = &pulseio_pulseout_type;
 
-    common_hal_pulseio_pulseout_construct(self, (pulseio_pwmout_obj_t *)MP_OBJ_TO_PTR(carrier_obj));
-
+    mp_obj_t carrier_obj = pos_args[0];
+    if (MP_OBJ_IS_TYPE(carrier_obj, &pulseio_pwmout_type)) {
+        // Use a PWMOut Carrier
+        mp_arg_check_num(n_args, kw_args, 1, 1, false);
+        common_hal_pulseio_pulseout_construct(self, (pulseio_pwmout_obj_t *)MP_OBJ_TO_PTR(carrier_obj), NULL, 0, 0);
+    } else {
+        // Use a Pin, frequency, and duty cycle
+        enum { ARG_pin, ARG_frequency};
+        static const mp_arg_t allowed_args[] = {
+            { MP_QSTR_pin, MP_ARG_REQUIRED | MP_ARG_OBJ },
+            { MP_QSTR_frequency, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 38000} },
+            { MP_QSTR_duty_cycle, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 1<<15} },
+        };
+        mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
+        mp_arg_parse_all(n_args, pos_args, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
+        const mcu_pin_obj_t* pin = validate_obj_is_free_pin(args[ARG_pin].u_obj);
+        common_hal_pulseio_pulseout_construct(self, NULL, pin, args[ARG_frequency].u_int, args[ARG_frequency].u_int);
+    }
     return MP_OBJ_FROM_PTR(self);
 }
 
diff --git a/shared-bindings/pulseio/PulseOut.h b/shared-bindings/pulseio/PulseOut.h
index 390910ff62..9d4778e93d 100644
--- a/shared-bindings/pulseio/PulseOut.h
+++ b/shared-bindings/pulseio/PulseOut.h
@@ -34,7 +34,11 @@
 extern const mp_obj_type_t pulseio_pulseout_type;
 
 extern void common_hal_pulseio_pulseout_construct(pulseio_pulseout_obj_t* self,
-    const pulseio_pwmout_obj_t* carrier);
+                                            const pulseio_pwmout_obj_t* carrier,
+                                            const mcu_pin_obj_t* pin,
+                                            uint32_t frequency,
+                                            uint16_t duty_cycle);
+
 extern void common_hal_pulseio_pulseout_deinit(pulseio_pulseout_obj_t* self);
 extern bool common_hal_pulseio_pulseout_deinited(pulseio_pulseout_obj_t* self);
 extern void common_hal_pulseio_pulseout_send(pulseio_pulseout_obj_t* self,
diff --git a/supervisor/supervisor.mk b/supervisor/supervisor.mk
index fdfaa1bf84..e81c51a88c 100644
--- a/supervisor/supervisor.mk
+++ b/supervisor/supervisor.mk
@@ -171,6 +171,10 @@ ifndef USB_MIDI_EP_NUM_IN
 USB_MIDI_EP_NUM_IN = 0
 endif
 
+ifndef USB_NUM_EP
+USB_NUM_EP = 0
+endif
+
 USB_DESCRIPTOR_ARGS = \
 	--manufacturer $(USB_MANUFACTURER)\
 	--product $(USB_PRODUCT)\
@@ -180,6 +184,7 @@ USB_DESCRIPTOR_ARGS = \
 	--interface_name $(USB_INTERFACE_NAME)\
 	--devices $(USB_DEVICES)\
 	--hid_devices $(USB_HID_DEVICES)\
+	--max_ep $(USB_NUM_EP) \
 	--cdc_ep_num_notification $(USB_CDC_EP_NUM_NOTIFICATION)\
 	--cdc_ep_num_data_out $(USB_CDC_EP_NUM_DATA_OUT)\
 	--cdc_ep_num_data_in $(USB_CDC_EP_NUM_DATA_IN)\
diff --git a/tools/gen_usb_descriptor.py b/tools/gen_usb_descriptor.py
index fb91fd3345..baee8cad7b 100644
--- a/tools/gen_usb_descriptor.py
+++ b/tools/gen_usb_descriptor.py
@@ -62,6 +62,8 @@ parser.add_argument('--midi_ep_num_out', type=int, default=0,
                     help='endpoint number of MIDI OUT')
 parser.add_argument('--midi_ep_num_in', type=int, default=0,
                     help='endpoint number of MIDI IN')
+parser.add_argument('--max_ep', type=int, default=0,
+                    help='total number of endpoints available')
 parser.add_argument('--output_c_file', type=argparse.FileType('w', encoding='UTF-8'), required=True)
 parser.add_argument('--output_h_file', type=argparse.FileType('w', encoding='UTF-8'), required=True)
 
@@ -376,6 +378,15 @@ if 'AUDIO' in args.devices:
 # interface cross-references.
 interfaces = util.join_interfaces(interfaces_to_join, renumber_endpoints=args.renumber_endpoints)
 
+if args.max_ep != 0:
+    for interface in interfaces:
+        for subdescriptor in interface.subdescriptors:
+            endpoint_address = getattr(subdescriptor, 'bEndpointAddress', 0) & 0x7f
+            if endpoint_address > args.max_ep:
+                raise ValueError("Endpoint address %d of %s may not exceed %d" % (endpoint_address & 0x7f, interface.description, args.max_ep))
+else:
+    print("Unable to check whether maximum number of endpoints is respected", file=sys.stderr)
+
 # Now adjust the CDC interface cross-references.
 
 cdc_union.bMasterInterface = cdc_comm_interface.bInterfaceNumber