diff --git a/locale/circuitpython.pot b/locale/circuitpython.pot
index b98e0e2132..d9d5d6e17d 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: 2020-08-17 10:10-0400\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"
@@ -1334,7 +1334,7 @@ msgstr ""
 #: ports/stm/common-hal/pulseio/PulseOut.c
 msgid ""
 "Port does not accept pins or frequency.                                     "
-"Construct and pass a PWM Carrier instead"
+"Construct and pass a PWMOut Carrier instead"
 msgstr ""
 
 #: shared-bindings/_bleio/Adapter.c
diff --git a/ports/atmel-samd/common-hal/pulseio/PulseOut.c b/ports/atmel-samd/common-hal/pulseio/PulseOut.c
index de2f7b8d2a..b53c8da2ba 100644
--- a/ports/atmel-samd/common-hal/pulseio/PulseOut.c
+++ b/ports/atmel-samd/common-hal/pulseio/PulseOut.c
@@ -102,7 +102,7 @@ void common_hal_pulseio_pulseout_construct(pulseio_pulseout_obj_t* self,
                                             uint16_t duty_cycle) {
     if (!carrier || pin || frequency) {
         mp_raise_NotImplementedError(translate("Port does not accept pins or frequency. \
-                                    Construct and pass a PWM Carrier instead"));
+                                    Construct and pass a PWMOut Carrier instead"));
     }
 
     if (refcount == 0) {
diff --git a/ports/cxd56/common-hal/pulseio/PulseOut.c b/ports/cxd56/common-hal/pulseio/PulseOut.c
index 2851a04658..08081020f3 100644
--- a/ports/cxd56/common-hal/pulseio/PulseOut.c
+++ b/ports/cxd56/common-hal/pulseio/PulseOut.c
@@ -65,7 +65,7 @@ void common_hal_pulseio_pulseout_construct(pulseio_pulseout_obj_t* self,
                                             uint16_t duty_cycle) {
     if (!carrier || pin || frequency) {
         mp_raise_NotImplementedError(translate("Port does not accept pins or frequency. \
-                                    Construct and pass a PWM Carrier instead"));
+                                    Construct and pass a PWMOut Carrier instead"));
     }
 
     if (pulse_fd < 0) {
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 d741628305..f7429ec12c 100644
--- a/ports/esp32s2/common-hal/pulseio/PulseIn.c
+++ b/ports/esp32s2/common-hal/pulseio/PulseIn.c
@@ -105,6 +105,9 @@ void common_hal_pulseio_pulsein_construct(pulseio_pulsein_obj_t* self, const mcu
 
     // 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
diff --git a/ports/esp32s2/common-hal/pulseio/PulseOut.c b/ports/esp32s2/common-hal/pulseio/PulseOut.c
index 463443ef0c..a07ec39dc2 100644
--- a/ports/esp32s2/common-hal/pulseio/PulseOut.c
+++ b/ports/esp32s2/common-hal/pulseio/PulseOut.c
@@ -42,6 +42,9 @@ void common_hal_pulseio_pulseout_construct(pulseio_pulseout_obj_t* self,
     }
 
     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);
@@ -82,5 +85,7 @@ void common_hal_pulseio_pulseout_send(pulseio_pulseout_obj_t* self, uint16_t* pu
     }
 
     rmt_write_items(self->channel, items, length, true);
-    rmt_wait_tx_done(self->channel, pdMS_TO_TICKS(100));
+    while (rmt_wait_tx_done(self->channel, 0) != ESP_OK) {
+        RUN_BACKGROUND_TASKS();
+    }
 }
diff --git a/ports/esp32s2/peripherals/rmt.c b/ports/esp32s2/peripherals/rmt.c
index 16605edf5e..b7629dbd5c 100644
--- a/ports/esp32s2/peripherals/rmt.c
+++ b/ports/esp32s2/peripherals/rmt.c
@@ -44,8 +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/nrf/common-hal/pulseio/PulseOut.c b/ports/nrf/common-hal/pulseio/PulseOut.c
index 9f5efcfdc6..bdc5cfbef5 100644
--- a/ports/nrf/common-hal/pulseio/PulseOut.c
+++ b/ports/nrf/common-hal/pulseio/PulseOut.c
@@ -106,7 +106,7 @@ void common_hal_pulseio_pulseout_construct(pulseio_pulseout_obj_t* self,
                                             uint16_t duty_cycle) {
     if (!carrier || pin || frequency) {
         mp_raise_NotImplementedError(translate("Port does not accept pins or frequency. \
-                                    Construct and pass a PWM Carrier instead"));
+                                    Construct and pass a PWMOut Carrier instead"));
     }
 
     if (refcount == 0) {
diff --git a/ports/stm/common-hal/pulseio/PulseOut.c b/ports/stm/common-hal/pulseio/PulseOut.c
index 33311fd53d..eec1049dd2 100644
--- a/ports/stm/common-hal/pulseio/PulseOut.c
+++ b/ports/stm/common-hal/pulseio/PulseOut.c
@@ -119,7 +119,7 @@ void common_hal_pulseio_pulseout_construct(pulseio_pulseout_obj_t* self,
                                             uint16_t duty_cycle) {
     if (!carrier || pin || frequency) {
         mp_raise_NotImplementedError(translate("Port does not accept pins or frequency. \
-                                    Construct and pass a PWM Carrier instead"));
+                                    Construct and pass a PWMOut Carrier instead"));
     }
 
     // Add to active PulseOuts
diff --git a/shared-bindings/pulseio/PulseOut.c b/shared-bindings/pulseio/PulseOut.c
index 2adbc3cf6a..3fd722558e 100644
--- a/shared-bindings/pulseio/PulseOut.c
+++ b/shared-bindings/pulseio/PulseOut.c
@@ -71,11 +71,11 @@ STATIC mp_obj_t pulseio_pulseout_make_new(const mp_obj_type_t *type, size_t n_ar
 
     mp_obj_t carrier_obj = pos_args[0];
     if (MP_OBJ_IS_TYPE(carrier_obj, &pulseio_pwmout_type)) {
-        // PWM Carrier
+        // 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 {
-        // Pin and Frequency
+        // 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 },