diff --git a/ports/esp32s2/common-hal/busio/I2C.c b/ports/esp32s2/common-hal/busio/I2C.c
index 391d7323c5..74b3896fc2 100644
--- a/ports/esp32s2/common-hal/busio/I2C.c
+++ b/ports/esp32s2/common-hal/busio/I2C.c
@@ -90,8 +90,10 @@ void common_hal_busio_i2c_construct(busio_i2c_obj_t *self,
 #endif
 
 
-    self->semaphore_handle = xSemaphoreCreateBinaryStatic(&self->semaphore);
-    xSemaphoreGive(self->semaphore_handle);
+    if (xSemaphoreCreateBinaryStatic(&self->semaphore) != &self->semaphore) {
+        mp_raise_RuntimeError(translate("Unable to create lock"));
+    }
+    xSemaphoreGive(&self->semaphore);
     self->sda_pin = sda;
     self->scl_pin = scl;
     self->i2c_num = I2C_NUM_MAX;
@@ -161,7 +163,7 @@ bool common_hal_busio_i2c_probe(busio_i2c_obj_t *self, uint8_t addr) {
 }
 
 bool common_hal_busio_i2c_try_lock(busio_i2c_obj_t *self) {
-    self->has_lock = xSemaphoreTake(self->semaphore_handle, 0) == pdTRUE;
+    self->has_lock = xSemaphoreTake(&self->semaphore, 0) == pdTRUE;
     return self->has_lock;
 }
 
@@ -170,7 +172,7 @@ bool common_hal_busio_i2c_has_lock(busio_i2c_obj_t *self) {
 }
 
 void common_hal_busio_i2c_unlock(busio_i2c_obj_t *self) {
-    xSemaphoreGive(self->semaphore_handle);
+    xSemaphoreGive(&self->semaphore);
     self->has_lock = false;
 }
 
diff --git a/ports/esp32s2/common-hal/busio/I2C.h b/ports/esp32s2/common-hal/busio/I2C.h
index d90fb2713a..24a3fd4951 100644
--- a/ports/esp32s2/common-hal/busio/I2C.h
+++ b/ports/esp32s2/common-hal/busio/I2C.h
@@ -40,7 +40,6 @@ typedef struct {
     const mcu_pin_obj_t* sda_pin;
     i2c_port_t i2c_num;
     StaticSemaphore_t semaphore;
-    SemaphoreHandle_t semaphore_handle;
     bool has_lock;
 } busio_i2c_obj_t;
 
diff --git a/ports/esp32s2/common-hal/busio/SPI.c b/ports/esp32s2/common-hal/busio/SPI.c
index 73d7d0595e..a22075cd59 100644
--- a/ports/esp32s2/common-hal/busio/SPI.c
+++ b/ports/esp32s2/common-hal/busio/SPI.c
@@ -209,9 +209,6 @@ void common_hal_busio_spi_construct(busio_spi_obj_t *self,
 
     hal->io_mode = SPI_LL_IO_MODE_NORMAL;
 
-    // This must be set after spi_hal_init.
-    hal->timing_conf = &self->timing_conf;
-
     common_hal_busio_spi_configure(self, 250000, 0, 0, 8);
 }
 
@@ -261,6 +258,7 @@ bool common_hal_busio_spi_configure(busio_spi_obj_t *self,
     self->phase = phase;
     self->bits = bits;
     self->target_frequency = baudrate;
+    self->hal_context.timing_conf = &self->timing_conf;
     esp_err_t result =  spi_hal_get_clock_conf(&self->hal_context,
                                                self->target_frequency,
                                                128 /* duty_cycle */,
@@ -315,6 +313,8 @@ bool common_hal_busio_spi_transfer(busio_spi_obj_t *self, const uint8_t *data_ou
     spi_hal_context_t* hal = &self->hal_context;
     hal->send_buffer = NULL;
     hal->rcv_buffer = NULL;
+    // Reset timing_conf in case we've moved since the last time we used it.
+    hal->timing_conf = &self->timing_conf;
     // This rounds up.
     size_t dma_count = (len + LLDESC_MAX_NUM_PER_DESC - 1) / LLDESC_MAX_NUM_PER_DESC;
     for (size_t i = 0; i < dma_count; i++) {
diff --git a/ports/esp32s2/common-hal/busio/UART.c b/ports/esp32s2/common-hal/busio/UART.c
index f73f5c993d..b0162adba9 100644
--- a/ports/esp32s2/common-hal/busio/UART.c
+++ b/ports/esp32s2/common-hal/busio/UART.c
@@ -249,6 +249,9 @@ size_t common_hal_busio_uart_read(busio_uart_obj_t *self, uint8_t *data, size_t
     while (supervisor_ticks_ms64() - start_ticks <= self->timeout_ms) {
         // Read as many chars as we can right now, up to len.
         size_t num_read = uart_read_bytes(self->uart_num, data, len, 0);
+        if (num_read < 0) {
+            break;
+        }
 
         // Advance pointer in data buffer, and decrease how many chars left to read.
         data += num_read;