diff --git a/bricks/_common/arm_none_eabi.mk b/bricks/_common/arm_none_eabi.mk
index 9b83b488a..2f8393053 100644
--- a/bricks/_common/arm_none_eabi.mk
+++ b/bricks/_common/arm_none_eabi.mk
@@ -253,24 +253,22 @@ PY_EXTRA_SRC_C += $(addprefix bricks/_common/,\
 	micropython.c \
 	)
 
-ifeq ($(PB_MCU_FAMILY),STM32)
-PY_EXTRA_SRC_C += $(addprefix bricks/_common_stm32/,\
+# TODO: NXT should eventually use the same mphalport.c as well.
+ifeq ($(PB_MCU_FAMILY),AT91SAM7)
+PY_EXTRA_SRC_C += $(addprefix bricks/nxt/,\
 	mphalport.c \
 	)
-
-ifeq ($(PB_MCU_SERIES),F0)
-SRC_S += shared/runtime/gchelper_thumb1.s
 else
-SRC_S += shared/runtime/gchelper_thumb2.s
-endif
-endif
-
-ifeq ($(PB_MCU_FAMILY),AT91SAM7)
-PY_EXTRA_SRC_C += $(addprefix bricks/nxt/,\
+PY_EXTRA_SRC_C += $(addprefix bricks/_common/,\
 	mphalport.c \
 	)
+endif
 
+# Not all MCUs support thumb2 instructions.
+ifeq ($(PB_MCU_SERIES),$(filter $(PB_MCU_SERIES),AT91SAM7 F0 TIAM1808))
 SRC_S += shared/runtime/gchelper_thumb1.s
+else
+SRC_S += shared/runtime/gchelper_thumb2.s
 endif
 
 # Skipping uart_irda_cir.c, gpio_v2.c, and hsi2c.c usbphyGS70.c, which
@@ -316,14 +314,6 @@ EV3_SRC_S = $(addprefix lib/pbio/platform/ev3/,\
 	start.S \
 	)
 
-ifeq ($(PB_MCU_FAMILY),TIAM1808)
-PY_EXTRA_SRC_C += $(addprefix bricks/ev3/,\
-	mphalport.c \
-	)
-
-SRC_S += shared/runtime/gchelper_thumb1.s
-endif
-
 # STM32 Bluetooth stack
 
 BLUENRG_SRC_C = $(addprefix lib/BlueNRG-MS/hci/,\
diff --git a/bricks/_common_stm32/mphalport.c b/bricks/_common/mphalport.c
similarity index 100%
rename from bricks/_common_stm32/mphalport.c
rename to bricks/_common/mphalport.c
diff --git a/bricks/ev3/mphalport.c b/bricks/ev3/mphalport.c
deleted file mode 100644
index 7f869fc36..000000000
--- a/bricks/ev3/mphalport.c
+++ /dev/null
@@ -1,82 +0,0 @@
-// SPDX-License-Identifier: MIT
-// Copyright (c) 2018-2021 The Pybricks Authors
-// Copyright (c) 2013, 2014 Damien P. George
-
-#include <stdint.h>
-
-#include <contiki.h>
-
-#include <pbdrv/config.h>
-#include <pbdrv/clock.h>
-#include <pbio/main.h>
-#include <pbsys/host.h>
-
-#include "py/runtime.h"
-#include "py/mphal.h"
-#include "py/mpconfig.h"
-#include "py/stream.h"
-
-// Core delay function that does an efficient sleep and may switch thread context.
-// We must have the GIL.
-void mp_hal_delay_ms(mp_uint_t Delay) {
-    // Use systick counter to do the delay
-    uint32_t start = pbdrv_clock_get_ms();
-    // Wraparound of tick is taken care of by 2's complement arithmetic.
-    do {
-        // This macro will execute the necessary idle behaviour.  It may
-        // raise an exception, switch threads or enter sleep mode (waiting for
-        // (at least) the SysTick interrupt).
-        MICROPY_EVENT_POLL_HOOK
-    } while (pbdrv_clock_get_ms() - start < Delay);
-}
-
-uintptr_t mp_hal_stdio_poll(uintptr_t poll_flags) {
-    uintptr_t ret = 0;
-
-    if ((poll_flags & MP_STREAM_POLL_RD) && pbsys_host_stdin_get_available()) {
-        ret |= MP_STREAM_POLL_RD;
-    }
-
-    return ret;
-}
-
-// Receive single character
-int mp_hal_stdin_rx_chr(void) {
-    uint32_t size;
-    uint8_t c;
-
-    // wait for rx interrupt
-    while (size = 1, pbsys_host_stdin_read(&c, &size) != PBIO_SUCCESS) {
-        MICROPY_EVENT_POLL_HOOK
-    }
-
-    return c;
-}
-
-// Send string of given length
-mp_uint_t mp_hal_stdout_tx_strn(const char *str, size_t len) {
-    size_t remaining = len;
-
-    while (remaining) {
-        uint32_t size = remaining;
-        pbio_error_t err = pbsys_host_stdout_write((const uint8_t *)str, &size);
-        if (err == PBIO_SUCCESS) {
-            str += size;
-            remaining -= size;
-        } else if (err != PBIO_ERROR_AGAIN) {
-            // Ignoring error for now. This means stdout is lost if Bluetooth/USB
-            // is disconnected.
-            return len - remaining;
-        }
-
-        MICROPY_EVENT_POLL_HOOK
-    }
-
-    return len;
-}
-
-void mp_hal_stdout_tx_flush(void) {
-    while (!pbsys_host_tx_is_idle()) {
-        MICROPY_EVENT_POLL_HOOK
-    }
-}
diff --git a/lib/pbio/drv/clock/clock_ev3.c b/lib/pbio/drv/clock/clock_ev3.c
index 75dd19883..5ee800a23 100644
--- a/lib/pbio/drv/clock/clock_ev3.c
+++ b/lib/pbio/drv/clock/clock_ev3.c
@@ -1,10 +1,7 @@
-// SPDX-License-Identifier: MPL-1.0
+// SPDX-License-Identifier: MPL-1.0 AND MIT
 // Copyright (c) 2016 Tobias Schießl
-
-// SPDX-License-Identifier: MIT
 // Copyright (c) 2024 The Pybricks Authors
 
-
 #include <pbdrv/config.h>
 
 #if PBDRV_CONFIG_CLOCK_TIAM1808
@@ -35,7 +32,7 @@ static const uint32_t timer_us_division = auxclk_freq_hz / 1000000;
 /**
  * The current tick in milliseconds
  */
-volatile uint32_t systick_ms = 0;
+volatile uint32_t pbdrv_clock_ticks;
 
 /**
  * The systick interrupt service routine (ISR) which will be called every millisecond.
@@ -45,7 +42,7 @@ void systick_isr_C(void) {
     IntSystemStatusClear(SYS_INT_TINT12_0);
     TimerIntStatusClear(SOC_TMR_0_REGS, TMR_INTSTAT12_TIMER_NON_CAPT);
 
-    ++systick_ms;
+    pbdrv_clock_ticks++;
 
     etimer_request_poll();
     pbio_os_request_poll();
@@ -88,7 +85,7 @@ uint32_t pbdrv_clock_get_us(void) {
 }
 
 uint32_t pbdrv_clock_get_ms(void) {
-    return systick_ms;
+    return pbdrv_clock_ticks;
 }
 
 uint32_t pbdrv_clock_get_100us(void) {