diff --git a/ports/atmel-samd/common-hal/microcontroller/__init__.c b/ports/atmel-samd/common-hal/microcontroller/__init__.c
index 751f4dcab7..983af7a647 100644
--- a/ports/atmel-samd/common-hal/microcontroller/__init__.c
+++ b/ports/atmel-samd/common-hal/microcontroller/__init__.c
@@ -103,6 +103,17 @@ const nvm_bytearray_obj_t common_hal_mcu_nvm_obj = {
 };
 #endif
 
+#if CIRCUITPY_WATCHDOG
+// The singleton watchdog.WatchDogTimer object.
+watchdog_watchdogtimer_obj_t common_hal_mcu_watchdogtimer_obj = {
+    .base = {
+        .type = &watchdog_watchdogtimer_type,
+    },
+    .timeout = 0.0f,
+    .mode = WATCHDOGMODE_NONE,
+};
+#endif
+
 // This maps MCU pin names to pin objects.
 STATIC const mp_rom_map_elem_t mcu_pin_global_dict_table[] = {
     #if defined(PIN_PA00) && !defined(IGNORE_PIN_PA00)
diff --git a/ports/atmel-samd/common-hal/watchdog/WatchDogMode.c b/ports/atmel-samd/common-hal/watchdog/WatchDogMode.c
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/ports/atmel-samd/common-hal/watchdog/WatchDogTimer.c b/ports/atmel-samd/common-hal/watchdog/WatchDogTimer.c
new file mode 100644
index 0000000000..29ac643d1c
--- /dev/null
+++ b/ports/atmel-samd/common-hal/watchdog/WatchDogTimer.c
@@ -0,0 +1,105 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2021 Jeff Epler for Adafruit Industries
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <math.h>
+
+#include "py/runtime.h"
+
+#include "shared-bindings/watchdog/__init__.h"
+#include "shared-bindings/watchdog/WatchDogTimer.h"
+#include "common-hal/watchdog/WatchDogTimer.h"
+
+#include "component/wdt.h"
+
+void common_hal_watchdog_feed(watchdog_watchdogtimer_obj_t *self) {
+    WDT->CLEAR.reg = WDT_CLEAR_CLEAR_KEY;
+}
+
+void common_hal_watchdog_deinit(watchdog_watchdogtimer_obj_t *self) {
+    if (self->mode == WATCHDOGMODE_RESET) {
+        mp_raise_RuntimeError(translate("WatchDogTimer cannot be deinitialized once mode is set to RESET"));
+    } else {
+        self->mode = WATCHDOGMODE_NONE;
+    }
+}
+
+mp_float_t common_hal_watchdog_get_timeout(watchdog_watchdogtimer_obj_t *self) {
+    return self->timeout;
+}
+
+void setup_wdt(watchdog_watchdogtimer_obj_t *self, int setting) {
+    OSC32KCTRL->OSCULP32K.bit.EN1K = 1;  // Enable out 1K (for WDT)
+
+    // disable watchdog for config
+    WDT->CTRLA.reg = 0;
+    while (WDT->SYNCBUSY.reg) { // Sync CTRL write
+    }
+
+    WDT->INTENCLR.bit.EW = 1;   // Disable early warning interrupt
+    WDT->CONFIG.bit.PER = setting; // Set period for chip reset
+    WDT->CTRLA.bit.WEN = 0;     // Disable window mode
+    while (WDT->SYNCBUSY.reg) { // Sync CTRL write
+    }
+    common_hal_watchdog_feed(self); // Clear watchdog interval
+    WDT->CTRLA.bit.ENABLE = 1; // Start watchdog now!
+    while (WDT->SYNCBUSY.reg) {
+    }
+}
+
+void common_hal_watchdog_set_timeout(watchdog_watchdogtimer_obj_t *self, mp_float_t new_timeout) {
+    int wdt_cycles = (int)(new_timeout * 1000);
+    if (wdt_cycles < 8) {
+        wdt_cycles = 8;
+    }
+    if (wdt_cycles > 16384) {
+        mp_raise_ValueError(translate("timeout duration exceeded the maximum supported value"));
+    }
+    // ceil(log2(n)) = 32 - __builtin_clz(n - 1) when n > 1 (if int is 32 bits)
+    int log2_wdt_cycles = (sizeof(int) * CHAR_BIT) - __builtin_clz(wdt_cycles - 1);
+    int setting = log2_wdt_cycles - 3; // CYC8_Val is 0
+    float timeout = (8 << setting) / 1024.f;
+
+    if (self->mode == WATCHDOGMODE_RESET) {
+        setup_wdt(self, setting);
+    }
+    self->timeout = timeout;
+}
+
+watchdog_watchdogmode_t common_hal_watchdog_get_mode(watchdog_watchdogtimer_obj_t *self) {
+    return self->mode;
+}
+
+void common_hal_watchdog_set_mode(watchdog_watchdogtimer_obj_t *self, watchdog_watchdogmode_t new_mode) {
+    if (self->mode != new_mode) {
+        if (new_mode == WATCHDOGMODE_RAISE) {
+            mp_raise_NotImplementedError(translate("RAISE mode is not implemented"));
+        } else if (new_mode == WATCHDOGMODE_NONE) {
+            common_hal_watchdog_deinit(self);
+        }
+        self->mode = new_mode;
+        common_hal_watchdog_set_timeout(self, self->timeout);
+    }
+}
diff --git a/ports/atmel-samd/common-hal/watchdog/WatchDogTimer.h b/ports/atmel-samd/common-hal/watchdog/WatchDogTimer.h
new file mode 100644
index 0000000000..ce34f0b8ab
--- /dev/null
+++ b/ports/atmel-samd/common-hal/watchdog/WatchDogTimer.h
@@ -0,0 +1,43 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2020 microDev
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef MICROPY_INCLUDED_RASPBERRYPI_COMMON_HAL_WATCHDOG_WATCHDOGTIMER_H
+#define MICROPY_INCLUDED_RASPBERRYPI_COMMON_HAL_WATCHDOG_WATCHDOGTIMER_H
+
+#include "py/obj.h"
+#include "shared-bindings/watchdog/WatchDogMode.h"
+#include "shared-bindings/watchdog/WatchDogTimer.h"
+
+struct _watchdog_watchdogtimer_obj_t {
+    mp_obj_base_t base;
+    mp_float_t timeout;
+    watchdog_watchdogmode_t mode;
+};
+
+// This needs to be called in order to disable the watchdog
+// void watchdog_reset(void);
+
+#endif // MICROPY_INCLUDED_RASPBERRYPI_COMMON_HAL_WATCHDOG_WATCHDOGTIMER_H
diff --git a/ports/atmel-samd/common-hal/watchdog/__init__.c b/ports/atmel-samd/common-hal/watchdog/__init__.c
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/ports/atmel-samd/mpconfigport.mk b/ports/atmel-samd/mpconfigport.mk
index 8994f0f52a..4a5c7a41d6 100644
--- a/ports/atmel-samd/mpconfigport.mk
+++ b/ports/atmel-samd/mpconfigport.mk
@@ -102,6 +102,7 @@ CIRCUITPY_PS2IO ?= 1
 CIRCUITPY_SAMD ?= 1
 CIRCUITPY_RGBMATRIX ?= $(CIRCUITPY_FULL_BUILD)
 CIRCUITPY_FRAMEBUFFERIO ?= $(CIRCUITPY_FULL_BUILD)
+CIRCUITPY_WATCHDOG ?= 1
 
 endif # samd51
 ######################################################################
diff --git a/py/objstr.c b/py/objstr.c
index 06396314cb..3d45383bb3 100644
--- a/py/objstr.c
+++ b/py/objstr.c
@@ -1556,7 +1556,7 @@ STATIC mp_obj_t str_modulo_format(mp_obj_t pattern, size_t n_args, const mp_obj_
                     char ch = mp_obj_get_int(arg);
                     mp_print_strn(&print, &ch, 1, flags, ' ', width);
                 } else {
-                    mp_raise_TypeError(MP_ERROR_TEXT("integer required"));
+                    mp_raise_TypeError(MP_ERROR_TEXT("%%c requires int or char"));
                 }
                 break;
 
diff --git a/shared-bindings/watchdog/__init__.h b/shared-bindings/watchdog/__init__.h
index b5a0ad71d1..0921141129 100644
--- a/shared-bindings/watchdog/__init__.h
+++ b/shared-bindings/watchdog/__init__.h
@@ -27,6 +27,9 @@
 #ifndef MICROPY_INCLUDED_SHARED_BINDINGS_WATCHDOG___INIT___H
 #define MICROPY_INCLUDED_SHARED_BINDINGS_WATCHDOG___INIT___H
 
+#include "py/obj.h"
+#include "py/objexcept.h"
+
 extern const mp_obj_module_t watchdog_module;
 extern mp_obj_exception_t mp_watchdog_timeout_exception;
 extern const mp_obj_type_t mp_type_WatchDogTimeout;