diff --git a/watch-library/shared/driver/lis2dw.c b/watch-library/shared/driver/lis2dw.c
index e7ccf2d2..b716f790 100644
--- a/watch-library/shared/driver/lis2dw.c
+++ b/watch-library/shared/driver/lis2dw.c
@@ -26,6 +26,7 @@
 #include "watch.h"
 
 bool lis2dw_begin(void) {
+#ifdef I2C_SERCOM
     if (lis2dw_get_device_id() != LIS2DW_WHO_AM_I_VAL) {
         return false;
     }
@@ -45,21 +46,33 @@ bool lis2dw_begin(void) {
     //  * FIFO disabled
 
     return true;
+#else
+    return false;
+#endif
 }
 
 uint8_t lis2dw_get_device_id(void) {
+#ifdef I2C_SERCOM
     return watch_i2c_read8(LIS2DW_ADDRESS, LIS2DW_REG_WHO_AM_I);
+#else
+    return 0;
+#endif
 }
 
 bool lis2dw_have_new_data(void) {
+#ifdef I2C_SERCOM
     uint8_t retval = watch_i2c_read8(LIS2DW_ADDRESS, LIS2DW_REG_STATUS);
     return retval & LIS2DW_STATUS_VAL_DRDY;
+#else
+    return false;
+#endif
 }
 
 lis2dw_reading_t lis2dw_get_raw_reading(void) {
+    lis2dw_reading_t retval = {0};
+#ifdef I2C_SERCOM
     uint8_t buffer[6];
     uint8_t reg = LIS2DW_REG_OUT_X_L | 0x80; // set high bit for consecutive reads
-    lis2dw_reading_t retval;
 
     watch_i2c_send(LIS2DW_ADDRESS, &reg, 1);
     watch_i2c_receive(LIS2DW_ADDRESS, (uint8_t *)&buffer, 6);
@@ -70,11 +83,15 @@ lis2dw_reading_t lis2dw_get_raw_reading(void) {
     retval.y |= ((uint16_t)buffer[3]) << 8;
     retval.z = buffer[4];
     retval.z |= ((uint16_t)buffer[5]) << 8;
-
+#endif
+    
     return retval;
 }
 
- lis2dw_acceleration_measurement_t lis2dw_get_acceleration_measurement(lis2dw_reading_t *out_reading) {
+lis2dw_acceleration_measurement_t lis2dw_get_acceleration_measurement(lis2dw_reading_t *out_reading) {
+    lis2dw_acceleration_measurement_t retval = {0};
+
+    #ifdef I2C_SERCOM
     lis2dw_reading_t reading = lis2dw_get_raw_reading();
     /// FIXME: We should stash the range in a static variable to avoid reading this every time, but
     /// I'm not sure the values cribbed from Adafruit's LID3DH driver are right for the LIS2DW.
@@ -93,109 +110,175 @@ lis2dw_reading_t lis2dw_get_raw_reading(void) {
     if (range == LIS2DW_RANGE_8_G) lsb_value = 16;
     if (range == LIS2DW_RANGE_16_G) lsb_value = 48;
 
-    lis2dw_acceleration_measurement_t retval;
-
     retval.x = lsb_value * ((float)reading.x / 64000.0);
     retval.y = lsb_value * ((float)reading.y / 64000.0);
     retval.z = lsb_value * ((float)reading.z / 64000.0);
+#else
+    (void) out_reading;
+#endif
 
     return retval;
 }
 
 uint16_t lis2dw_get_temperature(void) {
+#ifdef I2C_SERCOM
     return watch_i2c_read16(LIS2DW_ADDRESS, LIS2DW_REG_OUT_TEMP_L);
+#else
+    return 0;
+#endif
 }
 
 void lis2dw_set_data_rate(lis2dw_data_rate_t dataRate) {
+#ifdef I2C_SERCOM
     uint8_t val = watch_i2c_read8(LIS2DW_ADDRESS, LIS2DW_REG_CTRL1) & ~(0b1111 << 4);
     uint8_t bits = dataRate << 4;
 
     watch_i2c_write8(LIS2DW_ADDRESS, LIS2DW_REG_CTRL1, val | bits);
+#else
+    (void)dataRate;
+#endif
 }
 
 lis2dw_data_rate_t lis2dw_get_data_rate(void) {
+#ifdef I2C_SERCOM
     return watch_i2c_read8(LIS2DW_ADDRESS, LIS2DW_REG_CTRL1) >> 4;
+#else
+    return 0;
+#endif
 }
 
 void lis2dw_set_mode(lis2dw_mode_t mode) {
+#ifdef I2C_SERCOM
     uint8_t val = watch_i2c_read8(LIS2DW_ADDRESS, LIS2DW_REG_CTRL1) & ~(0b1100);
     uint8_t bits = (mode << 2) & 0b1100;
 
     watch_i2c_write8(LIS2DW_ADDRESS, LIS2DW_REG_CTRL1, val | bits);
+#else
+    (void)mode;
+#endif
 }
 
 lis2dw_mode_t lis2dw_get_mode(void) {
+#ifdef I2C_SERCOM
     return (lis2dw_mode_t)(watch_i2c_read8(LIS2DW_ADDRESS, LIS2DW_REG_CTRL1) & 0b1100) >> 2;
+#else
+    return 0;
+#endif
 }
 
 void lis2dw_set_low_power_mode(lis2dw_low_power_mode_t mode) {
+#ifdef I2C_SERCOM
     uint8_t val = watch_i2c_read8(LIS2DW_ADDRESS, LIS2DW_REG_CTRL1) & ~(0b11);
     uint8_t bits = mode & 0b11;
 
     watch_i2c_write8(LIS2DW_ADDRESS, LIS2DW_REG_CTRL1, val | bits);
+#else
+    (void)mode;
+#endif
 }
 
 lis2dw_low_power_mode_t lis2dw_get_low_power_mode(void) {
+#ifdef I2C_SERCOM
     return watch_i2c_read8(LIS2DW_ADDRESS, LIS2DW_REG_CTRL1) & 0b11;
+#else
+    return 0;
+#endif
 }
 
 void lis2dw_set_bandwidth_filtering(lis2dw_bandwidth_filtering_mode_t bwfilter) {
+#ifdef I2C_SERCOM
     uint8_t val = watch_i2c_read8(LIS2DW_ADDRESS, LIS2DW_REG_CTRL6) & ~(LIS2DW_CTRL6_VAL_BANDWIDTH_DIV20);
     uint8_t bits = bwfilter << 6;
     watch_i2c_write8(LIS2DW_ADDRESS, LIS2DW_REG_CTRL6, val | bits);
+#else
+    (void)bwfilter;
+#endif
 }
 
 lis2dw_bandwidth_filtering_mode_t lis2dw_get_bandwidth_filtering(void) {
+#ifdef I2C_SERCOM
     uint8_t retval = watch_i2c_read8(LIS2DW_ADDRESS, LIS2DW_REG_CTRL6) & (LIS2DW_CTRL6_VAL_BANDWIDTH_DIV20);
     retval >>= 6;
     return (lis2dw_bandwidth_filtering_mode_t)retval;
+#else
+    return 0;
+#endif
 }
 
 void lis2dw_set_range(lis2dw_range_t range) {
+#ifdef I2C_SERCOM
     uint8_t val = watch_i2c_read8(LIS2DW_ADDRESS, LIS2DW_REG_CTRL6) & ~(LIS2DW_RANGE_16_G << 4);
     uint8_t bits = range << 4;
 
     watch_i2c_write8(LIS2DW_ADDRESS, LIS2DW_REG_CTRL6, val | bits);
+#else
+    (void)range;
+#endif
 }
 
 lis2dw_range_t lis2dw_get_range(void) {
+#ifdef I2C_SERCOM
     uint8_t retval = watch_i2c_read8(LIS2DW_ADDRESS, LIS2DW_REG_CTRL6) & (LIS2DW_RANGE_16_G << 4);
     retval >>= 4;
     return (lis2dw_range_t)retval;
+#else
+    return 0;
+#endif
 }
 
 void lis2dw_set_filter_type(lis2dw_filter_t bwfilter) {
+#ifdef I2C_SERCOM
     uint8_t val = watch_i2c_read8(LIS2DW_ADDRESS, LIS2DW_REG_CTRL6) & ~(LIS2DW_CTRL6_VAL_FDS_HIGH);
     uint8_t bits = bwfilter << 3;
     watch_i2c_write8(LIS2DW_ADDRESS, LIS2DW_REG_CTRL6, val | bits);
+#else
+    (void)bwfilter;
+#endif
 }
 
 lis2dw_filter_t lis2dw_get_filter_type(void) {
+#ifdef I2C_SERCOM
     uint8_t retval = watch_i2c_read8(LIS2DW_ADDRESS, LIS2DW_REG_CTRL6) & (LIS2DW_CTRL6_VAL_FDS_HIGH);
     retval >>= 3;
     return (lis2dw_filter_t)retval;
+#else
+    return 0;
+#endif
 }
 
 void lis2dw_set_low_noise_mode(bool on) {
+#ifdef I2C_SERCOM
     uint8_t val = watch_i2c_read8(LIS2DW_ADDRESS, LIS2DW_REG_CTRL6) & ~(LIS2DW_CTRL6_VAL_LOW_NOISE);
     uint8_t bits = on ? LIS2DW_CTRL6_VAL_LOW_NOISE : 0;
 
     watch_i2c_write8(LIS2DW_ADDRESS, LIS2DW_REG_CTRL6, val | bits);
+#else
+    (void)on;
+#endif
 }
 
 bool lis2dw_get_low_noise_mode(void) {
+#ifdef I2C_SERCOM
     return (watch_i2c_read8(LIS2DW_ADDRESS, LIS2DW_REG_CTRL1) & LIS2DW_CTRL6_VAL_LOW_NOISE) != 0;
+#else
+    return false;
+#endif
 }
 
 inline void lis2dw_enable_fifo(void) {
+#ifdef I2C_SERCOM
     watch_i2c_write8(LIS2DW_ADDRESS, LIS2DW_REG_FIFO_CTRL, LIS2DW_FIFO_CTRL_MODE_COLLECT_AND_STOP | LIS2DW_FIFO_CTRL_FTH);
+#endif
 }
 
 inline void lis2dw_disable_fifo(void) {
+#ifdef I2C_SERCOM
     watch_i2c_write8(LIS2DW_ADDRESS, LIS2DW_REG_FIFO_CTRL, LIS2DW_FIFO_CTRL_MODE_OFF);
+#endif
 }
 
 bool lis2dw_read_fifo(lis2dw_fifo_t *fifo_data) {
+#ifdef I2C_SERCOM
     uint8_t temp = watch_i2c_read8(LIS2DW_ADDRESS, LIS2DW_REG_FIFO_SAMPLE);
     bool overrun = !!(temp & LIS2DW_FIFO_SAMPLE_OVERRUN);
 
@@ -206,44 +289,67 @@ bool lis2dw_read_fifo(lis2dw_fifo_t *fifo_data) {
     }
 
     return overrun;
+#else
+    (void) fifo_data;
+    return false;
+#endif
 }
 
 void lis2dw_clear_fifo(void) {
+#ifdef I2C_SERCOM
     watch_i2c_write8(LIS2DW_ADDRESS, LIS2DW_REG_FIFO_CTRL, LIS2DW_FIFO_CTRL_MODE_OFF);
     watch_i2c_write8(LIS2DW_ADDRESS, LIS2DW_REG_FIFO_CTRL, LIS2DW_FIFO_CTRL_MODE_COLLECT_AND_STOP | LIS2DW_FIFO_CTRL_FTH);
+#endif
 }
 
 void lis2dw_enable_sleep(void) {
+#ifdef I2C_SERCOM
     uint8_t configuration = watch_i2c_read8(LIS2DW_ADDRESS, LIS2DW_REG_WAKE_UP_THS);
     watch_i2c_write8(LIS2DW_ADDRESS, LIS2DW_REG_WAKE_UP_THS, configuration | LIS2DW_WAKE_UP_THS_VAL_SLEEP_ON);
+#endif
 }
 
 void lis2dw_disable_sleep(void) {
+#ifdef I2C_SERCOM
     uint8_t configuration = watch_i2c_read8(LIS2DW_ADDRESS, LIS2DW_REG_WAKE_UP_THS);
     watch_i2c_write8(LIS2DW_ADDRESS, LIS2DW_REG_WAKE_UP_THS, configuration & ~LIS2DW_WAKE_UP_THS_VAL_SLEEP_ON);
+#endif
 }
 
 void lis2dw_enable_stationary_motion_detection(void) {
+#ifdef I2C_SERCOM
     uint8_t configuration = watch_i2c_read8(LIS2DW_ADDRESS, LIS2DW_REG_WAKE_UP_DUR);
     watch_i2c_write8(LIS2DW_ADDRESS, LIS2DW_REG_WAKE_UP_DUR, configuration | LIS2DW_WAKE_UP_DUR_STATIONARY);
+#endif
 }
 
 void lis2dw_disable_stationary_motion_detection(void) {
+#ifdef I2C_SERCOM
     uint8_t configuration = watch_i2c_read8(LIS2DW_ADDRESS, LIS2DW_REG_WAKE_UP_DUR);
     watch_i2c_write8(LIS2DW_ADDRESS, LIS2DW_REG_WAKE_UP_DUR, configuration & ~LIS2DW_WAKE_UP_DUR_STATIONARY);
+#endif
 }
 
 void lis2dw_configure_wakeup_threshold(uint8_t threshold) {
+#ifdef I2C_SERCOM
     uint8_t configuration = watch_i2c_read8(LIS2DW_ADDRESS, LIS2DW_REG_WAKE_UP_THS) & 0b11000000;
     watch_i2c_write8(LIS2DW_ADDRESS, LIS2DW_REG_WAKE_UP_THS, configuration | threshold);
+#else
+    (void)threshold;
+#endif
 }
 
 void lis2dw_configure_6d_threshold(uint8_t threshold) {
+#ifdef I2C_SERCOM
     uint8_t configuration = watch_i2c_read8(LIS2DW_ADDRESS, LIS2DW_REG_TAP_THS_X) & 0b01100000;
     watch_i2c_write8(LIS2DW_ADDRESS, LIS2DW_REG_TAP_THS_X, configuration | ((threshold & 0b11) << 5));
+#else
+    (void)threshold;
+#endif
 }
 
 void lis2dw_configure_tap_threshold(uint8_t threshold_x, uint8_t threshold_y, uint8_t threshold_z, uint8_t axes_to_enable) {
+#ifdef I2C_SERCOM
     (void) threshold_x;
     (void) threshold_y;
     uint8_t configuration;
@@ -256,39 +362,75 @@ void lis2dw_configure_tap_threshold(uint8_t threshold_x, uint8_t threshold_y, ui
         configuration |= (threshold_z & 0b00011111);
     }
     watch_i2c_write8(LIS2DW_ADDRESS, LIS2DW_REG_TAP_THS_Z, configuration);
+#else
+    (void)threshold_x;
+    (void)threshold_y;
+    (void)threshold_z;
+    (void)axes_to_enable;
+#endif
 }
 
 void lis2dw_configure_tap_duration(uint8_t latency, uint8_t quiet, uint8_t shock) {
+#ifdef I2C_SERCOM
     uint8_t configuration = (latency << 4) | ((quiet & 0b11) << 2) | (shock & 0b11);
     watch_i2c_write8(LIS2DW_ADDRESS, LIS2DW_REG_INT1_DUR, configuration);
+#else
+    (void)latency;
+    (void)quiet;
+    (void)shock;
+#endif
 }
 
 void lis2dw_configure_int1(uint8_t sources) {
+#ifdef I2C_SERCOM
     watch_i2c_write8(LIS2DW_ADDRESS, LIS2DW_REG_CTRL4_INT1, sources);
+#else
+    (void)sources;
+#endif
 }
 
 void lis2dw_configure_int2(uint8_t sources) {
+#ifdef I2C_SERCOM
     watch_i2c_write8(LIS2DW_ADDRESS, LIS2DW_REG_CTRL5_INT2, sources);
+#else
+    (void)sources;
+#endif
 }
 
 void lis2dw_enable_interrupts(void) {
+#ifdef I2C_SERCOM
     uint8_t configuration = watch_i2c_read8(LIS2DW_ADDRESS, LIS2DW_REG_CTRL7);
     watch_i2c_write8(LIS2DW_ADDRESS, LIS2DW_REG_CTRL7, configuration | LIS2DW_CTRL7_VAL_INTERRUPTS_ENABLE);
+#endif
 }
 
 void lis2dw_disable_interrupts(void) {
+#ifdef I2C_SERCOM
     uint8_t configuration = watch_i2c_read8(LIS2DW_ADDRESS, LIS2DW_REG_CTRL7);
     watch_i2c_write8(LIS2DW_ADDRESS, LIS2DW_REG_CTRL7, configuration & ~LIS2DW_CTRL7_VAL_INTERRUPTS_ENABLE);
+#endif
 }
 
 lis2dw_wakeup_source_t lis2dw_get_wakeup_source() {
+#ifdef I2C_SERCOM
     return (lis2dw_wakeup_source_t) watch_i2c_read8(LIS2DW_ADDRESS, LIS2DW_REG_WAKE_UP_SRC);
+#else
+    return 0;
+#endif
 }
 
 lis2dw_interrupt_source_t lis2dw_get_interrupt_source(void) {
+#ifdef I2C_SERCOM
     return (lis2dw_interrupt_source_t) watch_i2c_read8(LIS2DW_ADDRESS, LIS2DW_REG_ALL_INT_SRC);
+#else
+    return 0;
+#endif
 }
 
 uint8_t lis2dw_get_wakeup_threshold(void) {
+#ifdef I2C_SERCOM
     return watch_i2c_read8(LIS2DW_ADDRESS, LIS2DW_REG_WAKE_UP_THS) & 0b00111111;
+#else
+    return 0;
+#endif
 }