lis2dw: add FIFO support

3 files changed, 78 insertions, 22 deletions

diff --git a/apps/accelerometer-test/app.c b/apps/accelerometer-test/app.c
index 1f7803c6..1a3acafa 100644
--- a/apps/accelerometer-test/app.c
+++ b/apps/accelerometer-test/app.c
@@ -24,17 +24,13 @@ static void cb_tick(void) {
     if (!lis2dw_have_new_data()) return;
 
     watch_set_indicator(WATCH_INDICATOR_SIGNAL);
-    lis2dw_reading raw_reading;
-    lis2dw_acceleration_measurement measurement = lis2dw_get_acceleration_measurement(&raw_reading);
-    printf("%f, %f, %f\n", measurement.x, measurement.y, measurement.z);
-    char buf[128];
-    sprintf(buf, "%f, %f, %f\n", measurement.x, measurement.y, measurement.z);
-    watch_debug_puts(buf);
+    lis2dw_fifo_t fifo;
+    bool overrun = lis2dw_read_fifo(&fifo);
+    printf("FIFO captured %d readings.\n", fifo.count);
+    if (overrun) printf("\tThere was an overrun!\n\n");
 }
 
 void app_init(void) {
-    watch_enable_debug_uart(460800); // this is glitchy now, but this enables a baud rate of 115200 when USB is disabled.
-
     watch_enable_display();
     watch_display_string("AC  Strean", 0);
 
@@ -45,12 +41,14 @@ void app_init(void) {
 
     watch_enable_i2c();
     lis2dw_begin();
-    lis2dw_set_data_rate(LIS2DW_DATA_RATE_25_HZ); // is this enough for training?
-    lis2dw_set_low_noise_mode(true); // consumes a little more power
     lis2dw_set_low_power_mode(LIS2DW_LP_MODE_2); // lowest power 14-bit mode, 25 Hz is 3.5 µA @ 1.8V w/ low noise, 3µA without
+    lis2dw_set_low_noise_mode(true); // consumes a little more power
     lis2dw_set_range(LIS2DW_CTRL6_VAL_RANGE_4G);
+    lis2dw_set_data_rate(LIS2DW_DATA_RATE_25_HZ); // is this enough for training?
+
+    lis2dw_enable_fifo();
 
-    watch_rtc_register_periodic_callback(cb_tick, 64);
+    watch_rtc_register_periodic_callback(cb_tick, 1);
 }
 
 void app_wake_from_backup(void) {
diff --git a/watch-library/shared/driver/lis2dw.c b/watch-library/shared/driver/lis2dw.c
index 6e1ac56d..fce266b3 100644
--- a/watch-library/shared/driver/lis2dw.c
+++ b/watch-library/shared/driver/lis2dw.c
@@ -50,10 +50,10 @@ bool lis2dw_have_new_data(void) {
     return retval & LIS2DW_STATUS_VAL_DRDY;
 }
 
-lis2dw_reading lis2dw_get_raw_reading(void) {
+lis2dw_reading_t lis2dw_get_raw_reading(void) {
     uint8_t buffer[6];
     uint8_t reg = LIS2DW_REG_OUT_X_L | 0x80; // set high bit for consecutive reads
-    lis2dw_reading retval;
+    lis2dw_reading_t retval;
 
     watch_i2c_send(LIS2DW_ADDRESS, &reg, 1);
     watch_i2c_receive(LIS2DW_ADDRESS, (uint8_t *)&buffer, 6);
@@ -68,8 +68,8 @@ lis2dw_reading lis2dw_get_raw_reading(void) {
     return retval;
 }
 
- lis2dw_acceleration_measurement lis2dw_get_acceleration_measurement(lis2dw_reading *out_reading) {
-    lis2dw_reading reading = lis2dw_get_raw_reading();
+ lis2dw_acceleration_measurement_t lis2dw_get_acceleration_measurement(lis2dw_reading_t *out_reading) {
+    lis2dw_reading_t reading = lis2dw_get_raw_reading();
     uint8_t range = lis2dw_get_range();
     if (out_reading != NULL) *out_reading = reading;
 
@@ -82,7 +82,7 @@ lis2dw_reading 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 retval;
+    lis2dw_acceleration_measurement_t retval;
 
     retval.x = lsb_value * ((float)reading.x / 64000.0);
     retval.y = lsb_value * ((float)reading.y / 64000.0);
@@ -104,7 +104,6 @@ lis2dw_range_t lis2dw_get_range(void) {
     return (lis2dw_range_t)retval;
 }
 
-
 void lis2dw_set_data_rate(lis2dw_data_rate_t dataRate) {
     uint8_t val = watch_i2c_read8(LIS2DW_ADDRESS, LIS2DW_REG_CTRL1) & ~(0b1111 << 4);
     uint8_t bits = dataRate << 4;
@@ -137,3 +136,31 @@ void lis2dw_set_low_noise_mode(bool on) {
 bool lis2dw_get_low_noise_mode(void) {
     return (watch_i2c_read8(LIS2DW_ADDRESS, LIS2DW_REG_CTRL1) & LIS2DW_CTRL6_VAL_LOW_NOISE) != 0;
 }
+
+inline void lis2dw_disable_fifo(void) {
+    watch_i2c_write8(LIS2DW_ADDRESS, LIS2DW_REG_FIFO_CTRL, LIS2DW_FIFO_CTRL_MODE_OFF);
+}
+
+inline void lis2dw_enable_fifo(void) {
+    watch_i2c_write8(LIS2DW_ADDRESS, LIS2DW_REG_FIFO_CTRL, LIS2DW_FIFO_CTRL_MODE_COLLECT_AND_STOP | LIS2DW_FIFO_CTRL_FTH);
+}
+
+bool lis2dw_read_fifo(lis2dw_fifo_t *fifo_data) {
+    uint8_t temp = watch_i2c_read8(LIS2DW_ADDRESS, LIS2DW_REG_FIFO_SAMPLE);
+    bool overrun = !!(temp & LIS2DW_FIFO_SAMPLE_OVERRUN);
+    uint8_t buffer[6];
+
+    fifo_data->count = temp & LIS2DW_FIFO_SAMPLE_COUNT;
+
+    for(int i = 0; i < fifo_data->count; i++) {
+        watch_i2c_receive(LIS2DW_ADDRESS, (uint8_t *)&buffer, 6);
+        fifo_data->readings[i] = lis2dw_get_raw_reading();
+    }
+
+    return overrun;
+}
+
+void lis2dw_clear_fifo(void) {
+    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);
+}
diff --git a/watch-library/shared/driver/lis2dw.h b/watch-library/shared/driver/lis2dw.h
index 22b4484f..41611172 100644
--- a/watch-library/shared/driver/lis2dw.h
+++ b/watch-library/shared/driver/lis2dw.h
@@ -32,13 +32,18 @@ typedef struct {
     int16_t x;
     int16_t y;
     int16_t z;
-} lis2dw_reading;
+} lis2dw_reading_t;
 
 typedef struct {
     float x;
     float y;
     float z;
-} lis2dw_acceleration_measurement;
+} lis2dw_acceleration_measurement_t;
+
+typedef struct {
+    int8_t count;
+    lis2dw_reading_t readings[32];
+} lis2dw_fifo_t;
 
 typedef enum {
   LIS2DW_DATA_RATE_POWERDOWN = 0,
@@ -61,6 +66,14 @@ typedef enum {
 } lis2dw_mode_t;
 
 typedef enum {
+  LIS2DW_FIFO_MODE_OFF = 0b000,
+  LIS2DW_FIFO_MODE_COLLECT_AND_STOP = 0b001,
+  LIS2DW_FIFO_MODE_CONTINUOUS_TO_FIFO = 0b011,
+  LIS2DW_FIFO_MODE_BYPASS_TO_CONTINUOUS = 0b100,
+  LIS2DW_FIFO_MODE_COLLECT_CONTINUOUS = 0b110,
+} lis2dw_fifo_mode_t;
+
+typedef enum {
   LIS2DW_LP_MODE_1 = 0b00, // 12-bit
   LIS2DW_LP_MODE_2 = 0b01, // 14-bit
   LIS2DW_LP_MODE_3 = 0b10, // 14-bit
@@ -177,7 +190,17 @@ typedef enum {
 #define LIS2DW_REG_OUT_Z_H 0x2D
 
 #define LIS2DW_REG_FIFO_CTRL 0x2E
-#define LIS2DW_REG_FIFO_SRC 0x2F
+#define LIS2DW_FIFO_CTRL_MODE_OFF                   (LIS2DW_FIFO_MODE_OFF << 5)
+#define LIS2DW_FIFO_CTRL_MODE_COLLECT_AND_STOP      (LIS2DW_FIFO_MODE_COLLECT_AND_STOP << 5)
+#define LIS2DW_FIFO_CTRL_MODE_CONTINUOUS_TO_FIFO    (LIS2DW_FIFO_MODE_CONTINUOUS_TO_FIFO << 5)
+#define LIS2DW_FIFO_CTRL_MODE_BYPASS_TO_CONTINUOUS  (LIS2DW_FIFO_MODE_BYPASS_TO_CONTINUOUS << 5)
+#define LIS2DW_FIFO_CTRL_MODE_COLLECT_CONTINUOUS    (LIS2DW_FIFO_MODE_COLLECT_CONTINUOUS << 5)
+#define LIS2DW_FIFO_CTRL_FTH                        (0b00011111)
+
+#define LIS2DW_REG_FIFO_SAMPLE 0x2F
+#define LIS2DW_FIFO_SAMPLE_THRESHOLD (1 << 7)
+#define LIS2DW_FIFO_SAMPLE_OVERRUN (1 << 6)
+#define LIS2DW_FIFO_SAMPLE_COUNT (0b00111111)
 
 #define LIS2DW_REG_TAP_THS_X 0x30
 #define LIS2DW_REG_TAP_THS_Y 0x31
@@ -242,9 +265,9 @@ uint8_t lis2dw_get_device_id(void);
 
 bool lis2dw_have_new_data(void);
 
-lis2dw_reading lis2dw_get_raw_reading(void);
+lis2dw_reading_t lis2dw_get_raw_reading(void);
 
-lis2dw_acceleration_measurement lis2dw_get_acceleration_measurement(lis2dw_reading *out_reading);
+lis2dw_acceleration_measurement_t lis2dw_get_acceleration_measurement(lis2dw_reading_t *out_reading);
 
 void lis2dw_set_range(lis2dw_range_t range);
 
@@ -262,4 +285,12 @@ void lis2dw_set_low_noise_mode(bool on);
 
 bool lis2dw_get_low_noise_mode(void);
 
+void lis2dw_disable_fifo(void);
+
+void lis2dw_enable_fifo(void);
+
+bool lis2dw_read_fifo(lis2dw_fifo_t *fifo_data);
+
+void lis2dw_clear_fifo(void);
+
 #endif // LIS2DW_H