FIFO example

example/README.md

@@ -12,11 +12,13 @@ The watermark level can be adjusted to a value [1-32] (0 disables FIFO) by modif
 
 The FIFO "engine" samples/appends another set of [x y z] values at 1/ODR. The maximum ODR supported by the FIFO "engine" is 200 Hz.
 
+**files in `fifo/` dir**
+
 | FIFO mode        |  symbol               | description                |
 |------------------|-----------------------|----------------------------|
 |  Bypass          |   `LIS3DH_FIFO_MODE_BYPASS` | FIFO is inoperational      |
-|  FIFO            |   `LIS3DH_FIFO_MODE_FIFO`   | FIFO can be read/emptied at any time but once overrun has to be reset. See file: `fifo-mode-fifo.c`     |
+|  FIFO            |   `LIS3DH_FIFO_MODE_FIFO`   | FIFO can be read/emptied at any time but once overrun has to be reset. See files: `fifo-int-ovrn.c`, `fifo-int-wtm.c`, `fifo.c`     |
-|  Stream          |   `LIS3DH_FIFO_MODE_STREAM` | FIFO continously writes new data at 1/ODR and will overwrite old data until it is read/emptied. See file: `fifo-mode-stream.c`    |
+|  Stream          |   `LIS3DH_FIFO_MODE_STREAM` | FIFO continously writes new data at 1/ODR and will overwrite old data until it is read/emptied. See files: `stream-int-ovrn.c`, `stream-int-wtm.c`, `stream.c`    |
 |  Stream_to_FIFO  |   `LIS3DH_FIFO_STREAM_TO_FIFO`  | FIFO behaves like Stream mode until a set interrupt is activated, then changes to a mode FIFO. |
 
 Note: FIFO will not trigger a watermark interrupt (`pin1.wtm`) if the FIFO size is default (32; maximum size). To use the watermark interrupt, the FIFO size has to be between [1-31]. An overrun interrupt (`pin1.overrun`) will always trigger when the FIFO is full, regardless of programmed capacity.

example/fifo-mode-fifo.c

@@ -1,49 +0,0 @@
-#define _GNU_SOURCE
-#include <unistd.h>
-#include <stdio.h>
-#include "lis3dh.h"
-#include "i2c.h"
-#include "interrupt.h"
-
-#define GPIO_INTERRUPT_PIN_INT1 12
-
-int main() {
-
-    lis3dh_t lis;
-    struct lis3dh_fifo_data fifo;
-    int i;
-
-    lis.dev.init = i2c_init;
-    lis.dev.read = i2c_read;
-    lis.dev.write = i2c_write;
-    lis.dev.sleep = usleep;
-    lis.dev.deinit = i2c_deinit;
-
-    lis3dh_init(&lis);
-    lis3dh_reset(&lis);
-    int_register(GPIO_INTERRUPT_PIN_INT1);
-
-    lis.cfg.mode = LIS3DH_MODE_HR;
-    lis.cfg.range = LIS3DH_FS_2G;
-    lis.cfg.rate = LIS3DH_ODR_100_HZ;
-    lis.cfg.pin1.overrun = 1;
-    lis.cfg.fifo.mode = LIS3DH_FIFO_MODE_FIFO;
-    lis.cfg.fifo.trig = LIS3DH_FIFO_TRIG_INT1;
-
-    lis3dh_configure(&lis);
-
-    for ( ;; ) {
-
-        int_poll(GPIO_INTERRUPT_PIN_INT1);
-        lis3dh_read_fifo(&lis, &fifo);
-        for(i=0; i<fifo.size; i++)
-            printf("x: %4.4d mg, y: %4.4d mg, z: %4.4d mg\n", fifo.x[i], fifo.y[i], fifo.z[i]);
-
-        printf("fifo.size=%d\n", fifo.size);
-        lis3dh_fifo_reset(&lis);
-    }
-
-    lis3dh_deinit(&lis);
-
-    return 0;
-}

example/fifo-mode-stream.c

@@ -1,48 +0,0 @@
-#define _GNU_SOURCE
-#include <unistd.h>
-#include <stdio.h>
-#include "lis3dh.h"
-#include "i2c.h"
-#include "interrupt.h"
-
-#define GPIO_INTERRUPT_PIN_INT1 12
-
-int main() {
-
-    lis3dh_t lis;
-    struct lis3dh_fifo_data fifo;
-    int i;
-
-    lis.dev.init = i2c_init;
-    lis.dev.read = i2c_read;
-    lis.dev.write = i2c_write;
-    lis.dev.sleep = usleep;
-    lis.dev.deinit = i2c_deinit;
-
-    lis3dh_init(&lis);
-    lis3dh_reset(&lis);
-    int_register(GPIO_INTERRUPT_PIN_INT1);
-
-    lis.cfg.mode = LIS3DH_MODE_HR;
-    lis.cfg.range = LIS3DH_FS_2G;
-    lis.cfg.rate = LIS3DH_ODR_100_HZ;
-    lis.cfg.pin1.overrun = 1;
-    lis.cfg.fifo.mode = LIS3DH_FIFO_MODE_STREAM;
-    lis.cfg.fifo.trig = LIS3DH_FIFO_TRIG_INT1;
-
-    lis3dh_configure(&lis);
-
-    for ( ;; ) {
-
-        int_poll(GPIO_INTERRUPT_PIN_INT1);
-        lis3dh_read_fifo(&lis, &fifo);
-        for(i=0; i<fifo.size; i++)
-            printf("x: %4.4d mg, y: %4.4d mg, z: %4.4d mg\n", fifo.x[i], fifo.y[i], fifo.z[i]);
-
-        printf("fifo.size=%d\n", fifo.size);
-    }
-
-    lis3dh_deinit(&lis);
-
-    return 0;
-}

example/fifo/fifo-int-ovrn.c

@@ -0,0 +1,82 @@
+#define _GNU_SOURCE /* usleep() */
+#include <unistd.h> /* usleep() */
+#include <stdio.h>
+#include "lis3dh.h"
+#include "i2c.h"
+#include "interrupt.h"
+
+/* Raspberry Pi GPIO pin connected to LIS3DH INT1 pin */
+#define GPIO_INTERRUPT_PIN_INT1 12
+
+int main() {
+
+    lis3dh_t lis;
+    struct lis3dh_fifo_data fifo;
+    int i;
+
+    lis.dev.init = i2c_init;
+    lis.dev.read = i2c_read;
+    lis.dev.write = i2c_write;
+    lis.dev.sleep = usleep;
+    lis.dev.deinit = i2c_deinit;
+
+    /* initialise struct and check device id */
+    if (lis3dh_init(&lis)) {
+        /* error handling */
+    }
+
+    /* reset just in case*/
+    if (lis3dh_reset(&lis)) {
+        /* error handling */
+    }
+    
+    /* register interrupt */
+    if (int_register(GPIO_INTERRUPT_PIN_INT1)) {
+        /* error handling */
+    }
+
+    lis.cfg.mode = LIS3DH_MODE_HR;
+    lis.cfg.range = LIS3DH_FS_2G;
+    lis.cfg.rate = LIS3DH_ODR_100_HZ;
+    lis.cfg.pin1.overrun = 1;
+    lis.cfg.fifo.mode = LIS3DH_FIFO_MODE_FIFO;
+    lis.cfg.fifo.trig = LIS3DH_FIFO_TRIG_INT1;
+
+    /* write cfg to device */
+    if (lis3dh_configure(&lis)) {
+        /* error handling */
+    }
+
+    for ( ;; ) {
+
+        /* wait until FIFO overrun interrupt is active */
+        if (int_poll(GPIO_INTERRUPT_PIN_INT1)) {
+            /* error handling */
+        }
+
+        /* read FIFO into `fifo_data' struct `fifo' */
+        if (lis3dh_read_fifo(&lis, &fifo)) {
+            /* error handling */
+        }
+
+        /* print data .. */
+        for(i=0; i<fifo.size; i++) {
+            printf("x: %4.4d mg, y: %4.4d mg, z: %4.4d mg\n", fifo.x[i], fifo.y[i], fifo.z[i]);
+        }
+
+        printf("fifo.size=%d\n", fifo.size);
+
+        /* in FIFO mode, the FIFO engine must be restarted after it has been overrun */
+        /* otherwise, it will not fill up again. */
+        if (lis3dh_fifo_reset(&lis)) {
+            /* error handling */
+        }
+    }
+
+    /* deinitalise device */
+    if (lis3dh_deinit(&lis)) {
+        /* error handling */
+    }
+
+    return 0;
+}

example/fifo/fifo-int-wtm.c

@@ -0,0 +1,84 @@
+#define _GNU_SOURCE /* usleep() */
+#include <unistd.h> /* usleep() */
+#include <stdio.h>
+#include "lis3dh.h"
+#include "i2c.h"
+#include "interrupt.h"
+
+/* Raspberry Pi GPIO pin connected to LIS3DH INT1 pin */
+#define GPIO_INTERRUPT_PIN_INT1 12
+
+int main() {
+
+    lis3dh_t lis;
+    struct lis3dh_fifo_data fifo;
+    int i;
+
+    lis.dev.init = i2c_init;
+    lis.dev.read = i2c_read;
+    lis.dev.write = i2c_write;
+    lis.dev.sleep = usleep;
+    lis.dev.deinit = i2c_deinit;
+
+    /* initialise struct and check device id */
+    if (lis3dh_init(&lis)) {
+        /* error handling */
+    }
+
+    /* reset just in case*/
+    if (lis3dh_reset(&lis)) {
+        /* error handling */
+    }
+    
+    /* register interrupt */
+    if (int_register(GPIO_INTERRUPT_PIN_INT1)) {
+        /* error handling */
+    }
+
+    lis.cfg.mode = LIS3DH_MODE_HR;
+    lis.cfg.range = LIS3DH_FS_2G;
+    lis.cfg.rate = LIS3DH_ODR_100_HZ;
+    lis.cfg.pin1.wtm = 1; /* watermark interrupt */
+    lis.cfg.fifo.mode = LIS3DH_FIFO_MODE_FIFO;
+    lis.cfg.fifo.trig = LIS3DH_FIFO_TRIG_INT1;
+    lis.cfg.fifo.size = 15; /* size must be < 32 to use the watermark interrupt */
+
+    /* write cfg to device */
+    if (lis3dh_configure(&lis)) {
+        /* error handling */
+    }
+
+    for ( ;; ) {
+
+        /* wait until FIFO overrun interrupt is active */
+        if (int_poll(GPIO_INTERRUPT_PIN_INT1)) {
+            /* error handling */
+        }
+
+        /* read FIFO into `fifo_data' struct `fifo' */
+        if (lis3dh_read_fifo(&lis, &fifo)) {
+            /* error handling */
+        }
+
+        /* print data .. */
+        for(i=0; i<fifo.size; i++) {
+            printf("x: %4.4d mg, y: %4.4d mg, z: %4.4d mg\n", fifo.x[i], fifo.y[i], fifo.z[i]);
+        }
+
+        printf("fifo.size=%d\n", fifo.size);
+
+        /* Since the WTM is less than the full size, there is no need to reset the device after reading */
+        /* However, if the reading of the device is somehow delayed and the FIFO fills up between */
+        /* receiving the wtm interrupt, and calling lis3dh_read_fifo(), the FIFO must be reset. */
+        /* this can easily be simulated by calling a sleep function. */
+        /* Therefore, it is a good idea to reset the FIFO anyway. */
+        lis3dh_fifo_reset(&lis);
+    }
+
+    /* deinitalise device */
+    if (lis3dh_deinit(&lis)) {
+        /* error handling */
+    }
+
+    return 0;
+}

example/fifo/fifo.c

@@ -0,0 +1,71 @@
+#define _GNU_SOURCE /* usleep() */
+#include <unistd.h> /* usleep() */
+#include <stdio.h>
+#include "lis3dh.h"
+#include "i2c.h"
+
+int main() {
+
+    lis3dh_t lis;
+    struct lis3dh_fifo_data fifo;
+    int i;
+
+    lis.dev.init = i2c_init;
+    lis.dev.read = i2c_read;
+    lis.dev.write = i2c_write;
+    lis.dev.sleep = usleep;
+    lis.dev.deinit = i2c_deinit;
+
+    /* initialise struct and check device id */
+    if (lis3dh_init(&lis)) {
+        /* error handling */
+    }
+
+    /* reset just in case*/
+    if (lis3dh_reset(&lis)) {
+        /* error handling */
+    }
+
+    lis.cfg.mode = LIS3DH_MODE_HR;
+    lis.cfg.range = LIS3DH_FS_2G;
+    lis.cfg.rate = LIS3DH_ODR_100_HZ;
+    lis.cfg.fifo.mode = LIS3DH_FIFO_MODE_FIFO;
+
+    /* modifying the size of the FIFO buffer is not useful when just polling without interrupts */
+
+    /* write cfg to device */
+    if (lis3dh_configure(&lis)) {
+        /* error handling */
+    }
+
+    for ( ;; ) {
+
+        /* read FIFO into `fifo_data' struct `fifo' */
+        if (lis3dh_read_fifo(&lis, &fifo)) {
+            /* error handling */
+        }
+
+        /* print data .. */
+        for(i=0; i<fifo.size; i++) {
+            printf("x: %4.4d mg, y: %4.4d mg, z: %4.4d mg\n", fifo.x[i], fifo.y[i], fifo.z[i]);
+        }
+
+        /* FIFO size will rarely go above 2 in this example, because lis3dh_read_fifo() */
+        /* does not wait for the FIFO buffer to be full, just non-empty. */
+        printf("fifo.size=%d\n", fifo.size);
+
+        /* Since the WTM is less than the full size, there is no need to reset the device after reading */
+        /* However, if the reading of the device is somehow delayed and the FIFO fills up between */
+        /* calls to lis3dh_read_fifo(), then the device is overrun, and must be reset. */
+        /* this can easily be simulated by calling a sleep function. */
+        /* Therefore, it is a good idea to reset the FIFO anyway. */
+        lis3dh_fifo_reset(&lis);
+    }
+
+    /* deinitalise device */
+    if (lis3dh_deinit(&lis)) {
+        /* error handling */
+    }
+
+    return 0;
+}

example/fifo/stream-int-ovrn.c

@@ -0,0 +1,78 @@
+#define _GNU_SOURCE /* usleep() */
+#include <unistd.h> /* usleep() */
+#include <stdio.h>
+#include "lis3dh.h"
+#include "i2c.h"
+#include "interrupt.h"
+
+/* Raspberry Pi GPIO pin connected to LIS3DH INT1 pin */
+#define GPIO_INTERRUPT_PIN_INT1 12
+
+int main() {
+
+    lis3dh_t lis;
+    struct lis3dh_fifo_data fifo;
+    int i;
+
+    lis.dev.init = i2c_init;
+    lis.dev.read = i2c_read;
+    lis.dev.write = i2c_write;
+    lis.dev.sleep = usleep;
+    lis.dev.deinit = i2c_deinit;
+
+    /* initialise struct and check device id */
+    if (lis3dh_init(&lis)) {
+        /* error handling */
+    }
+
+    /* reset just in case*/
+    if (lis3dh_reset(&lis)) {
+        /* error handling */
+    }
+    
+    /* register interrupt */
+    if (int_register(GPIO_INTERRUPT_PIN_INT1)) {
+        /* error handling */
+    }
+
+    lis.cfg.mode = LIS3DH_MODE_HR;
+    lis.cfg.range = LIS3DH_FS_2G;
+    lis.cfg.rate = LIS3DH_ODR_100_HZ;
+    lis.cfg.pin1.overrun = 1;
+    lis.cfg.fifo.mode = LIS3DH_FIFO_MODE_STREAM;
+    lis.cfg.fifo.trig = LIS3DH_FIFO_TRIG_INT1;
+
+    /* write cfg to device */
+    if (lis3dh_configure(&lis)) {
+        /* error handling */
+    }
+
+    for ( ;; ) {
+
+        /* wait until FIFO overrun interrupt is active */
+        if (int_poll(GPIO_INTERRUPT_PIN_INT1)) {
+            /* error handling */
+        }
+
+        /* read FIFO into `fifo_data' struct `fifo' */
+        if (lis3dh_read_fifo(&lis, &fifo)) {
+            /* error handling */
+        }
+
+        /* print data .. */
+        for(i=0; i<fifo.size; i++) {
+            printf("x: %4.4d mg, y: %4.4d mg, z: %4.4d mg\n", fifo.x[i], fifo.y[i], fifo.z[i]);
+        }
+
+        printf("fifo.size=%d\n", fifo.size);
+
+        /* No need to reset the FIFO engine in stream mode */
+    }
+
+    /* deinitalise device */
+    if (lis3dh_deinit(&lis)) {
+        /* error handling */
+    }
+
+    return 0;
+}

example/fifo/stream-int-wtm.c

@@ -0,0 +1,79 @@
+#define _GNU_SOURCE /* usleep() */
+#include <unistd.h> /* usleep() */
+#include <stdio.h>
+#include "lis3dh.h"
+#include "i2c.h"
+#include "interrupt.h"
+
+/* Raspberry Pi GPIO pin connected to LIS3DH INT1 pin */
+#define GPIO_INTERRUPT_PIN_INT1 12
+
+int main() {
+
+    lis3dh_t lis;
+    struct lis3dh_fifo_data fifo;
+    int i;
+
+    lis.dev.init = i2c_init;
+    lis.dev.read = i2c_read;
+    lis.dev.write = i2c_write;
+    lis.dev.sleep = usleep;
+    lis.dev.deinit = i2c_deinit;
+
+    /* initialise struct and check device id */
+    if (lis3dh_init(&lis)) {
+        /* error handling */
+    }
+
+    /* reset just in case*/
+    if (lis3dh_reset(&lis)) {
+        /* error handling */
+    }
+    
+    /* register interrupt */
+    if (int_register(GPIO_INTERRUPT_PIN_INT1)) {
+        /* error handling */
+    }
+
+    lis.cfg.mode = LIS3DH_MODE_HR;
+    lis.cfg.range = LIS3DH_FS_2G;
+    lis.cfg.rate = LIS3DH_ODR_100_HZ;
+    lis.cfg.pin1.wtm = 1; /* watermark interrupt */
+    lis.cfg.fifo.mode = LIS3DH_FIFO_MODE_STREAM;
+    lis.cfg.fifo.trig = LIS3DH_FIFO_TRIG_INT1;
+    lis.cfg.fifo.size = 15; /* size must be < 32 to use the watermark interrupt */
+
+    /* write cfg to device */
+    if (lis3dh_configure(&lis)) {
+        /* error handling */
+    }
+
+    for ( ;; ) {
+
+        /* wait until FIFO overrun interrupt is active */
+        if (int_poll(GPIO_INTERRUPT_PIN_INT1)) {
+            /* error handling */
+        }
+
+        /* read FIFO into `fifo_data' struct `fifo' */
+        if (lis3dh_read_fifo(&lis, &fifo)) {
+            /* error handling */
+        }
+
+        /* print data .. */
+        for(i=0; i<fifo.size; i++) {
+            printf("x: %4.4d mg, y: %4.4d mg, z: %4.4d mg\n", fifo.x[i], fifo.y[i], fifo.z[i]);
+        }
+
+        printf("fifo.size=%d\n", fifo.size);
+
+        /* No need to reset the FIFO engine in stream mode */
+    }
+
+    /* deinitalise device */
+    if (lis3dh_deinit(&lis)) {
+        /* error handling */
+    }
+
+    return 0;
+}

example/fifo/stream.c

@@ -0,0 +1,66 @@
+#define _GNU_SOURCE /* usleep() */
+#include <unistd.h> /* usleep() */
+#include <stdio.h>
+#include "lis3dh.h"
+#include "i2c.h"
+
+int main() {
+
+    lis3dh_t lis;
+    struct lis3dh_fifo_data fifo;
+    int i;
+
+    lis.dev.init = i2c_init;
+    lis.dev.read = i2c_read;
+    lis.dev.write = i2c_write;
+    lis.dev.sleep = usleep;
+    lis.dev.deinit = i2c_deinit;
+
+    /* initialise struct and check device id */
+    if (lis3dh_init(&lis)) {
+        /* error handling */
+    }
+
+    /* reset just in case*/
+    if (lis3dh_reset(&lis)) {
+        /* error handling */
+    }
+
+    lis.cfg.mode = LIS3DH_MODE_HR;
+    lis.cfg.range = LIS3DH_FS_2G;
+    lis.cfg.rate = LIS3DH_ODR_100_HZ;
+    lis.cfg.fifo.mode = LIS3DH_FIFO_MODE_STREAM;
+
+    /* modifying the size of the FIFO buffer is not useful when just polling without interrupts */
+
+    /* write cfg to device */
+    if (lis3dh_configure(&lis)) {
+        /* error handling */
+    }
+
+    for ( ;; ) {
+
+        /* read FIFO into `fifo_data' struct `fifo' */
+        if (lis3dh_read_fifo(&lis, &fifo)) {
+            /* error handling */
+        }
+
+        /* print data .. */
+        for(i=0; i<fifo.size; i++) {
+            printf("x: %4.4d mg, y: %4.4d mg, z: %4.4d mg\n", fifo.x[i], fifo.y[i], fifo.z[i]);
+        }
+
+        /* FIFO size will rarely go above 2 in this example, because lis3dh_read_fifo() */
+        /* does not wait for the FIFO buffer to be full, just non-empty. */
+        printf("fifo.size=%d\n", fifo.size);
+
+        /* No need to reset the FIFO engine in stream mode */
+    }
+
+    /* deinitalise device */
+    if (lis3dh_deinit(&lis)) {
+        /* error handling */
+    }
+
+    return 0;
+}