working streaming of raw accel/gyro data. must restart firmware after run of test_basic.py

firmware/app/src/bt_services.c

@@ -0,0 +1,64 @@
+
+#include <zephyr/types.h>
+#include <stddef.h>
+#include <string.h>
+#include <errno.h>
+#include <zephyr/sys/printk.h>
+#include <zephyr/sys/byteorder.h>
+#include <zephyr/kernel.h>
+
+#include <zephyr/bluetooth/bluetooth.h>
+#include <zephyr/bluetooth/hci.h>
+#include <zephyr/bluetooth/conn.h>
+#include <zephyr/bluetooth/uuid.h>
+#include <zephyr/bluetooth/gatt.h>
+
+#include "bt_services.h"
+
+#include <zephyr/logging/log.h>
+
+LOG_MODULE_DECLARE(main, CONFIG_APP_LOG_LEVEL);
+
+static sensors_raw_t sensors;
+
+void set_sensors(const sensors_raw_t *values)
+{
+    sensors = *values;
+}
+
+// Callback definitions
+static ssize_t read_sensors(struct bt_conn *conn, const struct bt_gatt_attr *attr, void *buf,
+                            uint16_t len, uint16_t offset)
+{
+    const char *value = attr->user_data;
+    size_t size = sizeof(sensors_raw_t);
+
+    LOG_INF("Attribute read, handle: %u, conn: %p, bytes: %d", attr->handle, (void *)conn, size);
+
+    return bt_gatt_attr_read(conn, attr, buf, len, offset, value, size);
+}
+
+// Service declaration
+
+static ssize_t read_string(struct bt_conn *conn, const struct bt_gatt_attr *attr, void *buf, uint16_t len, uint16_t offset)
+{
+    const char *value = attr->user_data;
+    LOG_INF("String read, handle: %u, conn: %p\t%s", attr->handle, (void *)conn, value);
+    return bt_gatt_attr_read(conn, attr, buf, len, offset, attr->user_data, strlen((char *)attr->user_data));
+}
+
+BT_GATT_SERVICE_DEFINE(my_lbs_svc, BT_GATT_PRIMARY_SERVICE(BT_UUID_IMU),
+                       // Read raw sensor values
+                       BT_GATT_CHARACTERISTIC(BT_UUID_IMU_SENSORS,
+                                              BT_GATT_CHRC_READ,
+                                              BT_GATT_PERM_READ,
+                                              read_sensors,
+                                              NULL,
+                                              &sensors),
+                       BT_GATT_DESCRIPTOR(BT_UUID_GATT_CUD,
+                                          BT_GATT_PERM_READ,
+                                          read_string,
+                                          NULL,
+                                          "Read raw sensor values"),
+                       // TODO: add characteristic to read state estimate
+);