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Reply-To: yunhanw@nestlabs.com
From: Yunhan Wang <yunhanw@nestlabs.com>
Date: Sun, 6 Aug 2017 01:25:07 -0700
Message-ID: <CALvjcs-BQKBVRe9oJ_1aG2h5DuH04TyvX8bYJjs92vhSVYDgig@mail.gmail.com>
Subject: bluetoothctl: how to send notification/indcation from peripheral to central
To: linux-bluetooth@vger.kernel.org
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Sender: linux-bluetooth-owner@vger.kernel.org
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Hi

Has any one been able to send notification from LE peripheral to LE
central using bluetoothctl?

Now I am trying to update "Value" with 0x02 for the below
characteristic with read and indicate flag, i am expecting a
notification can be sent from peripheral to central automatically. It
seems there is no such support in bluetoothctl. Then I do simple code
change on below, and try to update value via "update-chrc 0x02", well,
the value has been successfully updated, but there is no
message/notification sent from peripheral to central automatically. I
have confirmed that chrc read from central is showing updated value,
02, correctly. The question is that how can we send characteristic
notification/indication using bluez dbus API?

btw, I see the video(BlueZ Meets Zephyr made by Luiz)
https://www.youtube.com/watch?v=SdmZX5q-XDg
In 30:05, I see Zephyr is sending notification to bluetoothctl
automatically. How can we just use bluez dbus API to achieve this?

for example,
In LE peripheral:
I setup the below characteristic with read and indicate flag
register-service 00001820-0000-1000-8000-00805f9b34fb
register-characteristic 00002a06-0000-1000-8000-00805f9b34fb read,indicate
register-application
advertise peripheral

In LE central:
connect 00:AA:01:00:00:23
select-attribute /org/bluez/hci1/dev_00_AA_01_00_00_23/service000a/char000b
notify on

The code change snippet
--- a/client/gatt.c
+++ b/client/gatt.c
-void gatt_register_chrc(DBusConnection *conn, GDBusProxy *proxy, wordexp_t *w)
+void chrc_set_value1(const char *input, void *user_data, DBusConnection *conn)
+{
+    struct chrc *chrc = user_data;
+
+    g_free(chrc->value);
+
+    chrc->value = str2bytearray((char *) input, &chrc->value_len);
+    g_dbus_emit_property_changed(conn, chrc->path,
"org.bluez.GattCharacteristic1", "Value");
+
+}
+struct chrc * gatt_register_chrc(DBusConnection *conn, GDBusProxy
*proxy, wordexp_t *w)
 {
        struct service *service;
        struct chrc *chrc;
@@ -1489,6 +1500,8 @@ void gatt_register_chrc(DBusConnection *conn,
GDBusProxy *proxy, wordexp_t *w)
        print_chrc(chrc, COLORED_NEW);

        rl_prompt_input(chrc->path, "Enter value:", chrc_set_value, chrc);
+
+    return chrc;
 }

--- a/client/main.c
+++ b/client/main.c
+static void cmd_update_chrc(const char *arg)
+{
+    chrc_set_value1(arg, default_chrc, dbus_conn);
+
+}
+
 static void cmd_unregister_characteristic(const char *arg)
 {
        wordexp_t w;
@@ -2541,6 +2547,9 @@ static const struct {
        { "register-characteristic", "<UUID> <Flags=read,write,notify...>",
                                        cmd_register_characteristic,
                                        "Register application characteristic" },
+    { "update-chrc", "<value.>",
+            cmd_update_chrc,
+            "update chrc value" },

Thanks
Best wishes
Yunhan