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draft docu for LE Counter
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Matthias Ringwald
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@ -36,10 +36,14 @@
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*/
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// *****************************************************************************
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/* EXAMPLE_START(le_counter): Dual mode example
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/* EXAMPLE_START(le_counter): LE Peripheral - Heartbeat Counter over GATT
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*
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* @text All newer operating systems provide GATT Client functionality.
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* The LE Counter examples demonstrates how to specify a minimal GATT Database
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* with a custom GATT Service and a custom Characteristic that sends periodic
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* notifications.
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*/
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// *****************************************************************************
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// *****************************************************************************
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#include <stdint.h>
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#include <stdio.h>
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@ -68,22 +72,32 @@
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#define HEARTBEAT_PERIOD_MS 1000
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static int le_notification_enabled;
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/* LISTING_START(notificationFlag): Notification Flag */
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static int le_notification_enabled;
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/* LISTING_END */
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// THE Couner
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static timer_source_t heartbeat;
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static int counter = 0;
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static char counter_string[30];
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static int counter_string_len;
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/*
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* @section Managing LE Advertisements
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*
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* @text To be discoverable, LE Advertisements are enabled using direct HCI Commands.
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* As there's no guarantee that a HCI command can always be sent, the gap_run function
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* is used to send each command as requested by the $todos$ variable.
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* First, the advertisement data is set, then the advertisement params incl. the
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* advertisement interval is set. Finally, advertisements are enabled. See Listing gapRun.
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*
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* In this example, the Advertisement contains the Flags attribute and the device name.
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* The flag 0x06 indicates: LE General Discoverable Mode and BR/EDR not supported.
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*/
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/* LISTING_START(gapRun): Handle GAP Tasks */
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const uint8_t adv_data[] = {
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// Flags general discoverable
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0x02, 0x01, 0x02,
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0x02, 0x01, 0x06,
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// Name
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0x0b, 0x09, 'L', 'E', ' ', 'C', 'o', 'u', 'n', 't', 'e', 'r',
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};
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uint8_t adv_data_len = sizeof(adv_data);
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uint8_t adv_data_len = sizeof(adv_data);
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enum {
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SET_ADVERTISEMENT_PARAMS = 1 << 0,
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SET_ADVERTISEMENT_DATA = 1 << 1,
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@ -91,7 +105,6 @@ enum {
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};
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static uint16_t todos = 0;
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static void gap_run(){
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if (!hci_can_send_command_packet_now()) return;
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@ -121,7 +134,18 @@ static void gap_run(){
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return;
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}
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}
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/* LISTING_END */
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/*
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* @section Packet Handler
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*
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* @text The packet handler is only used to trigger advertisements after BTstack is ready and after disconnects.
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* See Listing packetHandler.
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* Advertisemetns are not automatically re-enabled after a connection was closed although it was active before.
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*
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*/
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/* LISTING_START(packetHandler): Packet Handler */
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static void packet_handler (void * connection, uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
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switch (packet_type) {
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case HCI_EVENT_PACKET:
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@ -151,6 +175,45 @@ static void packet_handler (void * connection, uint8_t packet_type, uint16_t cha
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}
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gap_run();
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}
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/* LISTING_END */
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/*
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* @section Hearbeat Handler
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*
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* @text The hearbeat handler updates the value of the single Characteristic provided in this example
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* and sends a notification for this characteristic if enabled. See Listing heartbeat.
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*/
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/* LISTING_START(heartbeat): Hearbeat Handler */
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static timer_source_t heartbeat;
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static int counter = 0;
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static char counter_string[30];
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static int counter_string_len;
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static void heartbeat_handler(struct timer *ts){
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counter++;
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counter_string_len = sprintf(counter_string, "BTstack counter %04u\n", counter);
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puts(counter_string);
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if (le_notification_enabled) {
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att_server_notify(ATT_CHARACTERISTIC_0000FF11_0000_1000_8000_00805F9B34FB_01_VALUE_HANDLE, (uint8_t*) counter_string, counter_string_len);
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}
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run_loop_set_timer(ts, HEARTBEAT_PERIOD_MS);
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run_loop_add_timer(ts);
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}
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/* LISTING_END */
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/*
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* @section ATT Read
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*
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* The ATT Server handles all reads to constant data. For dynamic data like the custom characteristic, the registered
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* att_read_callback is called. To handle long characteristics and long reads, the att_read_callback is first called
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* with buffer == NULL, to request the total value lenght. Then it will be called again requesting a chunk of the value.
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* See Listing attRead.
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*/
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/* LISTING_START(attRead): ATT Read */
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// ATT Client Read Callback for Dynamic Data
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// - if buffer == NULL, don't copy data, just return size of value
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@ -165,29 +228,35 @@ static uint16_t att_read_callback(uint16_t con_handle, uint16_t att_handle, uint
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}
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return 0;
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}
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/* LISTING_END */
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// write requests
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/*
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* @section ATT Write
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*
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* @text The only valid att write in this example is to the Client Characteristic Configuration, which configures notification
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* and indication. If the att_handle matches the client configuration handle, the new configuration value is stored and used
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* in the hearbeat handler to decide if a new value should be sent. See Listing attWrite
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*/
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/* LISTING_START(attWrite): ATT Write */
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static int att_write_callback(uint16_t con_handle, uint16_t att_handle, uint16_t transaction_mode, uint16_t offset, uint8_t *buffer, uint16_t buffer_size){
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// printf("WRITE Callback, handle %04x, mode %u, offset %u, data: ", handle, transaction_mode, offset);
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// printf_hexdump(buffer, buffer_size);
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if (att_handle != ATT_CHARACTERISTIC_0000FF11_0000_1000_8000_00805F9B34FB_01_CLIENT_CONFIGURATION_HANDLE) return 0;
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le_notification_enabled = READ_BT_16(buffer, 0) == GATT_CLIENT_CHARACTERISTICS_CONFIGURATION_NOTIFICATION;
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return 0;
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}
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/* LISTING_END */
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static void heartbeat_handler(struct timer *ts){
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counter++;
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counter_string_len = sprintf(counter_string, "BTstack counter %04u\n", counter);
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puts(counter_string);
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if (le_notification_enabled) {
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att_server_notify(ATT_CHARACTERISTIC_0000FF11_0000_1000_8000_00805F9B34FB_01_VALUE_HANDLE, (uint8_t*) counter_string, counter_string_len);
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}
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run_loop_set_timer(ts, HEARTBEAT_PERIOD_MS);
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run_loop_add_timer(ts);
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}
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// main == setup
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/* @section Main app setup
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*
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* @text Listing MainConfiguration shows main application code.
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* It initializes L2CAP, the Security Manager and configures the ATT Server with the pre-compiled
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* ATT Database generated from $le_counter.gatt$. Finally, it configures the heartbeat handler and
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* boots the Bluetooth stack.
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*/
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/* LISTING_START(MainConfiguration): Setup heartbeat timer */
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int btstack_main(void);
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int btstack_main(void)
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{
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@ -213,4 +282,5 @@ int btstack_main(void)
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return 0;
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}
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/* LISTING_END */
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/* EXAMPLE_END */
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