server.c

/**
 * Copyright (c) 2023 Raspberry Pi (Trading) Ltd.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

#include <stdio.h>
#include "btstack.h"
#include "pico/cyw43_arch.h"
#include "pico/btstack_cyw43.h"
#include "pico/stdlib.h"
#include "doorbell.h" // generated by pico_btstack_make_gatt_header in CMakeLists.txt
#include "hardware/gpio.h"


#define HEARTBEAT_PERIOD_MS 1000
#define APP_AD_FLAGS 0x06
#define BUTTON_GPIO_NUM 15

#ifndef NDEBUG
#define DEBUG_LOG printf
#else
#define DEBUG_LOG(...)
#endif

static uint8_t adv_data[] = {
    // Flags general discoverable
    0x02, BLUETOOTH_DATA_TYPE_FLAGS, APP_AD_FLAGS,
    // Name
    0x17, BLUETOOTH_DATA_TYPE_COMPLETE_LOCAL_NAME, 'P', 'i', 'c', 'o', ' ', '0', '0', ':', '0', '0', ':', '0', '0', ':', '0', '0', ':', '0', '0', ':', '0', '0',
    0x03, BLUETOOTH_DATA_TYPE_COMPLETE_LIST_OF_16_BIT_SERVICE_CLASS_UUIDS, 0x3b, 0x18,
};

static const uint8_t adv_data_len = sizeof(adv_data);

static bool le_notification_enabled;
static uint16_t current_state;
static hci_con_handle_t con_handle;
extern uint8_t const profile_data[];

static btstack_timer_source_t heartbeat;
static btstack_packet_callback_registration_t hci_event_callback_registration;

static void packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size) {
    UNUSED(size);
    UNUSED(channel);
    bd_addr_t local_addr;
    if (packet_type != HCI_EVENT_PACKET) return;

    uint8_t event_type = hci_event_packet_get_type(packet);
    switch(event_type){
        case BTSTACK_EVENT_STATE:
            if (btstack_event_state_get_state(packet) != HCI_STATE_WORKING) return;
            gap_local_bd_addr(local_addr);
            DEBUG_LOG("BTstack up and running on %s.\n", bd_addr_to_str(local_addr));

            // setup advertisements
            uint16_t adv_int_min = 800;
            uint16_t adv_int_max = 800;
            uint8_t adv_type = 0;
            bd_addr_t null_addr;
            memset(null_addr, 0, 6);
            gap_advertisements_set_params(adv_int_min, adv_int_max, adv_type, 0, null_addr, 0x07, 0x00);
            assert(adv_data_len <= 31); // ble limitation
            gap_advertisements_set_data(adv_data_len, (uint8_t*) adv_data);
            gap_advertisements_enable(1);


            break;
        case HCI_EVENT_DISCONNECTION_COMPLETE:
            le_notification_enabled = 0;
            break;
        case ATT_EVENT_CAN_SEND_NOW:
            att_server_notify(con_handle, ATT_CHARACTERISTIC_ORG_BLUETOOTH_CHARACTERISTIC_DIGITAL_OUTPUT_01_VALUE_HANDLE, (uint8_t*)&current_state, sizeof(current_state));
            break;
        default:
            break;
    }
}

static uint16_t att_read_callback(hci_con_handle_t connection_handle, uint16_t att_handle, uint16_t offset, uint8_t * buffer, uint16_t buffer_size) {
    UNUSED(connection_handle);

    if (att_handle == ATT_CHARACTERISTIC_ORG_BLUETOOTH_CHARACTERISTIC_DIGITAL_OUTPUT_01_VALUE_HANDLE){
        return att_read_callback_handle_blob((const uint8_t *)&current_state, sizeof(current_state), offset, buffer, buffer_size);
    }
    return 0;
}

static int att_write_callback(hci_con_handle_t connection_handle, uint16_t att_handle, uint16_t transaction_mode, uint16_t offset, uint8_t *buffer, uint16_t buffer_size) {
    UNUSED(transaction_mode);
    UNUSED(offset);
    UNUSED(buffer_size);
    
    if (att_handle != ATT_CHARACTERISTIC_ORG_BLUETOOTH_CHARACTERISTIC_DIGITAL_OUTPUT_01_CLIENT_CONFIGURATION_HANDLE) return 0;
    le_notification_enabled = little_endian_read_16(buffer, 0) == GATT_CLIENT_CHARACTERISTICS_CONFIGURATION_NOTIFICATION;
    con_handle = connection_handle;
    DEBUG_LOG("att_write_callback notifications enabled %d\n", le_notification_enabled);
    if (le_notification_enabled) {
        att_server_request_can_send_now_event(con_handle);
    }
    return 0;
}

static void doorbell_notification_fn(__unused void * arg) {
    att_server_request_can_send_now_event(con_handle);
}
static btstack_context_callback_registration_t doorbell_notification = { .callback = doorbell_notification_fn };

static void button_irq_handler(uint gpio, uint32_t events) {
    uint16_t new_state = 0;
    if (events & GPIO_IRQ_EDGE_FALL) new_state = 1;
    if (events & GPIO_IRQ_EDGE_RISE) new_state = 0;
    if (current_state != new_state) {
        current_state = new_state;
        DEBUG_LOG("button_irq_handler state %u notifications enabled %d\n", current_state, le_notification_enabled);
        if (le_notification_enabled) {
            // We want to call att_server_request_can_send_now_event,
            // but we are in an IRQ and so it's dangerous to call BTStack directly from here.
            // So we ask BTstack to callback a function from the "main thread"
            // We could also use an async (when pending) worker using async_when_pending_worker_t,
            // async_context_add_when_pending_worker and async_context_set_work_pending
            btstack_run_loop_execute_on_main_thread(&doorbell_notification);
        }
    }
}

static void heartbeat_handler(struct btstack_timer_source *ts) {
    static uint32_t counter = 0;
    counter++;
   
    // Invert the led
    static int led_on = true;
    led_on = !led_on;
    cyw43_arch_gpio_put(CYW43_WL_GPIO_LED_PIN, led_on);

    // Restart timer
    btstack_run_loop_set_timer(ts, HEARTBEAT_PERIOD_MS);
    btstack_run_loop_add_timer(ts);
}

int main() {
    stdio_init_all();

    gpio_init(BUTTON_GPIO_NUM);
    gpio_set_dir(BUTTON_GPIO_NUM, GPIO_IN);
    gpio_pull_up(BUTTON_GPIO_NUM);
    gpio_set_irq_enabled_with_callback(BUTTON_GPIO_NUM, GPIO_IRQ_EDGE_FALL|GPIO_IRQ_EDGE_RISE, true, &button_irq_handler);

    // initialize CYW43 driver architecture (will enable BT if/because CYW43_ENABLE_BLUETOOTH == 1)
    if (cyw43_arch_init()) {
        printf("failed to initialise cyw43_arch\n");
        return -1;
    }

    l2cap_init();
    sm_init();

    att_server_init(profile_data, att_read_callback, att_write_callback);    

    // inform about BTstack state
    hci_event_callback_registration.callback = &packet_handler;
    hci_add_event_handler(&hci_event_callback_registration);

    // register for ATT event
    att_server_register_packet_handler(packet_handler);

    // set one-shot btstack timer
    heartbeat.process = &heartbeat_handler;
    btstack_run_loop_set_timer(&heartbeat, HEARTBEAT_PERIOD_MS);
    btstack_run_loop_add_timer(&heartbeat);

    // turn on bluetooth!
    hci_power_control(HCI_POWER_ON);
    
    // btstack_run_loop_execute is only required when using the 'polling' method (e.g. using pico_cyw43_arch_poll library).
    // This example uses the 'threadsafe background` method, where BT work is handled in a low priority IRQ, so it
    // is fine to call bt_stack_run_loop_execute() but equally you can continue executing user code.

#if 0 // btstack_run_loop_execute() is not required, so lets not use it
    btstack_run_loop_execute();
#else
    // this core is free to do it's own stuff except when using 'polling' method (in which case you should use 
    // btstacK_run_loop_ methods to add work to the run loop.
    
    // this is a forever loop in place of where user code would go.
    while(true) {      
        sleep_ms(1000);
    }
#endif
    return 0;
}