本文章介紹在Raspberry Pi Pico W 使用Btstack來實現使用BLE的Advertisement來發送安裝在BLE peripheral(broadcaster)上的溫濕度sensor的數據給所有centrals(observers)。
本實驗使用一個Raspberry Pi Pico W連接DHT11，把收集到環境的溫濕度透過BLE advertisement給附近所有的BLE observer。
另一個Raspberry Pi Pico W當作Central(Observer)接收advertisement data顯示在TFT上。
另一個Android Phone安裝Nordic nRF Connect scan 附近BLE broadcaster並顯示收集到的資料。
本實驗僅透過Advertisement data來傳送資料，不需要connect BLE peripheral。
每一個advertisement資料結構分成三個欄位：length, type and data。在本實驗中相對應程式的結構如下：
2. UUID 0x2A6F表示一個byte的濕度資料。
Peripheral端設定advertisement param, data後enable advertisement。
Central端設定HCI packet handler處理 GAP_EVENT_ADVERTISING_REPORT。讀取advertisement data and size。
使用BTstack ad_iterator_* 等functions來取得advertisement packet每的資料夠的
成果展示影片：
程式碼：
1. Peripheral(broadcaster)端：
#include <stdio.h>
#include "pico/stdlib.h"
#include "btstack.h"
#include "pico/cyw43_arch.h"
#include "dht11/dht11.h"
#include "math.h"
#include "stdlib.h"
#define ADV_TEMP_HUMI_PERIOD_MS 3000
uint8_t adv_data[] = {
// Flags: 0x02: General Discoverable Mode, 0x04:BR/EDR Not Supported
0x02, BLUETOOTH_DATA_TYPE_FLAGS, 0x06,
// Name
0x0a, BLUETOOTH_DATA_TYPE_COMPLETE_LOCAL_NAME, 'P', 'i', 'c', 'o', 'W', '-', 'B', 'L', 'E',
0x03, BLUETOOTH_DATA_TYPE_INCOMPLETE_LIST_OF_16_BIT_SERVICE_CLASS_UUIDS, 0x1a, 0x18,
//Temperature UUID:0x2A5E
0x04, BLUETOOTH_DATA_TYPE_SERVICE_DATA, 0x6E,0x2A,0x00,
//Humidity UUID: 0x2A6F
0x04, BLUETOOTH_DATA_TYPE_SERVICE_DATA, 0x6F,0x2A,0x00,
};
uint8_t adv_data_len = sizeof(adv_data);
static btstack_timer_source_t adv_temp_humi;
uint8_t temp=0, humi=0;
static void adv_temp_humi_handler(struct btstack_timer_source *ts){
//gap_advertisements_enable(false);
float t,h;
if (dht11_get_data(&t, &h)) {
temp = (int)round(t);
humi = (int)h;
}
adv_data[adv_data_len-1] = humi;
adv_data[adv_data_len-6] = temp;
printf("Temp:%d °C, Humi:%d %c\n", temp, humi, '%');
gap_advertisements_set_data(adv_data_len, adv_data);
//gap_advertisements_enable(true);
btstack_run_loop_set_timer(ts, ADV_TEMP_HUMI_PERIOD_MS);
btstack_run_loop_add_timer(ts);
}
int main()
{
stdio_init_all();
if (cyw43_arch_init()) {
printf("cyw43_init error\n");
return 0;
}
l2cap_init();
sm_init();
dht11_init();
// setup advertisements
uint16_t adv_int_min = 0x0030;
uint16_t adv_int_max = 0x0030;
// ADV_TYPE:
// 0b0000: ADV_IND, 0b0001: ADV_DIRECT_IND, 0b0010: ADV_NONCONN_IND, 0b0011: ADV_SCAN_IND
uint8_t adv_type = 2; // only advertisement, not connectable.
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);
gap_advertisements_set_data(adv_data_len, (uint8_t*) adv_data);
gap_advertisements_enable(true);
adv_temp_humi.process = &adv_temp_humi_handler;
btstack_run_loop_set_timer(&adv_temp_humi, ADV_TEMP_HUMI_PERIOD_MS);
btstack_run_loop_add_timer(&adv_temp_humi);
hci_power_control(HCI_POWER_ON);
while(1) {
tight_loop_contents();
}
return 0;
}2. Central(Observer)端：
#include <stdio.h>
#include "pico/stdlib.h"
#include "pico/cyw43_arch.h"
#include <stdint.h>
#include <inttypes.h>
#include <stdlib.h>
#include <string.h>
#include "btstack.h"
#include "fonts/font_fixedsys_mono_16.h"
#include "pico_tft.h"
#include "tft_string.h"
#define BROADCAST_DEVICE "PicoW-BLE"
static btstack_packet_callback_registration_t hci_event_callback_registration;
uint8_t broadcast_device_name[20];
uint8_t service_16_uuid[2];
uint8_t temp=0;
uint8_t humi=0;
bool bNewAdvData=false;
static void show_received_advertisement_data(const uint8_t * adv_data, uint8_t adv_size){
ad_context_t context;
for (ad_iterator_init(&context, adv_size, (uint8_t *)adv_data) ; ad_iterator_has_more(&context) ; ad_iterator_next(&context)){
uint8_t data_type = ad_iterator_get_data_type(&context);
uint8_t size = ad_iterator_get_data_len(&context);
const uint8_t * data = ad_iterator_get_data(&context);
switch (data_type) {
case BLUETOOTH_DATA_TYPE_COMPLETE_LOCAL_NAME:
memcpy(broadcast_device_name, data,size);
broadcast_device_name[size]='\0';
break;
case BLUETOOTH_DATA_TYPE_INCOMPLETE_LIST_OF_16_BIT_SERVICE_CLASS_UUIDS:
memcpy(service_16_uuid, data,size);
break;
case BLUETOOTH_DATA_TYPE_SERVICE_DATA:
if (data[0]==0x6E && data[1]==0x2A) {
temp = data[2];
}
if (data[0]==0x6F && data[1]==0x2A) {
humi = data[2];
}
break;
}
}
if (strcmp(broadcast_device_name, BROADCAST_DEVICE) == 0 &&
service_16_uuid[0]==0x1A && service_16_uuid[1]==0x18) {
bNewAdvData=true;
}
}
static void packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
UNUSED(channel);
UNUSED(size);
if (packet_type != HCI_EVENT_PACKET) return;
switch (hci_event_packet_get_type(packet)) {
case GAP_EVENT_ADVERTISING_REPORT:{
uint8_t length = gap_event_advertising_report_get_data_length(packet);
const uint8_t * data = gap_event_advertising_report_get_data(packet);
show_received_advertisement_data(data, length);
break;
}
default:
break;
}
}
uint8_t ts[50];
int main() {
stdio_init_all();
if (cyw43_arch_init()) {
printf("cyw43_init error\n");
return 0;
}
gap_set_scan_parameters(0,4800,48); // scan type: 0: passive, 1:active
//scan interval 0.625*n,
gap_start_scan();
hci_event_callback_registration.callback = &packet_handler;
hci_add_event_handler(&hci_event_callback_registration);
hci_power_control(HCI_POWER_ON);
tft_init();
while (1) {
if (bNewAdvData) {
bNewAdvData=false;
printf("local name:%s, temp=%d, humi=%d\n", broadcast_device_name, temp, humi);
tft_fill_rect(0,0,TFT_WIDTH, TFT_HEIGHT, 0xffff);
sprintf(ts, "Device:%s", broadcast_device_name);
tft_draw_string(2,10,ts, 0x001f, &font_fixedsys_mono_16);
sprintf(ts, "Temp:%02dC", temp);
tft_draw_string(2,50,ts, 0x001f, &font_fixedsys_mono_16);
sprintf(ts, "Humi:%02d%c", humi, '%');
tft_draw_string(2,80,ts, 0x001f, &font_fixedsys_mono_16);
}
}
}
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