树莓派 3 BLE 扫描

Question

我正在尝试在 Raspberry Pi 3 中实现下一个代码以扫描 BLE 设备：

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/socket.h>
#include <bluetooth/bluetooth.h>
#include <bluetooth/hci.h>
#include <bluetooth/hci_lib.h>

int main(int argc, char **argv)
{
    inquiry_info *ii = NULL;
    int max_rsp, num_rsp;
    int dev_id, sock, len, flags;
    int i;
    char addr[19] = { 0 };
    char name[248] = { 0 };

    dev_id = hci_get_route(NULL);
    sock = hci_open_dev( dev_id );
    if (dev_id < 0 || sock < 0) {
        perror("opening socket");
        exit(1);
    }

    len  = 8;
    max_rsp = 255;
    flags = IREQ_CACHE_FLUSH;
    ii = (inquiry_info*)malloc(max_rsp * sizeof(inquiry_info));

    num_rsp = hci_inquiry(dev_id, len, max_rsp, NULL, &ii, flags);
    if( num_rsp < 0 ) perror("hci_inquiry");

    for (i = 0; i < num_rsp; i++) {
        ba2str(&(ii+i)->bdaddr, addr);
        memset(name, 0, sizeof(name));
        if (hci_read_remote_name(sock, &(ii+i)->bdaddr, sizeof(name), 
            name, 0) < 0)
        strcpy(name, "[unknown]");
        printf("%s  %s\n", addr, name);
    }

    free( ii );
    close( sock );
    return 0;
}

问题是num_rsp等于0，也就是没有找到任何设备。

但是，如果我在终端中使用命令$ sudo hcitool lescan，它会找到所有可用的设备。

谁能指出我解决此问题的正确方向？有没有其他方法可以将hcitool lescan 实现为 C++ 代码？

提前致谢。

Answer 1

使用 BlueZ，您可以使用 hci_le_set_scan_parameters 和 hci_le_set_scan_enable 触发 BLE 扫描。

Here is an experiment written in C

if (hci_le_set_scan_parameters(current_hci_state.device_handle, 0x01, htobs(0x0010), htobs(0x0010), 0x00, 0x00, 1000) < 0)
{
    current_hci_state.has_error = 1;
    snprintf(current_hci_state.error_message, sizeof(current_hci_state.error_message), "Failed to set scan parameters: %s", strerror(errno));
    return;
}

if (hci_le_set_scan_enable(current_hci_state.device_handle, 0x01, 1, 1000) < 0)
{
    current_hci_state.has_error = 1;
    snprintf(current_hci_state.error_message, sizeof(current_hci_state.error_message), "Failed to enable scan: %s", strerror(errno));
    return;
}

我已经用 C++ 移植了这个例子 here

Answer 2

NewAer SDK 支持 Pi 3 和 iOS 设备之间的 BLE 扫描和 P2P 通信。 SDK 也支持 Android，但由于操作系统处理 BLE 模式的方式，支持有限。