Python - 连接 BLE 设备

Question

正如标题所示，我有一个希望通过 python 脚本连接的 BLE 设备。我正在使用 Raspberry Pi 并安装了最新版本的 Bluez。

我已使用 Bluepy 连接到不同的 BLE 设备，但遗憾的是，我无法使用我拥有的当前 BLE 使用此方法检索任何数据，这就是我想以不同方式连接到它的原因。

我已经使用 GATTTool 连接到新设备并成功获取数据，我知道有一些库可以在 python 脚本中促进与 GATTTool 的连接。我已经尝试过 pexpect 和 pygatt，但似乎都没有工作，因为它在建立连接之前就超时了。

这是我在网上找到的一段代码；

import pygatt.backends
from binascii import hexlify

def printIndication(handle, value):
    print('Indication received {} : {}'.format(hex(handle), hexlify(str(value))))

adapter = pygatt.backends.GATTToolBackend()
adapter.start()
while True:  
 try:
    device = adapter.connect('00:38:40:0A:00:04', 5)
    break
 except pygatt.exceptions.NotConnectedError:
    print('Waiting...')

device.subscribe('0002021-0000-1000-8000-00805f9b34fb', callback = printIndication, indication = True)
device.subscribe('00002022-0000-1000-8000-00805f9b34fb', callback = printIndication, indication = True)
device.subscribe('00002a19-0000-1000-8000-00805f9b34fb', callback = printIndication, indication = True)


device.disconnect()
adapter.stop()

当我执行代码时，我得到以下输出：

Traceback (most recent call last):
  File "./test.py", line 10, in <module>
    adapter.start()
  File "/usr/local/lib/python2.7/dist-packages/pygatt/backends/gatttool/gatttool.py", line 90, in start
   self._con.expect(r'\[LE\]>', timeout=1)
  File "/usr/lib/python2.7/dist-packages/pexpect/__init__.py", line 1418, in expect
    timeout, searchwindowsize)
  File "/usr/lib/python2.7/dist-packages/pexpect/__init__.py", line 1433, in expect_list
    timeout, searchwindowsize)
  File "/usr/lib/python2.7/dist-packages/pexpect/__init__.py", line 1535, in expect_loop
    raise TIMEOUT(str(err) + '\n' + str(self))
pexpect.TIMEOUT: Timeout exceeded.
<pexpect.spawn object at 0x76737730>
version: 3.2
command: /usr/bin/gatttool
args: ['/usr/bin/gatttool', '-i', 'hci0', '-I']
searcher: <pexpect.searcher_re object at 0x76737770>
buffer (last 100 chars): ''
before (last 100 chars): ''
after: <class 'pexpect.TIMEOUT'>
match: None
match_index: None
exitstatus: None
flag_eof: False
pid: 5062
child_fd: 3
closed: False
timeout: 30
delimiter: <class 'pexpect.EOF'>
logfile: None
logfile_read: None
logfile_send: None
maxread: 2000
ignorecase: False
searchwindowsize: None
delaybeforesend: 0.05
delayafterclose: 0.1
delayafterterminate: 0.1

我也试过下面的代码：

import pygatt.backends

# The BGAPI backend will attemt to auto-discover the serial device name of the
# attached BGAPI-compatible USB adapter.
adapter = pygatt.backends.GATTToolBackend()
adapter.start()
device = adapter.connect('01:23:45:67:89:ab')
value = device.char_read("a1e8f5b1-696b-4e4c-87c6-69dfe0b0093b")

执行此代码后，我得到了完全相同的错误。我尝试更改超时，但似乎没有什么不同，所发生的只是它等待分配的时间并且将显示相同的输出。

我错过了什么？有没有更好的方法来做到这一点？

在此先感谢您提供的任何帮助。

Answer 1

现在可能为时已晚，但如果有人有同样的疑问，您可以使用 pexpect 库。我会留下一些适用于我的示例代码（我可以读取从 PSOC 4200 ble 设备发送的一些数据）。

import pexpect
DEVICE = "00:A0:50:CF:62:CD"   # address of your device
if len(sys.argv) == 2:
  DEVICE = str(sys.argv[1])
# Run gatttool interactively.
child = pexpect.spawn("gatttool -I")

# Connect to the device.
print("Connecting to:"),
print(DEVICE)
NOF_REMAINING_RETRY = 3
while True:
  try:
    child.sendline("connect {0}".format(DEVICE))
    child.expect("Connection successful", timeout=5)
  except pexpect.TIMEOUT:
    NOF_REMAINING_RETRY = NOF_REMAINING_RETRY-1
    if (NOF_REMAINING_RETRY>0):
      print "timeout, retry..."
      continue
    else:
      print "timeout, giving up."
      break
  else:
    print("Connected!")
    break

然后要阅读一些东西，只需这样做：

# Presence Sensor
  child.sendline("char-read-hnd 0x16") # put the handle you want to read
  child.expect("Characteristic value/descriptor: ", timeout=5)
  child.expect("\r\n", timeout=5)
  print("Presence Sensor:  "),
  print(child.before),
  print(chr(int(child.before[0:2],16)))