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D'accord. Je l'ai compris. transfer.flags doit être un octet au lieu d'un int. Que je suis bête. Maintenant, je reçois un code d'erreur de ioctl, errno 16, qui, je pense, signifie que le périphérique est occupé. Quel bourreau de travail. J'ai demandé sur la liste de diffusion de libusb.Certains aident à comprendre les opérations USB asynchrones avec libusb-1.0 et ctypes
Voici ce que j'ai jusqu'à présent. Ce n'est pas vraiment beaucoup de code. La plupart sont des structures ctypes pour libusb. Faites défiler vers le bas pour voir le code réel où l'erreur se produit.
from ctypes import *
VENDOR_ID = 0x04d8
PRODUCT_ID = 0xc002
_USBLCD_MAX_DATA_LEN = 24
LIBUSB_ENDPOINT_IN = 0x80
LIBUSB_ENDPOINT_OUT = 0x00
class EnumerationType(type(c_uint)):
def __new__(metacls, name, bases, dict):
if not "_members_" in dict:
_members_ = {}
for key,value in dict.items():
if not key.startswith("_"):
_members_[key] = value
dict["_members_"] = _members_
cls = type(c_uint).__new__(metacls, name, bases, dict)
for key,value in cls._members_.items():
globals()[key] = value
return cls
def __contains__(self, value):
return value in self._members_.values()
def __repr__(self):
return "<Enumeration %s>" % self.__name__
class Enumeration(c_uint):
__metaclass__ = EnumerationType
_members_ = {}
def __init__(self, value):
for k,v in self._members_.items():
if v == value:
self.name = k
break
else:
raise ValueError("No enumeration member with value %r" % value)
c_uint.__init__(self, value)
@classmethod
def from_param(cls, param):
if isinstance(param, Enumeration):
if param.__class__ != cls:
raise ValueError("Cannot mix enumeration members")
else:
return param
else:
return cls(param)
def __repr__(self):
return "<member %s=%d of %r>" % (self.name, self.value, self.__class__)
class LIBUSB_TRANSFER_STATUS(Enumeration):
_members_ = {'LIBUSB_TRANSFER_COMPLETED':0,
'LIBUSB_TRANSFER_ERROR':1,
'LIBUSB_TRANSFER_TIMED_OUT':2,
'LIBUSB_TRANSFER_CANCELLED':3,
'LIBUSB_TRANSFER_STALL':4,
'LIBUSB_TRANSFER_NO_DEVICE':5,
'LIBUSB_TRANSFER_OVERFLOW':6}
class LIBUSB_TRANSFER_FLAGS(Enumeration):
_members_ = {'LIBUSB_TRANSFER_SHORT_NOT_OK':1<<0,
'LIBUSB_TRANSFER_FREE_BUFFER':1<<1,
'LIBUSB_TRANSFER_FREE_TRANSFER':1<<2}
class LIBUSB_TRANSFER_TYPE(Enumeration):
_members_ = {'LIBUSB_TRANSFER_TYPE_CONTROL':0,
'LIBUSB_TRANSFER_TYPE_ISOCHRONOUS':1,
'LIBUSB_TRANSFER_TYPE_BULK':2,
'LIBUSB_TRANSFER_TYPE_INTERRUPT':3}
class LIBUSB_CONTEXT(Structure):
pass
class LIBUSB_DEVICE(Structure):
pass
class LIBUSB_DEVICE_HANDLE(Structure):
pass
class LIBUSB_CONTROL_SETUP(Structure):
_fields_ = [("bmRequestType", c_int),
("bRequest", c_int),
("wValue", c_int),
("wIndex", c_int),
("wLength", c_int)]
class LIBUSB_ISO_PACKET_DESCRIPTOR(Structure):
_fields_ = [("length", c_int),
("actual_length", c_int),
("status", LIBUSB_TRANSFER_STATUS)]
class LIBUSB_TRANSFER(Structure):
pass
LIBUSB_TRANSFER_CB_FN = CFUNCTYPE(c_void_p, POINTER(LIBUSB_TRANSFER))
LIBUSB_TRANSFER._fields_ = [("dev_handle", POINTER(LIBUSB_DEVICE_HANDLE)),
("flags", c_ubyte),
("endpoint", c_ubyte),
("type", c_ubyte),
("timeout", c_uint),
("status", LIBUSB_TRANSFER_STATUS),
("length", c_int),
("actual_length", c_int),
("callback", LIBUSB_TRANSFER_CB_FN),
("user_data", c_void_p),
("buffer", POINTER(c_ubyte)),
("num_iso_packets", c_int),
("iso_packet_desc", POINTER(LIBUSB_ISO_PACKET_DESCRIPTOR))]
class TIMEVAL(Structure):
_fields_ = [('tv_sec', c_long), ('tv_usec', c_long)]
lib = cdll.LoadLibrary("libusb-1.0.so")
lib.libusb_open_device_with_vid_pid.restype = POINTER(LIBUSB_DEVICE_HANDLE)
lib.libusb_alloc_transfer.restype = POINTER(LIBUSB_TRANSFER)
def libusb_fill_interrupt_transfer(transfer, dev_handle, endpoint, buffer, length, callback, user_data, timeout):
transfer[0].dev_handle = dev_handle
transfer[0].endpoint = chr(endpoint)
transfer[0].type = chr(LIBUSB_TRANSFER_TYPE_INTERRUPT)
transfer[0].timeout = timeout
transfer[0].buffer = buffer
transfer[0].length = length
transfer[0].user_data = user_data
transfer[0].callback = LIBUSB_TRANSFER_CB_FN(callback)
def cb_transfer(transfer):
print "Transfer status %d" % transfer.status
if __name__ == "__main__":
context = POINTER(LIBUSB_CONTEXT)()
lib.libusb_init(None)
transfer = lib.libusb_alloc_transfer(0)
handle = lib.libusb_open_device_with_vid_pid(None, VENDOR_ID, PRODUCT_ID)
size = _USBLCD_MAX_DATA_LEN
buffer = c_char_p(size)
libusb_fill_interrupt_transfer(transfer, handle, LIBUSB_ENDPOINT_IN + 1, buffer, size, cb_transfer, None, 0)
r = lib.libusb_submit_transfer(transfer) # This is returning -2, should be => 0.
if r < 0:
print "libusb_submit_transfer failed", r
while r >= 0:
print "Poll before"
tv = TIMEVAL(1, 0)
r = lib.libusb_handle_events_timeout(None, byref(tv))
print "Poll after", r
Eh bien, en Python, vous n'avez pas besoin de déclarer les types. Vous pouvez assigner dynamiquement des valeurs de différents types à des variables. Cependant, ctypes doit connaître certaines informations sur les types. Le type de retour de lib.libusb_alloc_transfer est déclaré ici: lib.libusb_alloc_transfer.restype = POINTER (LIBUSB_TRANSFER) – Scott