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Feat cdc python #1

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fd786a5
chore: add premlinenary CDC interfaces
Apr 25, 2023
20ccc8b
usbd: Add cdc example and a basic read function.
hoihu Jun 8, 2023
9244f23
changed EP_OUT_FLAG to the new EP_IN_FLAG
linted Jul 14, 2023
e255093
Fixed a ustruct.pack issue causing the control interface to missrepor…
linted Jul 16, 2023
f63af44
changed the recv methods to actually be able to get messages from the…
linted Jul 23, 2023
586b054
Added check to ensure that read couldn't start before we received our…
linted Jul 25, 2023
f55fba4
Merge branch 'feat-cdc-python' into feat-cdc-python
linted Jul 28, 2023
e28c943
added check to ensure usb is setup before trying to send a message
linted Aug 3, 2023
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18 changes: 11 additions & 7 deletions micropython/usbd/cdc.py
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Original file line number Diff line number Diff line change
Expand Up @@ -44,13 +44,14 @@ class CDCControlInterface(USBInterface):
def __init__(self, interface_str):
super().__init__(_CDC_ITF_CONTROL_CLASS, _CDC_ITF_CONTROL_SUBCLASS,
_CDC_ITF_CONTROL_PROT)
self.ep_in = None

def get_itf_descriptor(self, num_eps, itf_idx, str_idx):
# CDC needs a Interface Association Descriptor (IAD)
# first interface is zero, two interfaces in total
desc = ustruct.pack("<BBBBBBBB", 8, _ITF_ASSOCIATION_DESC_TYPE, itf_idx, 2,
_CDC_ITF_CONTROL_CLASS, _CDC_ITF_CONTROL_SUBCLASS,
_CDC_ITF_CONTROL_PROT, 0) # "IAD"
_CDC_ITF_CONTROL_PROT, 4) # "IAD"
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As I understand, this is an index to a string descriptor describing the function. Do we have a string descriptor for that? Otherwise this value is 0.

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I honestly don't remember why I made it 4, just that it worked.


itf, strs = super().get_itf_descriptor(num_eps, itf_idx, str_idx)
desc += itf
Expand All @@ -59,12 +60,13 @@ def get_itf_descriptor(self, num_eps, itf_idx, str_idx):
desc += ustruct.pack("<BBBH", 5, _CS_DESC_TYPE, 0, 0x0120) # "Header"
desc += ustruct.pack("<BBBBB", 5, _CS_DESC_TYPE, 1, 0, 1) # "Call Management"
desc += ustruct.pack("<BBBB", 4, _CS_DESC_TYPE, 2, 2) # "Abstract Control"
desc += ustruct.pack("<BBBH", 5, _CS_DESC_TYPE, 6, itf_idx, 1) # "Union"
desc += ustruct.pack("<BBBBB", 5, _CS_DESC_TYPE, 6, itf_idx, itf_idx+1) # "Union"
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right, I corrected the itf_idx+1 already, but missed the struct pack pattern.

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This was the big problem that fixed most things. It took me a while to realize it as well.

return desc, strs

def get_endpoint_descriptors(self, ep_addr, str_idx):
self.ep_in = endpoint_descriptor((ep_addr + 1) | EP_IN_FLAG, "interrupt", 8, 16)
return (self.ep_in, [], ((ep_addr+1) | EP_IN_FLAG,))
self.ep_in = (ep_addr) | EP_IN_FLAG
desc = endpoint_descriptor(self.ep_in, "interrupt", 8, 16)
return (desc, [], (self.ep_in,))
Comment on lines +71 to +73
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Yes that looks good



class CDCDataInterface(USBInterface):
Expand All @@ -78,18 +80,20 @@ def __init__(self, interface_str, timeout=1):
self.rx_done = False
self.rx_nbytes = 0
self.timeout = timeout
self.ep_in = None
self.ep_out = None

def get_endpoint_descriptors(self, ep_addr, str_idx):
# XXX OUT = 0x00 but is defined as 0x80?
self.ep_in = (ep_addr + 2) | EP_IN_FLAG
self.ep_out = (ep_addr + 2) & ~EP_IN_FLAG
self.ep_in = (ep_addr) | EP_IN_FLAG
self.ep_out = (ep_addr) & ~EP_IN_FLAG
# one IN / OUT Endpoint
e_out = endpoint_descriptor(self.ep_out, "bulk", 64, 0)
e_in = endpoint_descriptor(self.ep_in, "bulk", 64, 0)
return (e_out + e_in, [], (self.ep_out, self.ep_in))

def write(self, data):
super().submit_xfer(self.ep_in, data)
self.submit_xfer(self.ep_in, data)

def read(self, nbytes=0):
# XXX PoC.. When returning, it should probably
Expand Down