Merge pull request #262 from antoinevg/antoinevg/fix-acm-serial

examples: fix acm_serial example

luna/gateware/usb/devices/acm.py

@@ -45,7 +45,7 @@ def elaborate(self, platform):
  # SET_LINE_CODING: The host attempts to tell us how it wants serial data
  # encoding. Since we output a stream, we'll ignore the actual line coding.
  with m.Case(self.SET_LINE_CODING):
- 
+
  # Drive interface outputs for this request
  m.d.comb += interface.claim.eq(1)
 
@@ -56,7 +56,7 @@ def elaborate(self, platform):
  # ... and accept whatever the request was.
  with m.If(interface.status_requested):
  m.d.comb += self.send_zlp()
- 
+
  return m
 
 
@@ -102,7 +102,7 @@ class USBSerialDevice(Elaboratable):
  def __init__(self, *, bus, idVendor, idProduct,
  manufacturer_string="LUNA",
  product_string="USB-to-serial",
- serial_number=None, max_packet_size=64):
+ serial_number="", max_packet_size=64):
 
  self._bus = bus
  self._idVendor = idVendor
@@ -239,4 +239,3 @@ def elaborate(self, platform):
  ]
 
  return m
-