#!/usr/bin/env python3
import unittest
from migen import *
[docs]class Raw(Instance.PreformattedParam):
def __init__(self, value):
self.value = value
[docs]class IoBuf(Module):
def __init__(self, usbp_pin, usbn_pin, usb_pullup_pin=None):
# tx/rx io interface
self.usb_tx_en = Signal()
self.usb_p_tx = Signal()
self.usb_n_tx = Signal()
self.usb_p_rx = Signal()
self.usb_n_rx = Signal()
self.usb_p_rx_io = Signal()
self.usb_n_rx_io = Signal()
usb_p_t = TSTriple()
usb_n_t = TSTriple()
self.specials += usb_p_t.get_tristate(usbp_pin)
self.specials += usb_n_t.get_tristate(usbn_pin)
self.usb_pullup = Signal()
if usb_pullup_pin is not None:
self.comb += [
usb_pullup_pin.eq(self.usb_pullup),
]
#######################################################################
#######################################################################
#### Mux the USB +/- pair with the TX and RX paths
#######################################################################
#######################################################################
usb_p_t_i_flop = Signal(3)
usb_n_t_i_flop = Signal(3)
self.sync += [
usb_p_t_i_flop.eq(Cat(usb_p_t.i, usb_p_t_i_flop[0], usb_p_t_i_flop[1])),
usb_n_t_i_flop.eq(Cat(usb_n_t.i, usb_n_t_i_flop[0], usb_n_t_i_flop[1])),
]
self.comb += [
If(self.usb_tx_en,
self.usb_p_rx.eq(0b1),
self.usb_n_rx.eq(0b0),
).Else(
self.usb_p_rx.eq(usb_p_t_i_flop[2]),
self.usb_n_rx.eq(usb_n_t_i_flop[2]),
),
usb_p_t.oe.eq(self.usb_tx_en),
usb_n_t.oe.eq(self.usb_tx_en),
usb_p_t.o.eq(self.usb_p_tx),
usb_n_t.o.eq(self.usb_n_tx),
]
[docs]class FakeIoBuf(Module):
def __init__(self):
self.usb_pullup = Signal()
self.usb_p = Signal()
self.usb_n = Signal()
self.usb_tx_en = Signal()
self.usb_p_tx = Signal()
self.usb_n_tx = Signal()
self.usb_p_rx = Signal()
self.usb_n_rx = Signal()
self.usb_p_rx_io = Signal()
self.usb_n_rx_io = Signal()
self.comb += [
If(self.usb_tx_en,
self.usb_p_rx.eq(0b1),
self.usb_n_rx.eq(0b0)
).Else(
self.usb_p_rx.eq(self.usb_p_rx_io),
self.usb_n_rx.eq(self.usb_n_rx_io)
),
]
self.comb += [
If(self.usb_tx_en,
self.usb_p.eq(self.usb_p_tx),
self.usb_n.eq(self.usb_n_tx),
).Else(
self.usb_p.eq(self.usb_p_rx),
self.usb_n.eq(self.usb_n_rx),
),
]
[docs] def recv(self, v):
tx_en = yield self.usb_tx_en
assert not tx_en, "Currently transmitting!"
if v == '0' or v == '_':
# SE0 - both lines pulled low
yield self.usb_p_rx_io.eq(0)
yield self.usb_n_rx_io.eq(0)
elif v == '1':
# SE1 - illegal, should never occur
yield self.usb_p_rx_io.eq(1)
yield self.usb_n_rx_io.eq(1)
elif v == '-' or v == 'I':
# Idle
yield self.usb_p_rx_io.eq(1)
yield self.usb_n_rx_io.eq(0)
elif v == 'J':
yield self.usb_p_rx_io.eq(1)
yield self.usb_n_rx_io.eq(0)
elif v == 'K':
yield self.usb_p_rx_io.eq(0)
yield self.usb_n_rx_io.eq(1)
else:
assert False, "Unknown value: %s" % v
[docs] def current(self):
usb_p = yield self.usb_p
usb_n = yield self.usb_n
values = (usb_p, usb_n)
if values == (0, 0):
return '_'
elif values == (1, 1):
return '1'
elif values == (1, 0):
return 'J'
elif values == (0, 1):
return 'K'
else:
assert False, values