litex/misoclib/com/uart/phy/serial.py

102 lines
2.5 KiB
Python
Raw Normal View History

from migen.fhdl.std import *
from migen.genlib.cdc import MultiReg
from migen.bank.description import *
from migen.flow.actor import Sink, Source
class UARTPHYSerialRX(Module):
def __init__(self, pads, tuning_word):
self.source = Source([("d", 8)])
###
uart_clk_rxen = Signal()
phase_accumulator_rx = Signal(32)
rx = Signal()
self.specials += MultiReg(pads.rx, rx)
rx_r = Signal()
rx_reg = Signal(8)
rx_bitcount = Signal(4)
rx_busy = Signal()
rx_done = self.source.stb
rx_data = self.source.d
self.sync += [
rx_done.eq(0),
rx_r.eq(rx),
If(~rx_busy,
If(~rx & rx_r, # look for start bit
rx_busy.eq(1),
rx_bitcount.eq(0),
)
).Else(
If(uart_clk_rxen,
rx_bitcount.eq(rx_bitcount + 1),
If(rx_bitcount == 0,
If(rx, # verify start bit
rx_busy.eq(0)
)
).Elif(rx_bitcount == 9,
rx_busy.eq(0),
If(rx, # verify stop bit
rx_data.eq(rx_reg),
rx_done.eq(1)
)
).Else(
rx_reg.eq(Cat(rx_reg[1:], rx))
)
)
)
]
self.sync += \
If(rx_busy,
Cat(phase_accumulator_rx, uart_clk_rxen).eq(phase_accumulator_rx + tuning_word)
).Else(
Cat(phase_accumulator_rx, uart_clk_rxen).eq(2**31)
)
class UARTPHYSerialTX(Module):
def __init__(self, pads, tuning_word):
self.sink = Sink([("d", 8)])
###
uart_clk_txen = Signal()
phase_accumulator_tx = Signal(32)
pads.tx.reset = 1
tx_reg = Signal(8)
tx_bitcount = Signal(4)
tx_busy = Signal()
self.sync += [
self.sink.ack.eq(0),
If(self.sink.stb & ~tx_busy & ~self.sink.ack,
tx_reg.eq(self.sink.d),
tx_bitcount.eq(0),
tx_busy.eq(1),
pads.tx.eq(0)
).Elif(uart_clk_txen & tx_busy,
tx_bitcount.eq(tx_bitcount + 1),
If(tx_bitcount == 8,
pads.tx.eq(1)
).Elif(tx_bitcount == 9,
pads.tx.eq(1),
tx_busy.eq(0),
self.sink.ack.eq(1),
).Else(
pads.tx.eq(tx_reg[0]),
tx_reg.eq(Cat(tx_reg[1:], 0))
)
)
]
self.sync += [
If(tx_busy,
Cat(phase_accumulator_tx, uart_clk_txen).eq(phase_accumulator_tx + tuning_word)
).Else(
Cat(phase_accumulator_tx, uart_clk_txen).eq(0)
)
]
class UARTPHYSerial(Module, AutoCSR):
def __init__(self, pads, clk_freq, baudrate=115200):
self._tuning_word = CSRStorage(32, reset=int((baudrate/clk_freq)*2**32))
self.submodules.tx = UARTPHYSerialTX(pads, self._tuning_word.storage)
self.submodules.rx = UARTPHYSerialRX(pads, self._tuning_word.storage)
self.sink, self.source = self.tx.sink, self.rx.source