FullHD on Arty board using Litex

digilent_arty.py

# Copyright (c) 2024 Victor Suarez Rovere <suarezvictor@gmail.com>
# SPDX-License-Identifier: AGPL-3.0-only
# code portions from LiteX framework (C) Enjoy-Digital https://github.com/enjoy-digital/litex

import sys
import argparse

from migen import *
from litex.soc.cores.clock import *
from litex.soc.integration.builder import *
from litex.soc.integration.soc_core import *
from litex.build.generic_platform import *
from litex_boards.platforms import digilent_arty
from litex.soc.cores.video import VideoS7HDMIPHY as DVIPHY


class _CRG(Module):
    def __init__(self, platform, sys_clk_freq, video_clock):
        self.rst = Signal()
        self.clock_domains.cd_sys = ClockDomain()

        self.submodules.pll = pll = S7PLL(speedgrade=-1)
        rst    = ~platform.request("cpu_reset")
        self.comb += pll.reset.eq(rst | self.rst)
        pll.register_clkin(platform.request("clk100"), 100e6)
        pll.create_clkout(self.cd_sys, sys_clk_freq)

        self.clock_domains.cd_dvi   = ClockDomain()
        self.clock_domains.cd_dvi5x = ClockDomain()
        pll.create_clkout(self.cd_dvi,     video_clock)
        pll.create_clkout(self.cd_dvi5x, 5*video_clock)

        # Ignore sys_clk to pll.clkin path created by SoC's rst.
        platform.add_false_path_constraints(self.cd_sys.clk, pll.clkin)


def build_arty(args):
	platform = digilent_arty.Platform(variant="a7-35")

	sys_clk_freq = int(100e6)
	video_timings = "1920x1080@60Hz"; video_clock = 150e6
	soc = SoCCore(platform, sys_clk_freq, **soc_core_argdict(args))
	soc.submodules.crg = _CRG(platform, sys_clk_freq, video_clock)


	# Video -------------------------------------------------------------------------------------
	dvi_pins  = "45230167"
	pmod_dvi  = "pmodc"
	dvi_iostd = "TMDS_33"
	platform.add_extension([("dvi_out", 0,
                Subsignal("data0_p", Pins(f"{pmod_dvi}:{dvi_pins[0]}"), IOStandard(dvi_iostd)), #B0+
                Subsignal("data0_n", Pins(f"{pmod_dvi}:{dvi_pins[1]}"), IOStandard(dvi_iostd)), #B0-
                Subsignal("data1_p", Pins(f"{pmod_dvi}:{dvi_pins[2]}"), IOStandard(dvi_iostd)), #G1+
                Subsignal("data1_n", Pins(f"{pmod_dvi}:{dvi_pins[3]}"), IOStandard(dvi_iostd)), #G1-
                Subsignal("data2_p", Pins(f"{pmod_dvi}:{dvi_pins[4]}"), IOStandard(dvi_iostd)), #R2+
                Subsignal("data2_n", Pins(f"{pmod_dvi}:{dvi_pins[5]}"), IOStandard(dvi_iostd)), #R2-
                Subsignal("clk_p",   Pins(f"{pmod_dvi}:{dvi_pins[6]}"), IOStandard(dvi_iostd)),
                Subsignal("clk_n",   Pins(f"{pmod_dvi}:{dvi_pins[7]}"), IOStandard(dvi_iostd)))
	])
	video_clock_domain = "dvi"
	soc.submodules.videophy = DVIPHY(platform.request("dvi_out"), clock_domain=video_clock_domain)
	soc.add_video_terminal(phy=soc.videophy, timings=video_timings, clock_domain=video_clock_domain)

	return soc


def main():
	from litex.build.parser import LiteXArgumentParser
	parser = LiteXArgumentParser(platform=digilent_arty.Platform, description="LiteX SoC on Arty A7")
	args = parser.parse_args()
	soc = build_arty(args)

	builder = Builder(soc)
	builder.build()

if __name__ == "__main__":
	main()