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Merge pull request #337 from paulusmack/fixes

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ECP5: Adjust PLL constants so the PLL lock indication works
This commit is contained in:
Michael Neuling
2021-10-25 16:49:19 +11:00
committed by GitHub
parent 8a030502a2 d458b5845c
commit 7fa7b45faa
1 changed files with 19 additions and 10 deletions
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29
fpga/clk_gen_ecp5.vhd
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@@ -82,33 +82,42 @@ architecture bypass of clock_generator is
CLKINTFB : out std_logic );
end component;
signal clkos : std_ulogic;
signal clkop : std_logic;
signal lock : std_logic;
-- PLL constants based on prjtrellis example
constant PLL_IN : natural := 2000000;
constant PLL_OUT : natural := 600000000;
-- PLL constants
-- According to the datasheet, PLL_IN needs to be between 10 and 400 MHz
-- PLL_OUT needs to be between 400 and 800 MHz
-- PLL_IN is chosen based on 12 and 48 MHz being common values
-- for the reference clock.
constant PLL_IN : natural := 12000000;
constant PLL_OUT : natural := 480000000;
-- Configration for ECP5 PLL
constant PLL_CLKOP_DIV : natural := PLL_OUT/CLK_OUTPUT_HZ;
constant PLL_CLKFB_DIV : natural := CLK_OUTPUT_HZ/PLL_IN;
constant PLL_CLKOS_DIV : natural := 2;
constant PLL_CLKFB_DIV : natural := PLL_OUT/PLL_CLKOS_DIV/PLL_IN;
constant PLL_CLKI_DIV : natural := CLK_INPUT_HZ/PLL_IN;
begin
pll_clk_out <= clkop;
pll_locked_out <= not lock; -- FIXME: EHXPLLL lock signal active low?!?
pll_locked_out <= lock;
clkgen: EHXPLLL
generic map(
CLKOP_CPHASE => 11, -- FIXME: Copied from prjtrells.
CLKOP_DIV => PLL_CLKOP_DIV,
CLKOS_ENABLE => "ENABLED",
CLKOS_DIV => PLL_CLKOS_DIV,
CLKFB_DIV => PLL_CLKFB_DIV,
CLKI_DIV => PLL_CLKI_DIV
CLKI_DIV => PLL_CLKI_DIV,
FEEDBK_PATH => "CLKOS"
)
port map (
CLKI => ext_clk,
CLKOP => clkop,
CLKFB => clkop,
CLKOS => clkos,
CLKFB => clkos,
LOCK => lock,
RST => pll_rst_in,
PHASESEL1 => '0',
@@ -118,8 +127,8 @@ begin
PHASELOADREG => '0',
STDBY => '0',
PLLWAKESYNC => '0',
ENCLKOP => '0',
ENCLKOS => '0',
ENCLKOP => '1',
ENCLKOS => '1',
ENCLKOS2 => '0',
ENCLKOS3 => '0'
);