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neorv32/rtl/core/neorv32_neoled.vhd

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-- #################################################################################################
-- # << NEORV32 - Smart LED (WS2811/WS2812) Interface (NEOLED) >> #
-- # ********************************************************************************************* #
-- # Hardware interface for direct control of "smart LEDs" using an asynchronous serial data #
-- # line. Compatible with the WS2811 and WS2812 LEDs. #
-- # #
-- # NeoPixel-compatible, RGB (24-bit) and RGBW (32-bit) modes supported (in "parallel") #
-- # (TM) "NeoPixel" is a trademark of Adafruit Industries. #
-- # #
-- # The interface uses a programmable carrier frequency (800 KHz for the WS2812 LEDs) #
-- # configurable via the control register's clock prescaler bits (ctrl_clksel*_c) and the period #
-- # length configuration bits (ctrl_t_tot_*_c). "high-times" for sending a ZERO or a ONE bit are #
-- # configured using the ctrl_t_0h_*_c and ctrl_t_1h_*_c bits, respectively. 32-bit transfers #
-- # (for RGBW modules) and 24-bit transfers (for RGB modules) are supported via ctrl_mode__c. #
-- # #
-- # The device features a TX buffer (FIFO) with <FIFO_DEPTH> entries with configurable interrupt. #
-- # ********************************************************************************************* #
-- # BSD 3-Clause License #
-- # #
-- # The NEORV32 RISC-V Processor, https://github.com/stnolting/neorv32 #
-- # Copyright (c) 2024, Stephan Nolting. All rights reserved. #
-- # #
-- # Redistribution and use in source and binary forms, with or without modification, are #
-- # permitted provided that the following conditions are met: #
-- # #
-- # 1. Redistributions of source code must retain the above copyright notice, this list of #
-- # conditions and the following disclaimer. #
-- # #
-- # 2. Redistributions in binary form must reproduce the above copyright notice, this list of #
-- # conditions and the following disclaimer in the documentation and/or other materials #
-- # provided with the distribution. #
-- # #
-- # 3. Neither the name of the copyright holder nor the names of its contributors may be used to #
-- # endorse or promote products derived from this software without specific prior written #
-- # permission. #
-- # #
-- # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS #
-- # OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF #
-- # MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE #
-- # COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, #
-- # EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE #
-- # GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED #
-- # AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING #
-- # NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED #
-- # OF THE POSSIBILITY OF SUCH DAMAGE. #
-- #################################################################################################
library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
library neorv32;
use neorv32.neorv32_package.all;
entity neorv32_neoled is
generic (
FIFO_DEPTH : natural range 1 to 2**15 -- NEOLED FIFO depth, has to be a power of two, min 1
);
port (
clk_i : in std_ulogic; -- global clock line
rstn_i : in std_ulogic; -- global reset line, low-active
bus_req_i : in bus_req_t; -- bus request
bus_rsp_o : out bus_rsp_t; -- bus response
clkgen_en_o : out std_ulogic; -- enable clock generator
clkgen_i : in std_ulogic_vector(7 downto 0);
irq_o : out std_ulogic; -- interrupt request
neoled_o : out std_ulogic -- serial async data line
);
end neorv32_neoled;
architecture neorv32_neoled_rtl of neorv32_neoled is
-- Control register bits --
constant ctrl_en_c : natural := 0; -- r/w: module enable
constant ctrl_mode_c : natural := 1; -- r/w: 0 = 24-bit RGB mode, 1 = 32-bit RGBW mode
constant ctrl_strobe_c : natural := 2; -- r/w: 0 = send normal data, 1 = send LED strobe command (RESET) on data write
--
constant ctrl_clksel0_c : natural := 3; -- r/w: prescaler select bit 0
constant ctrl_clksel1_c : natural := 4; -- r/w: prescaler select bit 1
constant ctrl_clksel2_c : natural := 5; -- r/w: prescaler select bit 2
--
constant ctrl_bufs_0_c : natural := 6; -- r/-: log2(FIFO_DEPTH) bit 0
constant ctrl_bufs_1_c : natural := 7; -- r/-: log2(FIFO_DEPTH) bit 1
constant ctrl_bufs_2_c : natural := 8; -- r/-: log2(FIFO_DEPTH) bit 2
constant ctrl_bufs_3_c : natural := 9; -- r/-: log2(FIFO_DEPTH) bit 3
--
constant ctrl_t_tot_0_c : natural := 10; -- r/w: pulse-clock ticks per total period bit 0
constant ctrl_t_tot_1_c : natural := 11; -- r/w: pulse-clock ticks per total period bit 1
constant ctrl_t_tot_2_c : natural := 12; -- r/w: pulse-clock ticks per total period bit 2
constant ctrl_t_tot_3_c : natural := 13; -- r/w: pulse-clock ticks per total period bit 3
constant ctrl_t_tot_4_c : natural := 14; -- r/w: pulse-clock ticks per total period bit 4
--
constant ctrl_t_0h_0_c : natural := 15; -- r/w: pulse-clock ticks per ZERO high-time bit 0
constant ctrl_t_0h_1_c : natural := 16; -- r/w: pulse-clock ticks per ZERO high-time bit 1
constant ctrl_t_0h_2_c : natural := 17; -- r/w: pulse-clock ticks per ZERO high-time bit 2
constant ctrl_t_0h_3_c : natural := 18; -- r/w: pulse-clock ticks per ZERO high-time bit 3
constant ctrl_t_0h_4_c : natural := 19; -- r/w: pulse-clock ticks per ZERO high-time bit 4
--
constant ctrl_t_1h_0_c : natural := 20; -- r/w: pulse-clock ticks per ONE high-time bit 0
constant ctrl_t_1h_1_c : natural := 21; -- r/w: pulse-clock ticks per ONE high-time bit 1
constant ctrl_t_1h_2_c : natural := 22; -- r/w: pulse-clock ticks per ONE high-time bit 2
constant ctrl_t_1h_3_c : natural := 23; -- r/w: pulse-clock ticks per ONE high-time bit 3
constant ctrl_t_1h_4_c : natural := 24; -- r/w: pulse-clock ticks per ONE high-time bit 4
--
constant ctrl_irq_conf_c : natural := 27; -- r/w: interrupt condition: 0=IRQ when buffer less than half full, 1=IRQ when buffer is empty
constant ctrl_tx_empty_c : natural := 28; -- r/-: TX FIFO is empty
constant ctrl_tx_half_c : natural := 29; -- r/-: TX FIFO is at least half-full
constant ctrl_tx_full_c : natural := 30; -- r/-: TX FIFO is full
constant ctrl_tx_busy_c : natural := 31; -- r/-: serial TX engine busy when set
-- control register --
type ctrl_t is record
enable : std_ulogic;
mode : std_ulogic;
strobe : std_ulogic;
clk_prsc : std_ulogic_vector(2 downto 0);
irq_conf : std_ulogic;
t_total : std_ulogic_vector(4 downto 0);
t0_high : std_ulogic_vector(4 downto 0);
t1_high : std_ulogic_vector(4 downto 0);
end record;
signal ctrl : ctrl_t;
-- transmission buffer --
type tx_fifo_t is record
we : std_ulogic; -- write enable
re : std_ulogic; -- read enable
clear : std_ulogic; -- sync reset, high-active
wdata : std_ulogic_vector(31+2 downto 0); -- write data (excluding mode)
rdata : std_ulogic_vector(31+2 downto 0); -- read data (including mode)
avail : std_ulogic; -- data available?
free : std_ulogic; -- free entry available?
half : std_ulogic; -- half full
end record;
signal tx_fifo : tx_fifo_t;
-- serial transmission engine --
type serial_t is record
-- state control --
state : std_ulogic_vector(2 downto 0);
mode : std_ulogic;
done : std_ulogic;
busy : std_ulogic;
bit_cnt : std_ulogic_vector(5 downto 0);
-- shift register --
sreg : std_ulogic_vector(31 downto 0);
next_bit : std_ulogic; -- next bit to send
-- pulse generator --
pulse_clk : std_ulogic; -- pulse cycle "clock"
pulse_cnt : std_ulogic_vector(4 downto 0);
t_high : std_ulogic_vector(4 downto 0);
strobe_cnt : std_ulogic_vector(6 downto 0);
end record;
signal serial : serial_t;
begin
-- Bus Access -----------------------------------------------------------------------------
-- -------------------------------------------------------------------------------------------
bus_access: process(rstn_i, clk_i)
begin
if (rstn_i = '0') then
ctrl.enable <= '0';
ctrl.mode <= '0';
ctrl.strobe <= '0';
ctrl.clk_prsc <= (others => '0');
ctrl.irq_conf <= '0';
ctrl.t_total <= (others => '0');
ctrl.t0_high <= (others => '0');
ctrl.t1_high <= (others => '0');
--
bus_rsp_o.ack <= '0';
bus_rsp_o.err <= '0';
bus_rsp_o.data <= (others => '0');
elsif rising_edge(clk_i) then
-- bus handshake --
bus_rsp_o.ack <= bus_req_i.stb;
bus_rsp_o.err <= '0';
bus_rsp_o.data <= (others => '0');
if (bus_req_i.stb = '1') then
-- write access --
if (bus_req_i.rw = '1') then
if (bus_req_i.addr(2) = '0') then
ctrl.enable <= bus_req_i.data(ctrl_en_c);
ctrl.mode <= bus_req_i.data(ctrl_mode_c);
ctrl.strobe <= bus_req_i.data(ctrl_strobe_c);
ctrl.clk_prsc <= bus_req_i.data(ctrl_clksel2_c downto ctrl_clksel0_c);
ctrl.irq_conf <= bus_req_i.data(ctrl_irq_conf_c);
ctrl.t_total <= bus_req_i.data(ctrl_t_tot_4_c downto ctrl_t_tot_0_c);
ctrl.t0_high <= bus_req_i.data(ctrl_t_0h_4_c downto ctrl_t_0h_0_c);
ctrl.t1_high <= bus_req_i.data(ctrl_t_1h_4_c downto ctrl_t_1h_0_c);
end if;
-- read access --
else
bus_rsp_o.data(ctrl_en_c) <= ctrl.enable;
bus_rsp_o.data(ctrl_mode_c) <= ctrl.mode;
bus_rsp_o.data(ctrl_strobe_c) <= ctrl.strobe;
bus_rsp_o.data(ctrl_clksel2_c downto ctrl_clksel0_c) <= ctrl.clk_prsc;
bus_rsp_o.data(ctrl_irq_conf_c) <= ctrl.irq_conf or bool_to_ulogic_f(boolean(FIFO_DEPTH = 1)); -- tie to one if FIFO_DEPTH is 1
bus_rsp_o.data(ctrl_bufs_3_c downto ctrl_bufs_0_c) <= std_ulogic_vector(to_unsigned(index_size_f(FIFO_DEPTH), 4));
bus_rsp_o.data(ctrl_t_tot_4_c downto ctrl_t_tot_0_c) <= ctrl.t_total;
bus_rsp_o.data(ctrl_t_0h_4_c downto ctrl_t_0h_0_c) <= ctrl.t0_high;
bus_rsp_o.data(ctrl_t_1h_4_c downto ctrl_t_1h_0_c) <= ctrl.t1_high;
--
bus_rsp_o.data(ctrl_tx_empty_c) <= not tx_fifo.avail;
bus_rsp_o.data(ctrl_tx_half_c) <= tx_fifo.half;
bus_rsp_o.data(ctrl_tx_full_c) <= not tx_fifo.free;
bus_rsp_o.data(ctrl_tx_busy_c) <= serial.busy;
end if;
end if;
end if;
end process bus_access;
-- enable external clock generator --
clkgen_en_o <= ctrl.enable;
-- TX Buffer (FIFO) -----------------------------------------------------------------------
-- -------------------------------------------------------------------------------------------
data_buffer: entity neorv32.neorv32_fifo
generic map (
FIFO_DEPTH => FIFO_DEPTH, -- number of fifo entries; has to be a power of two; min 1
FIFO_WIDTH => 32+2, -- size of data elements in fifo
FIFO_RSYNC => true, -- sync read
FIFO_SAFE => true, -- safe access
FULL_RESET => false -- no HW reset, try to infer BRAM
)
port map (
-- control --
clk_i => clk_i, -- clock, rising edge
rstn_i => rstn_i, -- async reset, low-active
clear_i => tx_fifo.clear, -- sync reset, high-active
half_o => tx_fifo.half, -- FIFO is at least half full
-- write port --
wdata_i => tx_fifo.wdata, -- write data
we_i => tx_fifo.we, -- write enable
free_o => tx_fifo.free, -- at least one entry is free when set
-- read port --
re_i => tx_fifo.re, -- read enable
rdata_o => tx_fifo.rdata, -- read data
avail_o => tx_fifo.avail -- data available when set
);
tx_fifo.re <= '1' when (serial.state = "100") else '0';
tx_fifo.we <= '1' when (bus_req_i.stb = '1') and (bus_req_i.rw = '1') and (bus_req_i.addr(2) = '1') else '0';
tx_fifo.wdata <= ctrl.strobe & ctrl.mode & bus_req_i.data;
tx_fifo.clear <= not ctrl.enable;
-- IRQ generator --
irq_generator: process(rstn_i, clk_i)
begin
if (rstn_i = '0') then
irq_o <= '0';
elsif rising_edge(clk_i) then
irq_o <= ctrl.enable and (
((not ctrl.irq_conf) and (not tx_fifo.avail)) or -- fire IRQ if FIFO is empty
(( ctrl.irq_conf) and (not tx_fifo.half))); -- fire IRQ if FIFO is less than half full
end if;
end process irq_generator;
-- Serial TX Engine -----------------------------------------------------------------------
-- -------------------------------------------------------------------------------------------
serial_engine: process(rstn_i, clk_i)
begin
if (rstn_i = '0') then
serial.pulse_clk <= '0';
serial.done <= '0';
serial.state <= (others => '0');
serial.pulse_cnt <= (others => '0');
serial.strobe_cnt <= (others => '0');
serial.sreg <= (others => '0');
serial.mode <= '0';
serial.bit_cnt <= (others => '0');
serial.t_high <= (others => '0');
neoled_o <= '0';
elsif rising_edge(clk_i) then
-- clock generator --
serial.pulse_clk <= clkgen_i(to_integer(unsigned(ctrl.clk_prsc)));
-- defaults --
serial.done <= '0';
-- FSM --
serial.state(2) <= ctrl.enable;
case serial.state is
when "100" => -- IDLE: waiting for new TX data, prepare transmission
-- ------------------------------------------------------------
neoled_o <= '0';
serial.pulse_cnt <= (others => '0');
serial.strobe_cnt <= (others => '0');
serial.sreg <= tx_fifo.rdata(31 downto 0);
if (tx_fifo.rdata(32) = '0') then -- "RGB" mode
serial.mode <= '0';
serial.bit_cnt <= "011000"; -- total number of bits to send: 3x8=24
else -- "RGBW" mode
serial.mode <= '1';
serial.bit_cnt <= "100000"; -- total number of bits to send: 4x8=32
end if;
if (tx_fifo.avail = '1') then
if (tx_fifo.rdata(33) = '0') then -- send data
serial.state(1 downto 0) <= "01";
else -- send RESET command
serial.state(1 downto 0) <= "11";
end if;
end if;
when "101" => -- GETBIT: get next TX bit
-- ------------------------------------------------------------
serial.sreg <= serial.sreg(serial.sreg'left-1 downto 0) & '0'; -- shift left by one position (MSB-first)
serial.bit_cnt <= std_ulogic_vector(unsigned(serial.bit_cnt) - 1);
serial.pulse_cnt <= (others => '0');
if (serial.next_bit = '0') then -- send zero-bit
serial.t_high <= ctrl.t0_high;
else -- send one-bit
serial.t_high <= ctrl.t1_high;
end if;
if (serial.bit_cnt = "000000") then -- all done?
neoled_o <= '0';
serial.done <= '1'; -- done sending data
serial.state(1 downto 0) <= "00";
else -- send current data MSB
neoled_o <= '1';
serial.state(1 downto 0) <= "10"; -- transmit single pulse
end if;
when "110" => -- PULSE: send pulse with specific duty cycle
-- ------------------------------------------------------------
-- total pulse length = ctrl.t_total
-- pulse high time = serial.t_high
if (serial.pulse_clk = '1') then
serial.pulse_cnt <= std_ulogic_vector(unsigned(serial.pulse_cnt) + 1);
-- T_high reached? --
if (serial.pulse_cnt = serial.t_high) then
neoled_o <= '0';
end if;
-- T_total reached? --
if (serial.pulse_cnt = ctrl.t_total) then
serial.state(1 downto 0) <= "01"; -- get next bit to send
end if;
end if;
when "111" => -- STROBE: strobe LED data ("RESET" command)
-- ------------------------------------------------------------
-- wait for 127 * ctrl.t_total to ensure RESET
if (serial.pulse_clk = '1') then
-- T_total reached? --
if (serial.pulse_cnt = ctrl.t_total) then
serial.pulse_cnt <= (others => '0');
serial.strobe_cnt <= std_ulogic_vector(unsigned(serial.strobe_cnt) + 1);
else
serial.pulse_cnt <= std_ulogic_vector(unsigned(serial.pulse_cnt) + 1);
end if;
end if;
-- number of LOW periods reached for RESET? --
if (and_reduce_f(serial.strobe_cnt) = '1') then
serial.done <= '1'; -- done sending RESET
serial.state(1 downto 0) <= "00";
end if;
when others => -- "0--": disabled
-- ------------------------------------------------------------
serial.state(1 downto 0) <= "00";
end case;
end if;
end process serial_engine;
-- SREG's TX data: bit 23 for RGB mode (24-bit), bit 31 for RGBW mode (32-bit) --
serial.next_bit <= serial.sreg(23) when (serial.mode = '0') else serial.sreg(31);
-- TX engine status --
serial.busy <= '0' when (serial.state(1 downto 0) = "00") else '1';
end neorv32_neoled_rtl;
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