Subversion Repositories simpcon

--
--	scio_min.vhd
--
--	io devices for minimal configuration
--	only counter, wd and serial line, alle io pins are tri statet
--
--
--	io address mapping:
--
--	IO Base is 0xffffff80 for 'fast' constants (bipush)
--
--		0x00 0-3		system clock counter, us counter, timer int, wd bit
--		0x10 0-1		uart (download)
--
--	status word in uarts:
--		0	uart transmit data register empty
--		1	uart read data register full
--
--
--	todo:
--
--
--	2003-07-09	created
--	2005-08-27	ignore ncts on uart
--	2005-11-30	changed to SimpCon
--	2007-03-17	use records
--
--
 
 
Library IEEE;
use IEEE.std_logic_1164.all;
use ieee.numeric_std.all;
 
use work.jop_types.all;
use work.sc_pack.all;
use work.jop_config.all;
 
entity scio is
generic (cpu_id : integer := 0);
port (
	clk		: in std_logic;
	reset	: in std_logic;
 
--
--	SimpCon IO interface
--
	sc_io_out		: in sc_io_out_type;
	sc_io_in		: out sc_in_type;
 
--
--	Interrupts from IO devices
--
	irq_in			: out irq_in_type;
	exc_req			: in exception_type;
 
-- CMP
 
	sync_out : in sync_out_type := NO_SYNC;
	sync_in	 : out sync_in_type;
 
-- serial interface
 
	txd			: out std_logic;
	rxd			: in std_logic;
	ncts		: in std_logic;
	nrts		: out std_logic;
 
-- watch dog
 
	wd			: out std_logic;
 
-- core i/o pins
	l			: inout std_logic_vector(20 downto 1);
	r			: inout std_logic_vector(20 downto 1);
	t			: inout std_logic_vector(6 downto 1);
	b			: inout std_logic_vector(10 downto 1)
);
end scio;
 
 
architecture rtl of scio is
 
	constant SLAVE_CNT : integer := 3;
	-- SLAVE_CNT <= 2**DECODE_BITS
	-- take care of USB address 0x20!
	constant DECODE_BITS : integer := 2;
	-- number of bits that can be used inside the slave
	constant SLAVE_ADDR_BITS : integer := 4;
 
	type slave_bit is array(0 to SLAVE_CNT-1) of std_logic;
	signal sc_rd, sc_wr		: slave_bit;
 
	type slave_dout is array(0 to SLAVE_CNT-1) of std_logic_vector(31 downto 0);
	signal sc_dout			: slave_dout;
 
	type slave_rdy_cnt is array(0 to SLAVE_CNT-1) of unsigned(1 downto 0);
	signal sc_rdy_cnt		: slave_rdy_cnt;
 
	signal sel, sel_reg		: integer range 0 to 2**DECODE_BITS-1;
 
begin
 
--
--	unused and input pins tri state
--
	l <= (others => 'Z');
	r <= (others => 'Z');
	t <= (others => 'Z');
	b <= (others => 'Z');
 
	assert SLAVE_CNT <= 2**DECODE_BITS report "Wrong constant in scio";
 
	sel <= to_integer(unsigned(sc_io_out.address(SLAVE_ADDR_BITS+DECODE_BITS-1 downto SLAVE_ADDR_BITS)));
 
	-- What happens when sel_reg > SLAVE_CNT-1??
	sc_io_in.rd_data <= sc_dout(sel_reg);
	sc_io_in.rdy_cnt <= sc_rdy_cnt(sel_reg);
 
	-- default for unused USB device
	sc_dout(2) <= (others => '0');
	sc_rdy_cnt(2) <= (others => '0');
 
	--
	-- Connect SLAVE_CNT simple test slaves
	--
	gsl: for i in 0 to SLAVE_CNT-1 generate
 
		sc_rd(i) <= sc_io_out.rd when i=sel else '0';
		sc_wr(i) <= sc_io_out.wr when i=sel else '0';
 
	end generate;
 
	--
	--	Register read mux selector
	--
	process(clk, reset)
	begin
		if (reset='1') then
			sel_reg <= 0;
		elsif rising_edge(clk) then
			if sc_io_out.rd='1' then
				sel_reg <= sel;
			end if;
		end if;
	end process;
 
	cmp_sys: entity work.sc_sys generic map (
			addr_bits => SLAVE_ADDR_BITS,
			clk_freq => clk_freq,
			cpu_id => cpu_id
		)
		port map(
			clk => clk,
			reset => reset,
 
			address => sc_io_out.address(SLAVE_ADDR_BITS-1 downto 0),
			wr_data => sc_io_out.wr_data,
			rd => sc_rd(0),
			wr => sc_wr(0),
			rd_data => sc_dout(0),
			rdy_cnt => sc_rdy_cnt(0),
 
			irq_in => irq_in,
			exc_req => exc_req,
 
			sync_out => sync_out,
			sync_in => sync_in,
 
			wd => wd
		);
 
	cmp_ua: entity work.sc_uart generic map (
			addr_bits => SLAVE_ADDR_BITS,
			clk_freq => clk_freq,
			baud_rate => 115200,
			txf_depth => 2,
			txf_thres => 1,
			rxf_depth => 2,
			rxf_thres => 1
		)
		port map(
			clk => clk,
			reset => reset,
 
			address => sc_io_out.address(SLAVE_ADDR_BITS-1 downto 0),
			wr_data => sc_io_out.wr_data,
			rd => sc_rd(1),
			wr => sc_wr(1),
			rd_data => sc_dout(1),
			rdy_cnt => sc_rdy_cnt(1),
 
			txd	 => txd,
			rxd	 => rxd,
			ncts => '0',
			nrts => nrts
	);
 
end rtl;