--COMMAND STRUCTURE OF SERAL USB PROTOCOL
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--COMMAND STRUCTURE OF SERAL USB PROTOCOL
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-- MSBYTE LSBYTE
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-- MSBYTE LSBYTE
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-- DATA CODE
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-- DATA CODE
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--Dongle internal command codes
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--Dongle internal command codes
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-- 0x-- 0xC5 --Get Status data is don't care (must return) 0x3210 (3 is the MSNibble)
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-- 0x-- 0xC5 --Get Status data is don't care (must return) 0x3210 (3 is the MSNibble)
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-- 0xNN 0xCD --Get Data from flash (performs read from current address) NN count of words auto increment address
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-- 0xNN 0xCD --Get Data from flash (performs read from current address) NN count of words auto increment address
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-- 0xAA 0xA0 --Addr LSByte write
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-- 0xAA 0xA0 --Addr LSByte write
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-- 0xAA 0xA1 --Addr Byte write
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-- 0xAA 0xA1 --Addr Byte write
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-- 0xAA 0xA2 --Addr MSByte write
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-- 0xAA 0xA2 --Addr MSByte write
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-- 0x-- 0x3F --NOP
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-- 0x-- 0x3F --NOP
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--Flash operations codes
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--Flash operations codes
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-- 0xNN 0xE8 --Write to buffer returns extended satus NN is word count for USB machine
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-- 0xNN 0xE8 --Write to buffer returns extended satus NN is word count for USB machine
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-- 0x-- 0xD0 -- 0xD0 is flash confirm command
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-- 0x-- 0xD0 -- 0xD0 is flash confirm command
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--write buffer sequence
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--write buffer sequence
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-- ??? -- set address if needed
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-- ??? -- set address if needed
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-- 0xNN 0xE8 --Write to buffer returns extended satus NN is word count for USB machine
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-- 0xNN 0xE8 --Write to buffer returns extended satus NN is word count for USB machine
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-- 0x-- 0xNN --0xNN is word count for flash ges directly to flash and is wordCount - 1
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-- 0x-- 0xNN --0xNN is word count for flash ges directly to flash and is wordCount - 1
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-- 0xDD 0xDD --N+1 times data expected 0xF + 1 is the maximum
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-- 0xDD 0xDD --N+1 times data expected 0xF + 1 is the maximum
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-- ...
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-- ...
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-- 0x-- 0xD0 -- 0xD0 is flash confirm command
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-- 0x-- 0xD0 -- 0xD0 is flash confirm command
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library IEEE;
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library IEEE;
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use IEEE.std_logic_1164.all;
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use IEEE.std_logic_1164.all;
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use IEEE.std_logic_unsigned.all;
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use IEEE.std_logic_unsigned.all;
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use IEEE.std_logic_arith.all;
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use IEEE.std_logic_arith.all;
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entity usb2mem is
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entity usb2mem is
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port (
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port (
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clk25 : in std_logic;
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clk25 : in std_logic;
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reset_n : in std_logic;
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reset_n : in std_logic;
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dongle_ver: in std_logic_vector(15 downto 0);
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dongle_ver: in std_logic_vector(15 downto 0);
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-- mem Bus
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-- mem Bus
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mem_busy_n : in std_logic;
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mem_busy_n : in std_logic;
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mem_idle : out std_logic; -- '1' if controller is idle (flash is safe for LPC reads)
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mem_idle : out std_logic; -- '1' if controller is idle (flash is safe for LPC reads)
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mem_addr : out std_logic_vector(23 downto 0);
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mem_addr : out std_logic_vector(23 downto 0);
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mem_do : out std_logic_vector(15 downto 0);
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mem_do : out std_logic_vector(15 downto 0);
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mem_di : in std_logic_vector(15 downto 0);
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mem_di : in std_logic_vector(15 downto 0);
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mem_wr : out std_logic;
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mem_wr : out std_logic;
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mem_val : out std_logic;
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mem_val : out std_logic;
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mem_ack : in std_logic;
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mem_ack : in std_logic;
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mem_cmd : out std_logic;
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mem_cmd : out std_logic;
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-- USB port
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-- USB port
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usb_mode_en: in std_logic; -- enable this block
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usb_mode_en: in std_logic; -- enable this block
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usb_rd_n : out std_logic; -- enables out data if low (next byte detected by edge / in usb chip)
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usb_rd_n : out std_logic; -- enables out data if low (next byte detected by edge / in usb chip)
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usb_wr : out std_logic; -- write performed on edge \ of signal
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usb_wr : out std_logic; -- write performed on edge \ of signal
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usb_txe_n : in std_logic; -- tx fifo empty (redy for new data if low)
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usb_txe_n : in std_logic; -- tx fifo empty (redy for new data if low)
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usb_rxf_n : in std_logic; -- rx fifo empty (data redy if low)
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usb_rxf_n : in std_logic; -- rx fifo empty (data redy if low)
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usb_bd : inout std_logic_vector(7 downto 0) --bus data
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usb_bd : inout std_logic_vector(7 downto 0) --bus data
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);
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);
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end usb2mem;
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end usb2mem;
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architecture RTL of usb2mem is
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architecture RTL of usb2mem is
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type state_type is (RESETs,RXCMD0s,RXCMD1s,DECODEs,INTERNs,VCIRDs,VCIWRs,TXCMD0s,TXCMD1s,STS_WAITs);
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type state_type is (RESETs,RXCMD0s,RXCMD1s,DECODEs,INTERNs,VCIRDs,VCIWRs,TXCMD0s,TXCMD1s,STS_WAITs);
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signal CS : state_type;
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signal CS : state_type;
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signal data_reg_i : std_logic_vector(15 downto 0);
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signal data_reg_i : std_logic_vector(15 downto 0);
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signal data_reg_o : std_logic_vector(15 downto 0);
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signal data_reg_o : std_logic_vector(15 downto 0);
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signal data_oe : std_logic; -- rx fifo empty (data redy if low)
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signal data_oe : std_logic; -- rx fifo empty (data redy if low)
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signal usb_wr_d : std_logic; -- internal readable output state for write
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signal usb_wr_d : std_logic; -- internal readable output state for write
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signal addr_reg: std_logic_vector(23 downto 0);
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signal addr_reg: std_logic_vector(23 downto 0);
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--State machine
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--State machine
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signal cmd_cnt : std_logic_vector(15 downto 0);
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signal cmd_cnt : std_logic_vector(15 downto 0);
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signal state_cnt : std_logic_vector(3 downto 0);
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signal state_cnt : std_logic_vector(3 downto 0);
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--shyncro to USB
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--shyncro to USB
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signal usb_txe_nd : std_logic; -- tx fifo empty (redy for new data if low)
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signal usb_txe_nd : std_logic; -- tx fifo empty (redy for new data if low)
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signal usb_rxf_nd : std_logic; -- rx fifo empty (data redy if low)
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signal usb_rxf_nd : std_logic; -- rx fifo empty (data redy if low)
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signal internal_cmd : std_logic; -- rx fifo empty (data redy if low)
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signal internal_cmd : std_logic; -- rx fifo empty (data redy if low)
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signal read_mode : std_logic;
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signal read_mode : std_logic;
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signal write_mode : std_logic;
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signal write_mode : std_logic;
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signal write_count : std_logic;
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signal write_count : std_logic;
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signal first_word : std_logic;
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signal first_word : std_logic;
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signal mem_busy_nd : std_logic;
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signal mem_busy_nd : std_logic;
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begin
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begin
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--define internal command codes
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--define internal command codes
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internal_cmd <='1' when data_reg_i(7 downto 0) = x"C5" else
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internal_cmd <='1' when data_reg_i(7 downto 0) = x"C5" else
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'1' when data_reg_i(7 downto 0) = x"CD" else
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'1' when data_reg_i(7 downto 0) = x"CD" else
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'1' when data_reg_i(7 downto 0) = x"A0" else
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'1' when data_reg_i(7 downto 0) = x"A0" else
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'1' when data_reg_i(7 downto 0) = x"A1" else
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'1' when data_reg_i(7 downto 0) = x"A1" else
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'1' when data_reg_i(7 downto 0) = x"A2" else
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'1' when data_reg_i(7 downto 0) = x"A2" else
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'1' when data_reg_i(7 downto 0) = x"3F" else
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'1' when data_reg_i(7 downto 0) = x"3F" else
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--These are spechial attention Flash commands
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--These are spechial attention Flash commands
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'1' when data_reg_i(7 downto 0) = x"E8" else
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'1' when data_reg_i(7 downto 0) = x"E8" else
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'0';
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'0';
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usb_wr <= usb_wr_d when usb_mode_en='1' else
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usb_wr <= usb_wr_d when usb_mode_en='1' else
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'Z';
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'Z';
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-- this goes to byte buffer for that reason send LSB first and MSB second
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-- this goes to byte buffer for that reason send LSB first and MSB second
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usb_bd <=data_reg_o(7 downto 0)when data_oe='1' and CS=TXCMD0s and usb_mode_en='1' else --LSB byte first
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usb_bd <=data_reg_o(7 downto 0)when data_oe='1' and CS=TXCMD0s and usb_mode_en='1' else --LSB byte first
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data_reg_o(15 downto 8) when data_oe='1' and CS=TXCMD1s and usb_mode_en='1' else --MSB byte second
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data_reg_o(15 downto 8) when data_oe='1' and CS=TXCMD1s and usb_mode_en='1' else --MSB byte second
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(others=>'Z');
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(others=>'Z');
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process (clk25,reset_n) --enable the scanning while in reset (simulation will be incorrect)
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process (clk25,reset_n) --enable the scanning while in reset (simulation will be incorrect)
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begin -- process
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begin -- process
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if reset_n='0' then
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if reset_n='0' then
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CS <= RESETs;
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CS <= RESETs;
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usb_rd_n <= '1';
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usb_rd_n <= '1';
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usb_wr_d <= '0';
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usb_wr_d <= '0';
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usb_txe_nd <= '1';
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usb_txe_nd <= '1';
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usb_rxf_nd <= '1';
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usb_rxf_nd <= '1';
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data_oe <='0';
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data_oe <='0';
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state_cnt <=(others=>'0'); --init command counter
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state_cnt <=(others=>'0'); --init command counter
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mem_do <= (others=>'Z');
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mem_do <= (others=>'Z');
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mem_addr <= (others=>'Z');
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mem_addr <= (others=>'Z');
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addr_reg <= (others=>'0');
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addr_reg <= (others=>'0');
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mem_val <= '0';
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mem_val <= '0';
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mem_wr <='0';
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mem_wr <='0';
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mem_cmd <='0';
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mem_cmd <='0';
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cmd_cnt <= (others=>'0');
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cmd_cnt <= (others=>'0');
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read_mode <='0';
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read_mode <='0';
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write_mode <='0';
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write_mode <='0';
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write_count <='0';
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write_count <='0';
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first_word <='0';
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first_word <='0';
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mem_idle <='1'; --set idle
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mem_idle <='1'; --set idle
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mem_busy_nd <='1';
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mem_busy_nd <='1';
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elsif clk25'event and clk25 = '1' then -- rising clock edge
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elsif clk25'event and clk25 = '1' then -- rising clock edge
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usb_txe_nd <= usb_txe_n; --syncronize
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usb_txe_nd <= usb_txe_n; --syncronize
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usb_rxf_nd <= usb_rxf_n; --syncronize
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usb_rxf_nd <= usb_rxf_n; --syncronize
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mem_busy_nd <=mem_busy_n; --syncronize
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mem_busy_nd <=mem_busy_n; --syncronize
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case CS is
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case CS is
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when RESETs =>
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when RESETs =>
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if usb_rxf_nd='0' and usb_mode_en='1' and mem_busy_nd='1' then
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if usb_rxf_nd='0' and usb_mode_en='1' and mem_busy_nd='1' then
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state_cnt <=(others=>'0'); --init command counter
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state_cnt <=(others=>'0'); --init command counter
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data_oe <='0'; --we will read command in
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data_oe <='0'; --we will read command in
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mem_idle <='0'; --set busy untill return here
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mem_idle <='0'; --set busy untill return here
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CS <= RXCMD0s;
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CS <= RXCMD0s;
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elsif mem_busy_nd='1' then
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elsif mem_busy_nd='1' then
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mem_idle <='1'; --set idle when here
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mem_idle <='1'; --set idle when here
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end if;
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end if;
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when RXCMD0s =>
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when RXCMD0s =>
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if state_cnt="0000" then
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if state_cnt="0000" then
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usb_rd_n <='0'; -- set read low
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usb_rd_n <='0'; -- set read low
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state_cnt <= state_cnt + 1;-- must be min 50ns long (two cycles)
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state_cnt <= state_cnt + 1;-- must be min 50ns long (two cycles)
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elsif state_cnt="0001" then
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elsif state_cnt="0001" then
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state_cnt <= state_cnt + 1;-- one wait cycle
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state_cnt <= state_cnt + 1;-- one wait cycle
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elsif state_cnt="0010" then
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elsif state_cnt="0010" then
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state_cnt <= state_cnt + 1;-- now is ok
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state_cnt <= state_cnt + 1;-- now is ok
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data_reg_i(15 downto 8) <= usb_bd; --get data form bus MSByte must come first
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data_reg_i(15 downto 8) <= usb_bd; --get data form bus MSByte must come first
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elsif state_cnt="0011" then
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elsif state_cnt="0011" then
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usb_rd_n <='1'; -- set read back to high
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usb_rd_n <='1'; -- set read back to high
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state_cnt <= state_cnt + 1;-- start wait
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state_cnt <= state_cnt + 1;-- start wait
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elsif state_cnt="0100" then
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elsif state_cnt="0100" then
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state_cnt <= state_cnt + 1;-- wait (the usb_rxf_n toggles after each read and next data is not ready)
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state_cnt <= state_cnt + 1;-- wait (the usb_rxf_n toggles after each read and next data is not ready)
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elsif state_cnt="0101" then
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elsif state_cnt="0101" then
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state_cnt <= state_cnt + 1;-- wait
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state_cnt <= state_cnt + 1;-- wait
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elsif state_cnt="0110" then
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elsif state_cnt="0110" then
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state_cnt <= state_cnt + 1;-- now is ok prob.
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state_cnt <= state_cnt + 1;-- now is ok prob.
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else
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else
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if usb_rxf_nd='0' then --wait untill next byte is available
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if usb_rxf_nd='0' then --wait untill next byte is available
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state_cnt <=(others=>'0'); --init command counter
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state_cnt <=(others=>'0'); --init command counter
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CS <= RXCMD1s;
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CS <= RXCMD1s;
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end if;
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end if;
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end if;
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end if;
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when RXCMD1s =>
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when RXCMD1s =>
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if state_cnt="0000" then
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if state_cnt="0000" then
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usb_rd_n <='0'; -- set read low
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usb_rd_n <='0'; -- set read low
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state_cnt <= state_cnt + 1;-- must be min 50ns long (two cycles)
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state_cnt <= state_cnt + 1;-- must be min 50ns long (two cycles)
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elsif state_cnt="0001" then
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elsif state_cnt="0001" then
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state_cnt <= state_cnt + 1;-- one wait cycle
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state_cnt <= state_cnt + 1;-- one wait cycle
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elsif state_cnt="0010" then
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elsif state_cnt="0010" then
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state_cnt <= state_cnt + 1;-- now is ok
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state_cnt <= state_cnt + 1;-- now is ok
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data_reg_i(7 downto 0) <= usb_bd; --get data form bus LSByte must come last
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data_reg_i(7 downto 0) <= usb_bd; --get data form bus LSByte must come last
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elsif state_cnt="0011" then
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elsif state_cnt="0011" then
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state_cnt <= state_cnt + 1;-- now is ok
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state_cnt <= state_cnt + 1;-- now is ok
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usb_rd_n <='1'; -- set read back to high
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usb_rd_n <='1'; -- set read back to high
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elsif state_cnt="0100" then
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elsif state_cnt="0100" then
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state_cnt <= state_cnt + 1;-- wait (the usb_rxf_n toggles after each read and next data is not ready)
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state_cnt <= state_cnt + 1;-- wait (the usb_rxf_n toggles after each read and next data is not ready)
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elsif state_cnt="0101" then
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elsif state_cnt="0101" then
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state_cnt <= state_cnt + 1;-- wait
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state_cnt <= state_cnt + 1;-- wait
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elsif state_cnt="0110" then
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elsif state_cnt="0110" then
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state_cnt <= state_cnt + 1;-- now is ok prob.
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state_cnt <= state_cnt + 1;-- now is ok prob.
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else
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else
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state_cnt <=(others=>'0'); --init command counter
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state_cnt <=(others=>'0'); --init command counter
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CS <= INTERNs;
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CS <= INTERNs;
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end if;
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end if;
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when INTERNs =>
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when INTERNs =>
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if cmd_cnt=x"0000" then
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if cmd_cnt=x"0000" then
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if data_reg_i(7 downto 0)=x"A0" then
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if data_reg_i(7 downto 0)=x"A0" then
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addr_reg(7 downto 0)<= data_reg_i(15 downto 8);
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addr_reg(7 downto 0)<= data_reg_i(15 downto 8);
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CS <= RESETs; --go back to resets
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CS <= RESETs; --go back to resets
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elsif data_reg_i(7 downto 0)=x"A1" then
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elsif data_reg_i(7 downto 0)=x"A1" then
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addr_reg(15 downto 8)<= data_reg_i(15 downto 8);
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addr_reg(15 downto 8)<= data_reg_i(15 downto 8);
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CS <= RESETs; --go back to resets
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CS <= RESETs; --go back to resets
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elsif data_reg_i(7 downto 0)=x"A2" then
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elsif data_reg_i(7 downto 0)=x"A2" then
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addr_reg(23 downto 16)<= data_reg_i(15 downto 8);
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addr_reg(23 downto 16)<= data_reg_i(15 downto 8);
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CS <= RESETs; --go back to resets
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CS <= RESETs; --go back to resets
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elsif data_reg_i(7 downto 0)=x"3F" then
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elsif data_reg_i(7 downto 0)=x"3F" then
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CS <= RESETs; --go back to resets --NOP command
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CS <= RESETs; --go back to resets --NOP command
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elsif data_reg_i(7 downto 0)=x"C5" then
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elsif data_reg_i(7 downto 0)=x"C5" then
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if (data_reg_i(15 downto 8))=x"00" then
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if (data_reg_i(15 downto 8))=x"00" then
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data_reg_o <=x"3210";
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data_reg_o <=x"3210";
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else
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else
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data_reg_o <=dongle_ver;
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data_reg_o <=dongle_ver;
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end if;
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end if;
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CS <= TXCMD0s;
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CS <= TXCMD0s;
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elsif data_reg_i(7 downto 0)=x"CD" then
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elsif data_reg_i(7 downto 0)=x"CD" then
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if (data_reg_i(15 downto 8))=x"00" then --64K word read coming
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if (data_reg_i(15 downto 8))=x"00" then --64K word read coming
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cmd_cnt <= (others=>'1'); --64K word count
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cmd_cnt <= (others=>'1'); --64K word count
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else
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else
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cmd_cnt <= x"00"&data_reg_i(15 downto 8) - 1; -- -1 as one read will be done right now (cmd_cnt words)
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cmd_cnt <= x"00"&data_reg_i(15 downto 8) - 1; -- -1 as one read will be done right now (cmd_cnt words)
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end if;
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end if;
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CS <= VCIRDs; --go perform a read
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CS <= VCIRDs; --go perform a read
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read_mode <='1';
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read_mode <='1';
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elsif data_reg_i(7 downto 0)=x"E8" then
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elsif data_reg_i(7 downto 0)=x"E8" then
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--write_mode <='1';
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--write_mode <='1';
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write_count <='0';
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write_count <='0';
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first_word <='0';
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first_word <='0';
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cmd_cnt <= x"00"&data_reg_i(15 downto 8) + 1; --+2 for direct count write +1
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cmd_cnt <= x"00"&data_reg_i(15 downto 8) + 1; --+2 for direct count write +1
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data_reg_i(15 downto 8)<=(others=>'0');
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data_reg_i(15 downto 8)<=(others=>'0');
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CS <= VCIWRs; --go perform a write
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CS <= VCIWRs; --go perform a write
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else
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else
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CS <= VCIWRs;
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CS <= VCIWRs;
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end if;
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end if;
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else
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else
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if cmd_cnt>x"0000" then
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if cmd_cnt>x"0000" then
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cmd_cnt<= cmd_cnt - 1;
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cmd_cnt<= cmd_cnt - 1;
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if write_count='0' then
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if write_count='0' then
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write_count<='1';
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write_count<='1';
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elsif write_count='1' and first_word ='0' then
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elsif write_count='1' and first_word ='0' then
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first_word <='1';
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first_word <='1';
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elsif write_count='1' and first_word ='1' then
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elsif write_count='1' and first_word ='1' then
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addr_reg <= addr_reg + 1; --autoincrement address in in block mode
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addr_reg <= addr_reg + 1; --autoincrement address in in block mode
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end if;
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end if;
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--if cmd_cnt>x"02" then --so not to increase too many times on write buffer
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--if cmd_cnt>x"02" then --so not to increase too many times on write buffer
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-- addr_reg <= addr_reg + 1; --autoincrement address in in block mode
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-- addr_reg <= addr_reg + 1; --autoincrement address in in block mode
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--end if;
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--end if;
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end if;
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end if;
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CS <= VCIWRs;
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CS <= VCIWRs;
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end if;
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end if;
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when VCIRDs => --flash read
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when VCIRDs => --flash read
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mem_wr <='0'; --this is VCI write_not_read
|
mem_wr <='0'; --this is VCI write_not_read
|
mem_cmd <='0';
|
mem_cmd <='0';
|
mem_addr <= addr_reg(22 downto 0)&'0'; --translate byte address to word address
|
mem_addr <= addr_reg(22 downto 0)&'0'; --translate byte address to word address
|
mem_val <= '1';
|
mem_val <= '1';
|
if mem_ack='1' then
|
if mem_ack='1' then
|
data_reg_o <= mem_di;
|
data_reg_o <= mem_di;
|
mem_wr <='0'; --this is VCI write_not_read
|
mem_wr <='0'; --this is VCI write_not_read
|
mem_cmd <='0';
|
mem_cmd <='0';
|
mem_val <= '0';
|
mem_val <= '0';
|
CS <= TXCMD0s;
|
CS <= TXCMD0s;
|
end if;
|
end if;
|
when VCIWRs => --flash write
|
when VCIWRs => --flash write
|
mem_addr <= addr_reg(22 downto 0)&'0'; --translate byte address to word address
|
mem_addr <= addr_reg(22 downto 0)&'0'; --translate byte address to word address
|
mem_do <= data_reg_i; --USB data in will go to mem_out
|
mem_do <= data_reg_i; --USB data in will go to mem_out
|
mem_wr <='1'; --this is VCI write_not_read
|
mem_wr <='1'; --this is VCI write_not_read
|
mem_cmd <='1';
|
mem_cmd <='1';
|
mem_val <= '1';
|
mem_val <= '1';
|
if mem_ack='1' then
|
if mem_ack='1' then
|
mem_do <= (others=>'Z');
|
mem_do <= (others=>'Z');
|
mem_wr <='0'; --this is VCI write_not_read
|
mem_wr <='0'; --this is VCI write_not_read
|
mem_cmd <='0';
|
mem_cmd <='0';
|
mem_val <= '0';
|
mem_val <= '0';
|
--if write_mode='0' then
|
--if write_mode='0' then
|
|
|
if cmd_cnt=x"0000" then --if flash command and not data
|
if cmd_cnt=x"0000" then --if flash command and not data
|
state_cnt <=(others=>'0'); --init command counter
|
state_cnt <=(others=>'0'); --init command counter
|
CS <= STS_WAITs;
|
CS <= STS_WAITs;
|
else
|
else
|
CS <= RESETs;
|
CS <= RESETs;
|
end if;
|
end if;
|
--else --else if was 0xE8 must read and return XSR
|
--else --else if was 0xE8 must read and return XSR
|
-- write_mode <='0'; --XSR return will no follow clear this bit
|
-- write_mode <='0'; --XSR return will no follow clear this bit
|
-- CS <= VCIRDs;
|
-- CS <= VCIRDs;
|
--end if;
|
--end if;
|
end if;
|
end if;
|
when TXCMD0s => --transmit over USB what ever is in data_reg_o MSB first
|
when TXCMD0s => --transmit over USB what ever is in data_reg_o MSB first
|
|
|
if state_cnt="0000" then
|
if state_cnt="0000" then
|
if usb_txe_nd='0' then
|
if usb_txe_nd='0' then
|
usb_wr_d<='1'; -- data is mux'ed by state and data_oe in the beginning of arch
|
usb_wr_d<='1'; -- data is mux'ed by state and data_oe in the beginning of arch
|
state_cnt <= state_cnt + 1;-- now is ok
|
state_cnt <= state_cnt + 1;-- now is ok
|
end if;
|
end if;
|
elsif state_cnt="0010" then
|
elsif state_cnt="0010" then
|
data_oe<='1'; --this is to put data on bus befora falling edge of wr (max 20ns before)
|
data_oe<='1'; --this is to put data on bus befora falling edge of wr (max 20ns before)
|
state_cnt <= state_cnt + 1;-- now is ok
|
state_cnt <= state_cnt + 1;-- now is ok
|
elsif state_cnt="0011" then
|
elsif state_cnt="0011" then
|
usb_wr_d<='0'; --falling edge performs write must be high for atleast 50ns
|
usb_wr_d<='0'; --falling edge performs write must be high for atleast 50ns
|
state_cnt <= state_cnt + 1;-- now is ok
|
state_cnt <= state_cnt + 1;-- now is ok
|
elsif state_cnt="0100" then
|
elsif state_cnt="0100" then
|
state_cnt <= state_cnt + 1;-- now is ok
|
state_cnt <= state_cnt + 1;-- now is ok
|
data_oe<='0';
|
data_oe<='0';
|
elsif state_cnt="0111" then --must stay low at least 50ns
|
elsif state_cnt="0111" then --must stay low at least 50ns
|
CS <= TXCMD1s;
|
CS <= TXCMD1s;
|
state_cnt <= (others=>'0');
|
state_cnt <= (others=>'0');
|
else
|
else
|
state_cnt <= state_cnt + 1;-- if intermediate cnt then count
|
state_cnt <= state_cnt + 1;-- if intermediate cnt then count
|
end if;
|
end if;
|
|
|
when TXCMD1s =>
|
when TXCMD1s =>
|
|
|
if state_cnt="0000" then
|
if state_cnt="0000" then
|
if usb_txe_nd='0' then
|
if usb_txe_nd='0' then
|
usb_wr_d<='1'; -- data is mux'ed by state and data_oe in the beginning of arch
|
usb_wr_d<='1'; -- data is mux'ed by state and data_oe in the beginning of arch
|
state_cnt <= state_cnt + 1;-- now is ok
|
state_cnt <= state_cnt + 1;-- now is ok
|
end if;
|
end if;
|
elsif state_cnt="0010" then
|
elsif state_cnt="0010" then
|
data_oe<='1'; --this is to put data on bus befora falling edge of wr (max 20ns before)
|
data_oe<='1'; --this is to put data on bus befora falling edge of wr (max 20ns before)
|
state_cnt <= state_cnt + 1;-- now is ok
|
state_cnt <= state_cnt + 1;-- now is ok
|
elsif state_cnt="0011" then
|
elsif state_cnt="0011" then
|
usb_wr_d<='0'; --falling edge performs write must be high for atleast 50ns
|
usb_wr_d<='0'; --falling edge performs write must be high for atleast 50ns
|
state_cnt <= state_cnt + 1;-- now is ok
|
state_cnt <= state_cnt + 1;-- now is ok
|
elsif state_cnt="0100" then
|
elsif state_cnt="0100" then
|
state_cnt <= state_cnt + 1;-- now is ok
|
state_cnt <= state_cnt + 1;-- now is ok
|
data_oe<='0';
|
data_oe<='0';
|
elsif state_cnt="0111" then --must stay low at least 50ns
|
elsif state_cnt="0111" then --must stay low at least 50ns
|
if read_mode='0' then
|
if read_mode='0' then
|
CS <= RESETs;
|
CS <= RESETs;
|
elsif cmd_cnt="0000" then --last word sent
|
elsif cmd_cnt="0000" then --last word sent
|
addr_reg <= addr_reg + 1; --autoincrement address in read mode
|
addr_reg <= addr_reg + 1; --autoincrement address in read mode
|
read_mode <='0';
|
read_mode <='0';
|
CS <= RESETs;
|
CS <= RESETs;
|
else
|
else
|
cmd_cnt<= cmd_cnt - 1;
|
cmd_cnt<= cmd_cnt - 1;
|
addr_reg <= addr_reg + 1; --autoincrement address in read mode
|
addr_reg <= addr_reg + 1; --autoincrement address in read mode
|
CS <= VCIRDs; --more data to be read
|
CS <= VCIRDs; --more data to be read
|
end if;
|
end if;
|
state_cnt <= (others=>'0');
|
state_cnt <= (others=>'0');
|
else
|
else
|
state_cnt <= state_cnt + 1;-- if intermediate cnt then count
|
state_cnt <= state_cnt + 1;-- if intermediate cnt then count
|
end if;
|
end if;
|
when STS_WAITs =>
|
when STS_WAITs =>
|
if mem_busy_nd='0' then
|
if mem_busy_nd='0' then
|
CS <= RESETs; --now it's ok to go here
|
CS <= RESETs; --now it's ok to go here
|
else
|
else
|
state_cnt <= state_cnt + 1;
|
state_cnt <= state_cnt + 1;
|
if state_cnt="1111" then
|
if state_cnt="1111" then
|
--sts cant take longer than 500 ns to go low
|
--sts cant take longer than 500 ns to go low
|
CS <= RESETs; --time out go to resets anyway
|
CS <= RESETs; --time out go to resets anyway
|
end if;
|
end if;
|
end if;
|
end if;
|
when others => null;
|
when others => null;
|
end case;
|
end case;
|
end if;
|
end if;
|
end process;
|
end process;
|
|
|
|
|
|
|
end RTL;
|
end RTL;
|
|
|
|
|
