| Line 61... |
Line 61... |
-- Architecture declaration
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-- Architecture declaration
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-------------------------------------------------------------------------------------
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-------------------------------------------------------------------------------------
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architecture rtl of ow_search is
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architecture rtl of ow_search is
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type h_state_type is (H_IDLE, H_RST, H_SKIP, H_READBIT, H_READCMP, H_PARSE, H_INCLOOP, H_FILL, H_ERROR);
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type h_state_type is (H_IDLE, H_RST, H_WRCMD, H_READBIT, H_READCMP, H_PARSE, H_INCLOOP, H_FILL, H_ERROR);
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signal h_state : h_state_type := H_IDLE;
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signal h_state : h_state_type := H_IDLE;
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type f_state_type is (F_IDLE, F_FIND, F_INC);
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type f_state_type is (F_IDLE, F_FIND, F_INC);
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signal f_state : f_state_type := F_IDLE;
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signal f_state : f_state_type := F_IDLE;
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signal idcnt : integer range 0 to 31;
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signal idcnt : integer range 0 to 31;
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signal lastfork : integer range 0 to 63;
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signal lastfork : integer range 0 to 64;
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signal lastzero : integer range 0 to 63;
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signal zerofork : integer range 0 to 64;
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signal idbitnum : integer range 0 to 63;
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signal idbitnum : integer range 0 to 63;
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signal lastdev : std_logic := '0';
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signal lastdev : std_logic := '0';
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signal h_err : std_logic := '0';
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signal h_err : std_logic := '0';
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signal f_err : std_logic := '0';
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signal f_err : std_logic := '0';
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signal irdbit : std_logic := '0';
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signal irdbit : std_logic := '0';
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| Line 92... |
Line 92... |
attribute mark_debug : string;
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attribute mark_debug : string;
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attribute mark_debug of f_state : signal is "true";
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attribute mark_debug of f_state : signal is "true";
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attribute mark_debug of h_state : signal is "true";
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attribute mark_debug of h_state : signal is "true";
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attribute mark_debug of idbitnum : signal is "true";
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attribute mark_debug of idbitnum : signal is "true";
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attribute mark_debug of lastfork : signal is "true";
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attribute mark_debug of lastfork : signal is "true";
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attribute mark_debug of lastzero : signal is "true";
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attribute mark_debug of zerofork : signal is "true";
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attribute mark_debug of rxpat : signal is "true";
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attribute mark_debug of rxpat : signal is "true";
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attribute mark_debug of iwrbyte : signal is "true";
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attribute mark_debug of iwrbyte : signal is "true";
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attribute mark_debug of irdbit : signal is "true";
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attribute mark_debug of irdbit : signal is "true";
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attribute mark_debug of iwrbit : signal is "true";
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attribute mark_debug of iwrbit : signal is "true";
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attribute mark_debug of iwe : signal is "true";
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attribute mark_debug of iwe : signal is "true";
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| Line 112... |
Line 112... |
------------------------------------------------------
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------------------------------------------------------
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-- HUNT - search for the next device on bus ---
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-- HUNT - search for the next device on bus ---
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------------------------------------------------------
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------------------------------------------------------
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--p_hunt - hunts for the next device using the algorithm described in Maxim (Analog Devices) app note APP187
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--p_hunt - hunts for the next device using the algorithm described in Maxim (Analog Devices) app note APP187
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-- the app note is modified slightly for optimization in VHDL
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-- the app note is modified slightly for optimization in VHDL
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-- "restart" resets all parameters to rediscover all ROM iDs
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-- the algorithm works by taking successive passes through the address field with each pass revealing the next device
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-- "hunt" searches for the next ROM ID in the sort order
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-- address in alphabetic order. The first pass takes the 0 path at each conflicting address bit (or fork). By keeping
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-- track of the last conflicting bit in variable zerofork/lastfork, the algorithm knows were to deviate from the
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-- present address on the next pass. On subsequent passes, for all conflicts up to the lastfork,
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-- the same fork is taken as was taken on the previous pass, which could be a 1 or 0. At the fork at the lastfork,
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-- the 1 path is taken, because the 0 path was taken in the previous pass. The variable zerofork is used to keep track
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-- of the last fork for this pass at which a zero path was taken, and lastfork is the zerofork from the previous pass.
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-- zerofork and lastfork are set to 64 if there are no zero forks taken.
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-- If no zero forks were taken, then the last device was found and the lastdev is set, afterwhich the FILL state
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-- is used to zero out the remaining unused ID memeory locations
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--
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p_hunt : process (clk)
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p_hunt : process (clk)
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begin
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begin
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if rising_edge(clk) then
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if rising_edge(clk) then
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if srst = '1' or restart = '1' then
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if srst = '1' or restart = '1' then
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--Start a new search, put all signals into default state, and start in H_IDLE state
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h_state <= H_IDLE;
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h_state <= H_IDLE;
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idbitnum <= 0;
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idbitnum <= 0;
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lastfork <= 0;
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lastfork <= 64;
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zerofork <= 64;
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lastdev <= '0';
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lastdev <= '0';
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rxpat <= "00";
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rxpat <= "00";
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h_err <= '0';
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h_err <= '0';
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iwrbyte <= '0';
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iwrbyte <= '0';
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izzbit <= '0';
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izzbit <= '0';
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| Line 134... |
Line 145... |
iobit <= '0';
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iobit <= '0';
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obyte <= x"00";
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obyte <= x"00";
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else
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else
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case h_state is
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case h_state is
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when H_IDLE =>
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when H_IDLE =>
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--when in idle, all signals in default state
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idbitnum <= 0;
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idbitnum <= 0;
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lastzero <= 0;
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zerofork <= 64;
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rxpat <= "00";
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rxpat <= "00";
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iwrbyte <= '0';
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iwrbyte <= '0';
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irdbit <= '0';
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irdbit <= '0';
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iwrbit <= '0';
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iwrbit <= '0';
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iwe <= '0';
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iwe <= '0';
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iobit <= '0';
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iobit <= '0';
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obyte <= x"00";
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obyte <= x"00";
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if h_start = '1' then
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if h_start = '1' then
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--detected command to search for next onewire device
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if lastdev = '0' then
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if lastdev = '0' then
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--first time thorough, reset the one-wire bus
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h_state <= H_RST;
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h_state <= H_RST;
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izzbit <= '1';
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izzbit <= '1'; --send reset signal
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h_err <= '0';
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h_err <= '0';
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else
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else
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h_state <= H_FILL;
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h_state <= H_FILL;
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iwe <= '1';
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iwe <= '1';
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iobit <= '0';
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iobit <= '0';
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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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izzbit <= '0';
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izzbit <= '0';
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end if;
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end if;
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when H_RST =>
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when H_RST =>
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--reset the bus at start of each pass, all devices are activated
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if izzbit = '1' then
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if izzbit = '1' then
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izzbit <= '0';
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izzbit <= '0'; --terminate the reset request
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elsif busyin = '0' then
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elsif busyin = '0' then
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--reset is completed, the devices should have responded
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if ibit = '1' then
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if ibit = '1' then
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--no response, no devices on bus, so error out
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h_state <= H_ERROR;
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h_state <= H_ERROR;
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else
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else
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--send "search rom" command
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obyte <= x"f0";
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obyte <= x"f0";
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iwrbyte <= '1';
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iwrbyte <= '1';
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h_state <= H_SKIP;
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h_state <= H_WRCMD;
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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 H_SKIP =>
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when H_WRCMD =>
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--waits for end write command byte, then reads a response bit
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if iwrbyte = '1' then
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if iwrbyte = '1' then
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iwrbyte <= '0';
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iwrbyte <= '0'; --terminate write "search rom" command request
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elsif busyin = '0' then
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elsif busyin = '0' then
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-- when the write command is completed
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-- read a bit, this will be the AND of the
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-- first address bit of all devices on the bus
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irdbit <= '1';
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irdbit <= '1';
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h_state <= H_READBIT;
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h_state <= H_READBIT;
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end if;
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end if;
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when H_READBIT =>
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when H_READBIT =>
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--reads the address bit
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if irdbit = '1' then
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if irdbit = '1' then
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irdbit <= '0';
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irdbit <= '0'; --terminate the read bit request
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elsif busyin = '0' then
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elsif busyin = '0' then
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--wait until bit is read
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--save the AND of the address bit of all devices
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rxpat(1) <= ibit;
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rxpat(1) <= ibit;
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--and read the AND of the compliment of the address bit of all devices
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irdbit <= '1';
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irdbit <= '1';
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h_state <= H_READCMP;
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h_state <= H_READCMP;
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end if;
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end if;
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when H_READCMP =>
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when H_READCMP =>
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--reads the complement of the address bit
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if irdbit = '1' then
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if irdbit = '1' then
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irdbit <= '0';
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irdbit <= '0'; --terminate the read complement bit request
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elsif busyin = '0' then
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elsif busyin = '0' then
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--when bit is read,
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--save the AND of the complimented address bit of all devices
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rxpat(0) <= ibit;
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rxpat(0) <= ibit;
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h_state <= H_PARSE;
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h_state <= H_PARSE;
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end if;
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end if;
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when H_PARSE =>
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when H_PARSE =>
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--with the AND of the address bit and the AND of the complimented address bit
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-- decide how to proceed (see APP note)
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case rxpat is
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case rxpat is
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when "11" =>
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when "11" =>
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--no device responded
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h_state <= H_ERROR;
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h_state <= H_ERROR;
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when "00" =>
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when "00" =>
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--00 indicates a conflict, devices disagree on this bit
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if idbitnum = lastfork then
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if idbitnum = lastfork then
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--last_romid(63 downto 0) <= last_romid(0) & last_romid(63 downto 1);
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--last_romid(63 downto 0) <= last_romid(0) & last_romid(63 downto 1);
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--new_romid(63 downto 0) <= '1' & new_romid(63 downto 1);
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--new_romid(63 downto 0) <= '1' & new_romid(63 downto 1);
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iobit <= '1';
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iobit <= '1';
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iwrbit <= '1';
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iwrbit <= '1';
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| Line 208... |
Line 241... |
--last_romid(63 downto 0) <= last_romid(0) & last_romid(63 downto 1);
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--last_romid(63 downto 0) <= last_romid(0) & last_romid(63 downto 1);
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--new_romid(63 downto 0) <= '0' & new_romid(63 downto 1);
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--new_romid(63 downto 0) <= '0' & new_romid(63 downto 1);
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iobit <= '0';
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iobit <= '0';
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iwrbit <= '1';
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iwrbit <= '1';
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iwe <= '1';
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iwe <= '1';
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lastzero <= idbitnum;
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zerofork <= idbitnum;
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h_state <= H_INCLOOP;
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h_state <= H_INCLOOP;
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else
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else
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--last_romid(63 downto 0) <= last_romid(0) & last_romid(63 downto 1);
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--last_romid(63 downto 0) <= last_romid(0) & last_romid(63 downto 1);
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--new_romid(63 downto 0) <= last_romid(0) & new_romid(63 downto 1);
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--new_romid(63 downto 0) <= last_romid(0) & new_romid(63 downto 1);
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iobit <= id_rbit;
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iobit <= id_rbit;
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iwrbit <= '1';
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iwrbit <= '1';
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iwe <= '1';
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iwe <= '1';
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if id_rbit = '0' then
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if id_rbit = '0' then
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lastzero <= idbitnum;
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zerofork <= idbitnum;
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end if;
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end if;
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h_state <= H_INCLOOP;
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h_state <= H_INCLOOP;
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end if;
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end if;
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when others =>
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when others =>
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--last_romid(63 downto 0) <= last_romid(0) & last_romid(63 downto 1);
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--last_romid(63 downto 0) <= last_romid(0) & last_romid(63 downto 1);
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| Line 230... |
Line 263... |
iwrbit <= '1';
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iwrbit <= '1';
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iwe <= '1';
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iwe <= '1';
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h_state <= H_INCLOOP;
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h_state <= H_INCLOOP;
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end case;
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end case;
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when H_INCLOOP =>
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when H_INCLOOP =>
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--increments the search to the next bit and terminates when all bits are finished
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if iwrbit = '1' or iwe = '1' then
|
if iwrbit = '1' or iwe = '1' then
|
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--terminate the write request of the current bit
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iwrbit <= '0';
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iwrbit <= '0';
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iwe <= '0';
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iwe <= '0';
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elsif busyin = '0' then
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elsif busyin = '0' then
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if idbitnum = 63 then
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if idbitnum = 63 then
|
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--at end of the address, go back to idle, and move lastzero to lastfork
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h_state <= H_IDLE;
|
h_state <= H_IDLE;
|
lastfork <= lastzero;
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lastfork <= zerofork;
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if lastzero = 0 then
|
if zerofork = 64 then
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lastdev <= '1';
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lastdev <= '1'; --make last device if there no zero forks were taken
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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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-- continue on with next bit by requesting a read of the next address bit
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idbitnum <= idbitnum + 1;
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idbitnum <= idbitnum + 1;
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irdbit <= '1';
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irdbit <= '1';
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h_state <= H_READBIT;
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h_state <= H_READBIT;
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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 H_FILL =>
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when H_FILL =>
|
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--this fills the unused address feilds with zeros after the last device is found.
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if iwe = '1' then
|
if iwe = '1' then
|
iwe <= '0';
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iwe <= '0';
|
elsif idbitnum = 63 then
|
elsif idbitnum = 63 then
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h_state <= H_IDLE;
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h_state <= H_IDLE;
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else
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else
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| Line 278... |
Line 316... |
begin
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begin
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if rising_edge(clk) then
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if rising_edge(clk) then
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if srst = '1' then
|
if srst = '1' then
|
idcnt <= 0;
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idcnt <= 0;
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f_state <= F_IDLE;
|
f_state <= F_IDLE;
|
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h_start <= '0';
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restart <= '0';
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restart <= '0';
|
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f_err <= '0';
|
else
|
else
|
case f_state is
|
case f_state is
|
when F_IDLE =>
|
when F_IDLE =>
|
if start = '1' then
|
if start = '1' then
|
restart <= '1';
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restart <= '1';
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| Line 292... |
Line 332... |
f_state <= F_FIND;
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f_state <= F_FIND;
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idcnt <= 0;
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idcnt <= 0;
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f_err <= '0';
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f_err <= '0';
|
end if;
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end if;
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when F_FIND =>
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when F_FIND =>
|
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--terminate the h_start and wait for hunt state to finish
|
if h_start = '1' then
|
if h_start = '1' then
|
h_start <= '0';
|
h_start <= '0';
|
elsif h_busy = '0' then
|
elsif h_busy = '0' then
|
|
--hunt is finished, go to inc state if no error
|
|
--error also indicates there are no more one-wire devices
|
if h_err = '1' then
|
if h_err = '1' then
|
f_state <= F_IDLE;
|
f_state <= F_IDLE;
|
f_err <= '1';
|
f_err <= '1';
|
else
|
else
|
f_state <= F_INC;
|
f_state <= F_INC;
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