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/trunk/tst_ds1621.vhd
0,0 → 1,283
-- |
-- |
-- State machine for reading data from Dallas 1621 |
-- |
-- Testsystem for i2c controller |
-- |
-- |
library ieee; |
use ieee.std_logic_1164.all; |
use ieee.std_logic_arith.all; |
|
use work.i2c.all; |
|
entity DS1621_interface is |
port ( |
clk : in std_logic; |
nReset : in std_logic; |
|
Dout : out std_logic_vector(7 downto 0); -- data read from ds1621 |
|
error : out std_logic; -- no correct ack received |
|
SCL : inout std_logic; |
SDA : inout std_logic |
); |
end entity DS1621_interface; |
|
architecture structural of DS1621_interface is |
constant SLAVE_ADDR : std_logic_vector(6 downto 0) := "1001000"; |
constant CLK_CNT : unsigned(7 downto 0) := conv_unsigned(20, 8); |
|
signal cmd_ack : std_logic; |
signal D : std_logic_vector(7 downto 0); |
signal lack, store_dout : std_logic; |
|
signal start, read, write, ack, stop : std_logic; |
signal i2c_dout : std_logic_vector(7 downto 0); |
|
begin |
-- hookup I2C controller |
u1: simple_i2c port map (clk => clk, ena => '1', clk_cnt => clk_cnt, nReset => nReset, |
read => read, write => write, start => start, stop => stop, ack_in => ack, cmd_ack => cmd_ack, |
Din => D, Dout => i2c_dout, ack_out => lack, SCL => SCL, SDA => SDA); |
|
init_statemachine : block |
type states is (i1, i2, i3, i4, i5, t1, t2, t3, t4, t5); |
signal state : states; |
begin |
nxt_state_decoder: process(clk, nReset, state) |
variable nxt_state : states; |
variable iD : std_logic_vector(7 downto 0); |
variable ierr : std_logic; |
variable istart, iread, iwrite, iack, istop : std_logic; |
variable istore_dout : std_logic; |
begin |
nxt_state := state; |
ierr := '0'; |
istore_dout := '0'; |
|
istart := start; |
iread := read; |
iwrite := write; |
iack := ack; |
istop := stop; |
iD := D; |
|
case (state) is |
-- init DS1621 |
-- 1) send start condition |
-- 2) send slave address + write |
-- 3) check ack |
-- 4) send "access config" command (0xAC) |
-- 5) check ack |
-- 6) send config register data (0x00) |
-- 7) check ack |
-- 8) send stop condition |
-- 9) send start condition |
-- 10) send slave address + write |
-- 11) check ack |
-- 12) send "start conversion" command (0xEE) |
-- 13) check ack |
-- 14) send stop condition |
|
when i1 => -- send start condition, sent slave address + write |
nxt_state := i2; |
istart := '1'; |
iread := '0'; |
iwrite := '1'; |
iack := '0'; |
istop := '0'; |
iD := (slave_addr & '0'); -- write to slave (R/W = '0') |
|
when i2 => -- send "access config" command |
if (cmd_ack = '1') then |
nxt_state := i3; |
-- check aknowledge bit |
if (lack = '1') then |
ierr := '1'; -- no acknowledge received from last command, expected ACK |
end if; |
|
istart := '0'; |
iread := '0'; |
iwrite := '1'; |
iack := '0'; |
istop := '0'; |
iD := x"AC"; |
end if; |
|
when i3 => -- send config register data, sent stop condition |
if (cmd_ack = '1') then |
nxt_state := i4; |
-- check aknowledge bit |
if (lack = '1') then |
ierr := '1'; -- no acknowledge received from last command, expected ACK |
end if; |
|
istart := '0'; |
iread := '0'; |
iwrite := '1'; |
iack := '0'; |
istop := '1'; |
iD := x"00"; |
end if; |
|
when i4 => -- send start condition, sent slave address + write |
if (cmd_ack = '1') then |
nxt_state := i5; |
|
istart := '1'; |
iread := '0'; |
iwrite := '1'; |
iack := '0'; |
istop := '0'; |
iD := (slave_addr & '0'); -- write to slave (R/W = '0') |
end if; |
|
when i5 => -- send "start conversion" command + stop condition |
if (cmd_ack = '1') then |
nxt_state := t1; |
-- check aknowledge bit |
if (lack = '1') then |
ierr := '1'; -- no acknowledge received from last command, expected ACK |
end if; |
|
istart := '0'; |
iread := '0'; |
iwrite := '1'; |
iack := '0'; |
istop := '1'; |
iD := x"EE"; |
end if; |
-- read temperature |
-- 1) sent start condition |
-- 2) sent slave address + write |
-- 3) check ack |
-- 4) sent "read temperature" command (0xAA) |
-- 5) check ack |
-- 6) sent start condition |
-- 7) sent slave address + read |
-- 8) check ack |
-- 9) read msb |
-- 10) send ack |
-- 11) read lsb |
-- 12) send nack |
-- 13) send stop condition |
|
when t1 => -- send start condition, sent slave address + write |
if (cmd_ack = '1') then |
nxt_state := t2; |
-- check aknowledge bit |
if (lack = '1') then |
ierr := '1'; -- no acknowledge received from last command, expected ACK |
end if; |
|
istart := '1'; |
iread := '0'; |
iwrite := '1'; |
iack := '0'; |
istop := '0'; |
iD := (slave_addr & '0'); -- write to slave (R/W = '0') |
end if; |
|
when t2 => -- send read temperature command |
if (cmd_ack = '1') then |
nxt_state := t3; |
-- check aknowledge bit |
if (lack = '1') then |
ierr := '1'; -- no acknowledge received from last command, expected ACK |
end if; |
|
istart := '0'; |
iread := '0'; |
iwrite := '1'; |
iack := '0'; |
istop := '0'; |
iD := x"AA"; |
end if; |
|
when t3 => -- send (repeated) start condition, send slave address + read |
if (cmd_ack = '1') then |
nxt_state := t4; |
-- check aknowledge bit |
if (lack = '1') then |
ierr := '1'; -- no acknowledge received, expected ACK |
end if; |
|
istart := '1'; |
iread := '0'; |
iwrite := '1'; |
iack := '0'; |
istop := '0'; |
iD := (slave_addr & '1'); -- read from slave (R/W = '1') |
end if; |
|
when t4 => -- read MSB (hi-byte), send acknowledge |
if (cmd_ack = '1') then |
nxt_state := t5; |
-- check aknowledge bit |
if (lack = '1') then |
ierr := '1'; -- no acknowledge received from last command, expected ACK |
end if; |
|
istart := '0'; |
iread := '1'; |
iwrite := '0'; |
iack := '0'; --ACK |
istop := '0'; |
end if; |
|
when t5 => -- read LSB (lo-byte), send acknowledge, sent stop |
if (cmd_ack = '1') then |
nxt_state := t1; |
|
istart := '0'; |
iread := '1'; |
iwrite := '0'; |
iack := '1'; --NACK |
istop := '1'; |
|
istore_dout := '1'; |
end if; |
end case; |
|
-- genregs |
if (nReset = '0') then |
state <= i1; |
error <= '0'; |
store_dout <= '0'; |
|
start <= '0'; |
read <= '0'; |
write <= '0'; |
ack <= '0'; |
stop <= '0'; |
D <= (others => '0'); |
elsif (clk'event and clk = '1') then |
state <= nxt_state; |
error <= ierr; |
store_dout <= istore_dout; |
|
start <= istart; |
read <= iread; |
write <= iwrite; |
ack <= iack; |
stop <= istop; |
D <= iD; |
end if; |
end process nxt_state_decoder; |
end block init_statemachine; |
|
-- store temp |
gen_dout : process(clk) |
begin |
if (clk'event and clk = '1') then |
if (store_dout = '1') then |
Dout <= i2c_dout; |
end if; |
end if; |
end process gen_dout; |
|
end architecture structural; |
|
|
/trunk/I2C.VHD
0,0 → 1,620
-- |
-- Simple I2C controller |
-- |
-- 1) No multimaster |
-- 2) No slave mode |
-- 3) No fifo's |
-- |
-- notes: |
-- Every command is acknowledged. Do not set a new command before previous is acknowledged. |
-- Dout is available 1 clock cycle later as cmd_ack |
-- |
|
library ieee; |
use ieee.std_logic_1164.all; |
use ieee.std_logic_arith.all; |
|
package I2C is |
component simple_i2c is |
port ( |
clk : in std_logic; |
ena : in std_logic; |
nReset : in std_logic; |
|
clk_cnt : in unsigned(7 downto 0); -- 4x SCL |
|
-- input signals |
start, |
stop, |
read, |
write, |
ack_in : std_logic; |
Din : in std_logic_vector(7 downto 0); |
|
-- output signals |
cmd_ack : out std_logic; |
ack_out : out std_logic; |
Dout : out std_logic_vector(7 downto 0); |
|
-- i2c signals |
SCL : inout std_logic; |
SDA : inout std_logic |
); |
end component simple_i2c; |
end package I2C; |
|
|
library ieee; |
use ieee.std_logic_1164.all; |
use ieee.std_logic_arith.all; |
|
entity simple_i2c is |
port ( |
clk : in std_logic; |
ena : in std_logic; |
nReset : in std_logic; |
|
clk_cnt : in unsigned(7 downto 0); -- 4x SCL |
|
-- input signals |
start, |
stop, |
read, |
write, |
ack_in : std_logic; |
Din : in std_logic_vector(7 downto 0); |
|
-- output signals |
cmd_ack : out std_logic; |
ack_out : out std_logic; |
Dout : out std_logic_vector(7 downto 0); |
|
-- i2c signals |
SCL : inout std_logic; |
SDA : inout std_logic |
); |
end entity simple_i2c; |
|
architecture structural of simple_i2c is |
component i2c_core is |
port ( |
clk : in std_logic; |
nReset : in std_logic; |
|
clk_cnt : in unsigned(7 downto 0); |
|
cmd : in std_logic_vector(2 downto 0); |
cmd_ack : out std_logic; |
busy : out std_logic; |
|
Din : in std_logic; |
Dout : out std_logic; |
|
SCL : inout std_logic; |
SDA : inout std_logic |
); |
end component i2c_core; |
|
-- commands for i2c_core |
constant CMD_NOP : std_logic_vector(2 downto 0) := "000"; |
constant CMD_START : std_logic_vector(2 downto 0) := "010"; |
constant CMD_STOP : std_logic_vector(2 downto 0) := "011"; |
constant CMD_READ : std_logic_vector(2 downto 0) := "100"; |
constant CMD_WRITE : std_logic_vector(2 downto 0) := "101"; |
|
-- signals for i2c_core |
signal core_cmd : std_logic_vector(2 downto 0); |
signal core_ack, core_busy, core_txd, core_rxd : std_logic; |
|
-- signals for shift register |
signal sr : std_logic_vector(7 downto 0); -- 8bit shift register |
signal shift, ld : std_logic; |
|
-- signals for state machine |
signal go, host_ack : std_logic; |
begin |
-- hookup i2c core |
u1: i2c_core port map (clk, nReset, clk_cnt, core_cmd, core_ack, core_busy, core_txd, core_rxd, SCL, SDA); |
|
-- generate host-command-acknowledge |
cmd_ack <= host_ack; |
|
-- generate go-signal |
go <= (read or write) and not host_ack; |
|
-- assign Dout output to shift-register |
Dout <= sr; |
|
-- assign ack_out output to core_rxd (contains last received bit) |
ack_out <= core_rxd; |
|
-- generate shift register |
shift_register: process(clk) |
begin |
if (clk'event and clk = '1') then |
if (ld = '1') then |
sr <= din; |
elsif (shift = '1') then |
sr <= (sr(6 downto 0) & core_rxd); |
end if; |
end if; |
end process shift_register; |
|
-- |
-- state machine |
-- |
statemachine : block |
type states is (st_idle, st_start, st_read, st_write, st_ack, st_stop); |
signal state : states; |
signal dcnt : unsigned(2 downto 0); |
begin |
-- |
-- command interpreter, translate complex commands into simpler I2C commands |
-- |
nxt_state_decoder: process(clk, nReset, state) |
variable nxt_state : states; |
variable idcnt : unsigned(2 downto 0); |
variable ihost_ack : std_logic; |
variable icore_cmd : std_logic_vector(2 downto 0); |
variable icore_txd : std_logic; |
variable ishift, iload : std_logic; |
begin |
-- 8 databits (1byte) of data to shift-in/out |
idcnt := dcnt; |
|
-- no acknowledge (until command complete) |
ihost_ack := '0'; |
|
icore_txd := core_txd; |
|
-- keep current command to i2c_core |
icore_cmd := core_cmd; |
|
-- no shifting or loading of shift-register |
ishift := '0'; |
iload := '0'; |
|
-- keep current state; |
nxt_state := state; |
case state is |
when st_idle => |
if (go = '1') then |
if (start = '1') then |
nxt_state := st_start; |
icore_cmd := CMD_START; |
elsif (read = '1') then |
nxt_state := st_read; |
icore_cmd := CMD_READ; |
idcnt := "111"; |
else |
nxt_state := st_write; |
icore_cmd := CMD_WRITE; |
idcnt := "111"; |
iload := '1'; |
end if; |
end if; |
|
when st_start => |
if (core_ack = '1') then |
if (read = '1') then |
nxt_state := st_read; |
icore_cmd := CMD_READ; |
idcnt := "111"; |
else |
nxt_state := st_write; |
icore_cmd := CMD_WRITE; |
idcnt := "111"; |
iload := '1'; |
end if; |
end if; |
|
when st_write => |
if (core_ack = '1') then |
idcnt := dcnt -1; -- count down Data_counter |
icore_txd := sr(7); |
if (dcnt = 0) then |
nxt_state := st_ack; |
icore_cmd := CMD_READ; |
else |
ishift := '1'; |
-- icore_txd := sr(7); |
end if; |
end if; |
|
when st_read => |
if (core_ack = '1') then |
idcnt := dcnt -1; -- count down Data_counter |
ishift := '1'; |
if (dcnt = 0) then |
nxt_state := st_ack; |
icore_cmd := CMD_WRITE; |
icore_txd := ack_in; |
end if; |
end if; |
|
when st_ack => |
if (core_ack = '1') then |
-- generate command acknowledge signal |
ihost_ack := '1'; |
|
-- Perform an additional shift, needed for 'read' (store last received bit in shift register) |
ishift := '1'; |
|
-- check for stop; Should a STOP command be generated ? |
if (stop = '1') then |
nxt_state := st_stop; |
icore_cmd := CMD_STOP; |
else |
nxt_state := st_idle; |
icore_cmd := CMD_NOP; |
end if; |
end if; |
|
when st_stop => |
if (core_ack = '1') then |
nxt_state := st_idle; |
icore_cmd := CMD_NOP; |
end if; |
|
when others => -- illegal states |
nxt_state := st_idle; |
icore_cmd := CMD_NOP; |
end case; |
|
-- generate registers |
if (nReset = '0') then |
core_cmd <= CMD_NOP; |
core_txd <= '0'; |
|
shift <= '0'; |
ld <= '0'; |
|
dcnt <= "111"; |
host_ack <= '0'; |
|
state <= st_idle; |
elsif (clk'event and clk = '1') then |
if (ena = '1') then |
state <= nxt_state; |
|
dcnt <= idcnt; |
shift <= ishift; |
ld <= iload; |
|
core_cmd <= icore_cmd; |
core_txd <= icore_txd; |
|
host_ack <= ihost_ack; |
end if; |
end if; |
end process nxt_state_decoder; |
|
end block statemachine; |
|
end architecture structural; |
|
|
-- |
-- |
-- I2C Core |
-- |
-- Translate simple commands into SCL/SDA transitions |
-- Each command has 5 states, A/B/C/D/idle |
-- |
-- start: SCL ~~~~~~~~~~\____ |
-- SDA ~~~~~~~~\______ |
-- x | A | B | C | D | i |
-- |
-- repstart SCL ____/~~~~\___ |
-- SDA __/~~~\______ |
-- x | A | B | C | D | i |
-- |
-- stop SCL ____/~~~~~~~~ |
-- SDA ==\____/~~~~~ |
-- x | A | B | C | D | i |
-- |
--- write SCL ____/~~~~\____ |
-- SDA ==X=========X= |
-- x | A | B | C | D | i |
-- |
--- read SCL ____/~~~~\____ |
-- SDA XXXX=====XXXX |
-- x | A | B | C | D | i |
-- |
|
-- Timing: Normal mode Fast mode |
----------------------------------------------------------------- |
-- Fscl 100KHz 400KHz |
-- Th_scl 4.0us 0.6us High period of SCL |
-- Tl_scl 4.7us 1.3us Low period of SCL |
-- Tsu:sta 4.7us 0.6us setup time for a repeated start condition |
-- Tsu:sto 4.0us 0.6us setup time for a stop conditon |
-- Tbuf 4.7us 1.3us Bus free time between a stop and start condition |
-- |
|
library ieee; |
use ieee.std_logic_1164.all; |
use ieee.std_logic_arith.all; |
|
entity i2c_core is |
port ( |
clk : in std_logic; |
nReset : in std_logic; |
|
clk_cnt : in unsigned(7 downto 0); |
|
cmd : in std_logic_vector(2 downto 0); |
cmd_ack : out std_logic; |
busy : out std_logic; |
|
Din : in std_logic; |
Dout : out std_logic; |
|
SCL : inout std_logic; |
SDA : inout std_logic |
); |
end entity i2c_core; |
|
architecture structural of i2c_core is |
constant CMD_NOP : std_logic_vector(2 downto 0) := "000"; |
constant CMD_START : std_logic_vector(2 downto 0) := "010"; |
constant CMD_STOP : std_logic_vector(2 downto 0) := "011"; |
constant CMD_READ : std_logic_vector(2 downto 0) := "100"; |
constant CMD_WRITE : std_logic_vector(2 downto 0) := "101"; |
|
type cmds is (idle, start_a, start_b, start_c, start_d, stop_a, stop_b, stop_c, rd_a, rd_b, rd_c, rd_d, wr_a, wr_b, wr_c, wr_d); |
signal state : cmds; |
signal SDAo, SCLo : std_logic; |
signal txd : std_logic; |
signal clk_en, slave_wait :std_logic; |
signal cnt : unsigned(7 downto 0) := clk_cnt; |
begin |
-- whenever the slave is not ready it can delay the cycle by pulling SCL low |
slave_wait <= '1' when ((SCLo = '1') and (SCL = '0')) else '0'; |
|
-- generate clk enable signal |
gen_clken: process(clk, nReset) |
begin |
if (nReset = '0') then |
cnt <= (others => '0'); |
clk_en <= '1'; --'0'; |
elsif (clk'event and clk = '1') then |
if (cnt = 0) then |
clk_en <= '1'; |
cnt <= clk_cnt; |
else |
if (slave_wait = '0') then |
cnt <= cnt -1; |
end if; |
clk_en <= '0'; |
end if; |
end if; |
end process gen_clken; |
|
-- generate statemachine |
nxt_state_decoder : process (clk, nReset, state, cmd, SDA) |
variable nxt_state : cmds; |
variable icmd_ack, ibusy, store_sda : std_logic; |
variable itxd : std_logic; |
begin |
|
nxt_state := state; |
|
icmd_ack := '0'; -- default no acknowledge |
ibusy := '1'; -- default busy |
|
store_sda := '0'; |
|
itxd := txd; |
|
case (state) is |
-- idle |
when idle => |
case cmd is |
when CMD_START => |
nxt_state := start_a; |
icmd_ack := '1'; -- command completed |
|
when CMD_STOP => |
nxt_state := stop_a; |
icmd_ack := '1'; -- command completed |
|
when CMD_WRITE => |
nxt_state := wr_a; |
icmd_ack := '1'; -- command completed |
itxd := Din; |
|
when CMD_READ => |
nxt_state := rd_a; |
icmd_ack := '1'; -- command completed |
|
when others => |
nxt_state := idle; |
-- don't acknowledge NOP command icmd_ack := '1'; -- command completed |
ibusy := '0'; |
end case; |
|
-- start |
when start_a => |
nxt_state := start_b; |
|
when start_b => |
nxt_state := start_c; |
|
when start_c => |
nxt_state := start_d; |
|
when start_d => |
nxt_state := idle; |
ibusy := '0'; -- not busy when idle |
|
|
-- stop |
when stop_a => |
nxt_state := stop_b; |
|
when stop_b => |
nxt_state := stop_c; |
|
when stop_c => |
-- nxt_state := stop_d; |
|
-- when stop_d => |
nxt_state := idle; |
ibusy := '0'; -- not busy when idle |
|
-- read |
when rd_a => |
nxt_state := rd_b; |
|
when rd_b => |
nxt_state := rd_c; |
|
when rd_c => |
nxt_state := rd_d; |
store_sda := '1'; |
|
when rd_d => |
nxt_state := idle; |
ibusy := '0'; -- not busy when idle |
|
-- write |
when wr_a => |
nxt_state := wr_b; |
|
when wr_b => |
nxt_state := wr_c; |
|
when wr_c => |
nxt_state := wr_d; |
|
when wr_d => |
nxt_state := idle; |
ibusy := '0'; -- not busy when idle |
|
end case; |
|
-- generate regs |
if (nReset = '0') then |
state <= idle; |
cmd_ack <= '0'; |
busy <= '0'; |
txd <= '0'; |
Dout <= '0'; |
elsif (clk'event and clk = '1') then |
if (clk_en = '1') then |
state <= nxt_state; |
busy <= ibusy; |
|
txd <= itxd; |
if (store_sda = '1') then |
Dout <= SDA; |
end if; |
end if; |
|
cmd_ack <= icmd_ack and clk_en; |
end if; |
end process nxt_state_decoder; |
|
-- |
-- convert states to SCL and SDA signals |
-- |
output_decoder: process (clk, nReset, state) |
variable iscl, isda : std_logic; |
begin |
case (state) is |
when idle => |
iscl := SCLo; -- keep SCL in same state |
isda := SDA; -- keep SDA in same state |
|
-- start |
when start_a => |
iscl := SCLo; -- keep SCL in same state (for repeated start) |
isda := '1'; -- set SDA high |
|
when start_b => |
iscl := '1'; -- set SCL high |
isda := '1'; -- keep SDA high |
|
when start_c => |
iscl := '1'; -- keep SCL high |
isda := '0'; -- sel SDA low |
|
when start_d => |
iscl := '0'; -- set SCL low |
isda := '0'; -- keep SDA low |
|
-- stop |
when stop_a => |
iscl := '0'; -- keep SCL disabled |
isda := '0'; -- set SDA low |
|
when stop_b => |
iscl := '1'; -- set SCL high |
isda := '0'; -- keep SDA low |
|
when stop_c => |
iscl := '1'; -- keep SCL high |
isda := '1'; -- set SDA high |
|
-- write |
when wr_a => |
iscl := '0'; -- keep SCL low |
-- isda := txd; -- set SDA |
isda := Din; |
|
when wr_b => |
iscl := '1'; -- set SCL high |
-- isda := txd; -- set SDA |
isda := Din; |
|
when wr_c => |
iscl := '1'; -- keep SCL high |
-- isda := txd; -- set SDA |
isda := Din; |
|
when wr_d => |
iscl := '0'; -- set SCL low |
-- isda := txd; -- set SDA |
isda := Din; |
|
-- read |
when rd_a => |
iscl := '0'; -- keep SCL low |
isda := '1'; -- tri-state SDA |
|
when rd_b => |
iscl := '1'; -- set SCL high |
isda := '1'; -- tri-state SDA |
|
when rd_c => |
iscl := '1'; -- keep SCL high |
isda := '1'; -- tri-state SDA |
|
when rd_d => |
iscl := '0'; -- set SCL low |
isda := '1'; -- tri-state SDA |
end case; |
|
-- generate registers |
if (nReset = '0') then |
SCLo <= '1'; |
SDAo <= '1'; |
elsif (clk'event and clk = '1') then |
if (clk_en = '1') then |
SCLo <= iscl; |
SDAo <= isda; |
end if; |
end if; |
end process output_decoder; |
|
SCL <= '0' when (SCLo = '0') else 'Z'; -- since SCL is externally pulled-up convert a '1' to a 'Z'(tri-state) |
SDA <= '0' when (SDAo = '0') else 'Z'; -- since SDA is externally pulled-up convert a '1' to a 'Z'(tri-state) |
-- SCL <= SCLo; |
-- SDA <= SDAo; |
|
end architecture structural; |
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