I have some troubles with my nexys 3 vhdl driver for the Pmod TMP. I would like to communicate with via SPI 3 wire (Clock, Reset and DQ (MISO/MOSI)) so I've wrote some code lines and test it using the leds to display receive data. But That don't work and I don't know why... I've made a state machine that, if it's the first time, send the configuration data and then send the word "start" to start convert, then I pass in receive configuration and take the convert data (temperature in binary) and finally send the "stop" word. And that start again without the send configuration because it's not the first time.
My state machine don't work, there is not receive data and I don't know why.
I'll be glad if you could help me.
Best regards.
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.NUMERIC_STD.ALL;
entity SPI is
port(
CLK : in std_logic;
RST : in std_logic;
SPI_SCK : out std_logic;
SPI_DQ: inout std_logic;
SPI_RST : out std_logic;
LED : out std_logic_vector(7 downto 0) :="00000000"
);
end entity SPI;
architecture behavioral of SPI is
type State is ( IDLE , sendConf, sendBit , receiveBit, clockHigh , resetHigh);
signal States : State := IDLE;
signal Counter : integer range 0 to 15 := 0;
signal data_reg : std_logic_vector(15 downto 0):="0000000000000000";
signal data : std_logic_vector(8 downto 0):="000000000";
signal data_trans : std_logic_vector(7 downto 0):="00000000";
signal first_time : std_logic := '1';
signal send : std_logic := '0';
signal receive : std_logic := '0';
signal right : std_logic := '0';
begin
process(CLK, RST)
variable conf : std_logic_vector(15 downto 0):= "0000110000000011";
variable start: std_logic_vector(7 downto 0):= "01010001";
variable stop : std_logic_vector(7 downto 0):= "00100010";
begin
if rising_edge(CLK) then
if RST = '1' then
States <= IDLE;
first_time <= '1';
else
case States is
when IDLE =>
SPI_RST <= '1';
SPI_SCK <= '0';
Counter <= 0;
if first_time = '1' then
data_reg <= conf;
send <= '1';
first_time <= '0';
States <= sendConf;
else
if send = '1' then
data_trans <= start;
send <= '0';
receive <= '1';
right <= '0';
States <= sendBit;
elsif receive = '1' then
receive <= '0';
right <= '1';
States <= receiveBit;
elsif send = '0' and receive = '0' then
data_trans <= stop;
send <= '1';
right <= '0';
States <= sendBit;
end if;
end if;
when sendConf =>
SPI_SCK <= '0';
SPI_DQ <= data_reg(15);
data_reg <= data_reg(14 downto 0) & "0";
States <= clockHigh;
when sendBit =>
SPI_SCK <= '0';
SPI_DQ <= data_trans(7);
data_trans <= data_trans(6 downto 0) & "0";
States <= clockHigh;
when receiveBit =>
SPI_SCK <= '0';
data <= data(7 downto 0) & SPI_DQ;
States <= clockHigh;
when clockHigh =>
SPI_SCK <= '1';
if first_time = '1' then
if Counter = 16 then
States <= resetHigh;
else
Counter <= Counter + 1;
States <= sendConf;
end if;
else
if right = '1' then
if Counter = 9 then
States <= resetHigh;
else
Counter <= Counter + 1;
States <= sendBit;
end if;
else
if Counter = 8 then
States <= resetHigh;
else
Counter <= Counter + 1;
States <= sendBit;
end if;
end if;
end if;
when resetHigh =>
SPI_RST <= '0';
States <= IDLE;
end case;
end if;
end if;
end process;
end architecture behavioral;`
