Hello,
I am trying to write a PID controller with a state machine. It is working but I think it is not working properly.
I think there is a signed unsigned number or type conversion problem. Please, could you fixed it for me?
Is there any problem? When I tried the following algorithm in microblaze in C language, the PID module working properly.
With best regeards,
entity PIDModule is
Port ( ADC_DATA : in STD_LOGIC_VECTOR (15 downto 0); --16 bit unsigned PID input
DAC_DATA : out STD_LOGIC_VECTOR (15 downto 0); --16 bit unsigned PID output
CLK1 : in STD_LOGIC;
);
end PIDModule;
architecture Behavioral of PIDModule is
type statetypes is (Reset,
CalculateNewError,
CalculatePID,
DivideKg,
Write2DAC,
SOverload,
ConvDac
);
signal state,next_state : statetypes := Reset;
signal Kp : integer := 10;
signal Kd : integer :=20;
signal Ki : integer :=1;
signal Kg : integer := 256;
signal Output : integer := 1;
signal SetVal : integer := 33259;
signal sAdc : integer := 0 ;
signal Error: integer := 0;
signal p,i,d : integer := 0;
signal DacDataCarrier : std_logic_vector (15 downto 0);
signal AdcDataCarrier : std_logic_vector (15 downto 0);
begin
PROCESS
variable Output_Old : integer := 0;
variable Error_Old : integer := 0;
BEGIN
IF CLK1'EVENT AND CLK1='1' THEN
state <= next_state;
END IF;
case state is
when Reset =>
sAdc <= conv_integer(ADC_DATA); --Get the input for PID
next_state <= CalculateNewError;
Error_Old := Error; --Capture old error
Output_Old := Output; --Capture old PID output
when CalculateNewError => --
next_state <= CalculatePID;
Error <= (SetVal-sAdc); --Calculate Error
when CalculatePID =>
next_state <= DivideKg;
p <= Kp*(Error); --Calculate PID
i <= Ki*(Error+Error_Old);
d <= Kd *(Error-Error_Old);
when DivideKg =>
next_state <= SOverload;
Output <= Output_Old+(p+i+d)/2048; --Calculate new output
when SOverload =>
next_state <=ConvDac;
if Output > 65535 then
Output <= 65535 ;
end if;
if Output < 1 then
Output <= 1;
end if;
when ConvDac =>
--Send the output to port
DacDataCarrier <= conv_std_logic_vector(Output ,16);
next_state <=Write2DAC;
when Write2DAC =>
next_state <= Reset;
DAC_DATA <= DacDataCarrier;
end case;
END IF;
END PROCESS;
end Behavioral;
