Comparison Arduino, VHDP and VHDL

Sequential Example

Arduino

#define LED 13 void setup() {  pinMode(LED, OUTPUT);         //Declare output} void loop() {                   //Procedural programming  digitalWrite(LED, HIGH);      //LED on  delay(1000);                  //Wait  digitalWrite(LED, LOW);       //LED off  delay(1000);                  //Wait}

VHDP

Main (  LED : OUT STD_LOGIC;        --Declare output){    Process() {                 --For parallel and procedural programming        Thread {                  --Procedural programming            LED <= '1';               --LED on            Wait(1000ms);             --Wait            LED <= '0';             --LED off            Wait(1000ms);             --Wait        }    }}

Generated VHDL

library IEEE;use IEEE.STD_LOGIC_1164.ALL;use IEEE.numeric_std.all;  ENTITY Blink ISPORT (  CLK : IN STD_LOGIC;  LED : OUT STD_LOGIC           --Declare output);END Blink; ARCHITECTURE BEHAVIORAL OF Blink ISBEGIN   PROCESS (CLK)      VARIABLE Thread3 : NATURAL range 0 to 24000004 := 0;  BEGIN  IF RISING_EDGE(CLK) THEN    CASE (Thread3) IS                   --Created state machine      WHEN 0 =>        LED <= '1';                     --LED on        Thread3 := 1;      WHEN 1 to 12000001 =>             Thread3 := Thread3 + 1;         --Wait      WHEN 12000002 =>        LED <= '0';                     --LED off        Thread3 := 12000003;      WHEN 12000003 to 24000003 =>        IF (Thread3 < 24000003) THEN           Thread3 := Thread3 + 1;       --Wait        ELSE          Thread3 := 0;                 END IF;      WHEN others => Thread3 := 0;    END CASE;  END IF;  END PROCESS;  END BEHAVIORAL;

Parallel Calculation Example (+ VARIABLE vs SIGNAL)

Not possible with Arduino

Can't be compared because Arduino doesn't support parallel programming. You can't have multiple parallel processes for different tasks and calculations are much slower because one operation can take more than one clock cycle. If you have multiple operations together (like "(Xi / 10) + 5"), every operation increases the time after calculation is finished.

VHDP

Main (    Xi : IN  INTEGER range 0 to 255;    --Declare inputs    Yi : IN  INTEGER range 0 to 255;          Xo : OUT INTEGER range 0 to 255;    --Declare output    Yo : OUT INTEGER range 0 to 255;    ){    Process() {                         --For parallel and procedural programming        Xo <= (Xi / 10) + 5;            --Everything calculated in one clock cycle        Yo <= (Yi / 5) + 10;            --Second calculation is finished together with first                SIGNAL   i1 : INTEGER := 0;     --Create integer signal (takes value one cycle after assignment)        VARIABLE i2 : INTEGER := 0;     --Create integer variable (takes value immediately, but can only be used in this process)        i1 <= i1 + 1;                   --Add both + 1        i2 := i2 + 1;                If(i1 > 0){                     --The signal is still 0, so this is false            i1 <= i1 - 1;        }        If(i2 > 0){                     --The variable is 1 already            i2 := i2 - 1;        }    }}

Generated VHDL

library IEEE;use IEEE.STD_LOGIC_1164.ALL;use IEEE.numeric_std.all; use work.String_Type_Package.all; ENTITY Blink ISPORT (  CLK : IN STD_LOGIC;    Xi : IN  INTEGER range 0 to 255;      --Declare inputs  Yi : IN  INTEGER range 0 to 255;  Xo : OUT INTEGER range 0 to 255;      --Declare output  Yo : OUT INTEGER range 0 to 255);END Blink; ARCHITECTURE BEHAVIORAL OF Blink IS  SIGNAL   i1 : INTEGER := 0;BEGIN   PROCESS (CLK)    VARIABLE i2 : INTEGER := 0;  BEGIN  IF RISING_EDGE(CLK) THEN    Xo <= (Xi / 10) + 5;                --Code in "Process" is converted 1:1 into VHDL    Yo <= (Yi / 5) + 10;                     i1 <= i1 + 1;                       i2 := i2 + 1;     IF (i1 > 0) THEN                    --Also if you use if, case, for or while      i1 <= i1 - 1;    END IF;     IF (i2 > 0) THEN      i2 := i2 - 1;    END IF;  END IF;  END PROCESS;  END BEHAVIORAL;

Parallel Process Example

This is a simple code for an ultrasonic-sensor

VHDP

Main (    US_Trigger : OUT STD_LOGIC := '0';    US_Echo    : IN  STD_LOGIC := '0'; ){    Process Trigger_Process () {        --Creates an impuls every ~100ms to trigger the distance measurement        Thread {            US_Trigger <= '1';            Wait(10us);            US_Trigger <= '0';            Wait(100ms);        }    }        Process Echo_Process () {        Thread {            --Waits for a new echo impuls to calculate the distance            While(US_Echo = '1'){}            While(US_Echo = '0'){}                --Counts the microseconds while the sound travels to the object and back            --58 microseconds = 1cm            For(VARIABLE d : INTEGER := 0; US_Echo = '1'; d := d + 1) {                Wait(58us);            }            --d is now the distance to the object in cm        }    }}

Generated VHDL

library IEEE;use IEEE.STD_LOGIC_1164.ALL;use IEEE.numeric_std.all;  ENTITY Blink ISPORT (  CLK : IN STD_LOGIC;    US_Trigger : OUT STD_LOGIC := '0';  US_Echo    : IN  STD_LOGIC := '0');END Blink; ARCHITECTURE BEHAVIORAL OF Blink IS  BEGIN   Trigger_Process : PROCESS (CLK)      VARIABLE Thread3 : NATURAL range 0 to 1200124 := 0;  BEGIN  IF RISING_EDGE(CLK) THEN    CASE (Thread3) IS      WHEN 0 =>        US_Trigger <= '1';        Thread3 := 1;      WHEN 1 to 121 =>        Thread3 := Thread3 + 1;      WHEN 122 =>        US_Trigger <= '1';        Thread3 := 123;      WHEN 123 to 1200123 =>        IF (Thread3 < 1200123) THEN           Thread3 := Thread3 + 1;        ELSE          Thread3 := 0;        END IF;      WHEN others => Thread3 := 0;    END CASE;  END IF;  END PROCESS;    Echo_Process : PROCESS (CLK)      VARIABLE d : INTEGER := 0;    VARIABLE Thread9 : NATURAL range 0 to 4 := 0;    VARIABLE Thread14 : NATURAL range 0 to 698 := 0;  BEGIN  IF RISING_EDGE(CLK) THEN    CASE (Thread9) IS      WHEN 0 =>        IF (US_Echo = '1') THEN        ELSE          Thread9 := Thread9 + 1;        END IF;      WHEN 1 =>        IF (US_Echo = '0') THEN        ELSE          Thread9 := Thread9 + 1;        END IF;      WHEN 2 =>        d := 0;        Thread9 := 3;      WHEN 3 =>        IF ( US_Echo = '1') THEN           Thread9 := Thread9 + 1;        ELSE          Thread9 := 0;        END IF;      WHEN (3+1) =>        CASE (Thread14) IS          WHEN 0 to 696 =>            Thread14 := Thread14 + 1;          WHEN 697 =>            d := d + 1;            Thread9 := 3;            Thread14 := 0;          WHEN others => Thread14 := 0;        END CASE;      WHEN others => Thread9 := 0;    END CASE;  END IF;  END PROCESS;  END BEHAVIORAL;

Parallel Component Example

In the libraries you can find Components that form an interface for different hardware. You can find controller for ultrasonic-sensors or for UART data (like Serial in Arduino). Every NewComponent runs in parallel, so you can add as many UART ports as you need.

VHDP

Main (    US_Trigger : OUT STD_LOGIC_VECTOR(7 downto 0) := '0';   --8 ultrasonic sensors    US_Echo    : IN  STD_LOGIC_VECTOR(7 downto 0) := '0';        LED        : OUT STD_LOGIC;                             --1 LED to show distance with brightness){    TYPE Distance_type IS ARRAY (0 to 7) OF NATURAL range 0 to 255;    SIGNAL Distance : Distance_type;                        --Distances of the 8 sensors        Generate (for i in 0 to 7) {                            --Generate an controller for every ultrasonic-sensor        NewComponent Ultrasonic_Controller (            Update_Frequency => 15,                         --Checks 15 times in a second            Trigger          => US_Trigger(i),            Echo             => US_Echo(i),            Dist             => Distance(i),        );    }        --Convert number from 0 to 255 to a 8-bit bit vector    PWM_Generator_Duty <= STD_LOGIC_VECTOR(TO_UNSIGNED(Distance(0), PWM_Generator_Duty'LENGTH));        SIGNAL PWM_Generator_Duty : STD_LOGIC_VECTOR (7 DOWNTO 0);    NewComponent PWM_Generator (                            --Outputs distance of first sensor        Duty            => PWM_Generator_Duty,        PWM_Out(0)      => LED,    );}

Generated VHDL

library IEEE;use IEEE.STD_LOGIC_1164.ALL;use IEEE.numeric_std.all;  ENTITY Blink ISPORT (  CLK : IN STD_LOGIC;    US_Trigger : OUT STD_LOGIC_VECTOR(7 downto 0) := '0';     US_Echo    : IN  STD_LOGIC_VECTOR(7 downto 0) := '0';  LED        : OUT STD_LOGIC         );END Blink; ARCHITECTURE BEHAVIORAL OF Blink IS   TYPE Distance_type IS ARRAY (0 to 7) OF NATURAL range 0 to 255;  SIGNAL Distance : Distance_type;  SIGNAL PWM_Generator_Duty            : STD_LOGIC_VECTOR (7 DOWNTO 0);    COMPONENT Ultrasonic_Controller IS  GENERIC (    CLK_Frequency       : NATURAL := 12000000;          Update_Frequency    : NATURAL := 15        );  PORT (    CLK : IN STD_LOGIC;    Reset   : IN  STD_LOGIC := '0';                 Trigger : OUT STD_LOGIC := '0';                 Echo    : IN  STD_LOGIC := '0';                 Dist    : OUT NATURAL range 0 to 1000 := 0   );  END COMPONENT;    COMPONENT PWM_Generator IS  GENERIC (    CLK_Frequency   : INTEGER := 12000000;       PWM_Frequency   : INTEGER := 100000;         Bits_Resolution : INTEGER := 8;              Phases          : INTEGER := 1     );  PORT (    CLK : IN STD_LOGIC;    Reset     : IN  STD_LOGIC := '0';                                 Enable    : IN  STD_LOGIC := '1';                                 Duty      : IN  STD_LOGIC_VECTOR(Bits_Resolution-1 DOWNTO 0) := (others => '0');     PWM_Out   : OUT STD_LOGIC_VECTOR(Phases-1 DOWNTO 0) := (others => '0')     );  END COMPONENT;  BEGIN   PWM_Generator_Duty <= STD_LOGIC_VECTOR(TO_UNSIGNED(Distance(0), PWM_Generator_Duty'LENGTH));    Generate1 : for i in 0 to 7 GENERATE    Ultrasonic_Controller1 : Ultrasonic_Controller    GENERIC MAP (      Update_Frequency => 15           ) PORT MAP (      CLK => CLK,      Trigger          => US_Trigger(i),      Echo             => US_Echo(i),      Dist             => Distance(i)    );  END GENERATE Generate1;    PWM_Generator1 : PWM_Generator  PORT MAP (    CLK => CLK,    Duty            => PWM_Generator_Duty,    PWM_Out(0)      => LED  );  END BEHAVIORAL;

String Example

Arduino

void setup() {  Serial.begin(9600);               //Start UART with Baudrate = 9600} void loop() {  Serial.println("Hello World");    //Send "Hello World" string  delay(2000);                      //Wait}

VHDP

Main (    RX : IN  STD_LOGIC;             --I/Os for USB to UART converter    TX : OUT STD_LOGIC;){    Process () {        Thread {                    --Procedural programming            --Create constant string "Hello World!" (Adds RAM and interface for the stored string)            NewFunction assignString (s"Hello World!", hwStr);             --Output string with UART component below            NewFunction printString (hwStr, UART_Interface_TX_Data, UART_Interface_TX_Busy, UART_Interface_TX_Enable);             Wait(2000ms);           --Wait        }    }        SIGNAL UART_Interface_TX_Enable     : STD_LOGIC;    SIGNAL UART_Interface_TX_Busy       : STD_LOGIC;    SIGNAL UART_Interface_TX_Data       : STD_LOGIC_VECTOR (7 DOWNTO 0);        NewComponent UART_Interface     --Add a UART interface (You can add as many as needed)    (        Baud_Rate     => 9600,      --Set Baudrate = 9600                RX            => RX,        TX            => TX,        TX_Enable     => UART_Interface_TX_Enable,        TX_Busy       => UART_Interface_TX_Busy,        TX_Data       => UART_Interface_TX_Data,    );}

Generated VHDL

library IEEE;use IEEE.STD_LOGIC_1164.ALL;use IEEE.numeric_std.all; use work.String_Type_Package.all; ENTITY Blink IS PORT (  CLK : IN STD_LOGIC;    RX : IN  STD_LOGIC;               TX : OUT STD_LOGIC);END Blink; ARCHITECTURE BEHAVIORAL OF Blink IS   SIGNAL UART_Interface_TX_Enable     : STD_LOGIC;  SIGNAL UART_Interface_TX_Busy       : STD_LOGIC;  SIGNAL UART_Interface_TX_Data       : STD_LOGIC_VECTOR (7 DOWNTO 0);  SIGNAL hwStr                        : String_Type;   COMPONENT Single_Port_ROM IS  GENERIC (      Data    : STD_LOGIC_VECTOR := x"524f4d204578616d706c65"  );  PORT (    CLK : IN STD_LOGIC;    Length   : OUT NATURAL := Data'LENGTH/8;    Address  : in  natural range 0 to Data'LENGTH/8-1;    Data_OUT : out std_logic_vector(7 downto 0)  );  END COMPONENT;   COMPONENT UART_Interface IS  GENERIC (    CLK_Frequency   :   INTEGER     := 12000000;        Baud_Rate       :   INTEGER     := 19200;           OS_Rate         :   INTEGER     := 16;              D_Width         :   INTEGER     := 8;               Parity          :   INTEGER     := 0;               Parity_EO       :   STD_LOGIC   := '0'  );  PORT (    CLK : IN STD_LOGIC;    Reset       : IN    STD_LOGIC := '0';                           RX          : IN    STD_LOGIC := '1';                           TX          : OUT   STD_LOGIC := '1';                           TX_Enable   : IN    STD_LOGIC := '0';                           TX_Busy     : OUT   STD_LOGIC := '0';                           TX_Data     : IN    STD_LOGIC_VECTOR(D_Width-1 DOWNTO 0) := (others => '0');        RX_Busy     : OUT   STD_LOGIC := '0';                           RX_Data     : OUT   STD_LOGIC_VECTOR(D_Width-1 DOWNTO 0) := (others => '0');        RX_Error    : OUT   STD_LOGIC := '0'  );  END COMPONENT;  BEGIN   Single_Port_ROM1 : Single_Port_ROM  GENERIC MAP (      Data     => x"48656c6c6f20576f726c6421"       --constant "Hello World!" string  ) PORT MAP (    CLK => CLK,    Length   => hwStr.Length,    Address  => hwStr.Address,    Data_OUT => hwStr.Data_OUT  );   PROCESS (CLK)      VARIABLE printString_i : NATURAL := 0;    VARIABLE Thread4 : NATURAL range 0 to 24000004 := 0;    VARIABLE Thread7 : NATURAL range 0 to 6 := 0;  BEGIN  IF RISING_EDGE(CLK) THEN    CASE (Thread4) IS      WHEN 0 =>        printString_i := 0;        Thread4 := 1;      WHEN 1 =>        IF ( printString_i < hwStr.Length) THEN     --Sends chars one by one out of ROM          Thread4 := Thread4 + 1;        ELSE          Thread4 := Thread4 + 2;        END IF;      WHEN (1+1) =>        CASE (Thread7) IS          WHEN 0 =>            hwStr.Address <= printString_i;            Thread7 := 1;          WHEN 1 =>            tx_data <= hwStr.Data_OUT;            UART_Interface_TX_Enable <= '1';            Thread7 := 2;          WHEN 2 =>            IF (tx_busy = '0') THEN            ELSE              Thread7 := Thread7 + 1;            END IF;          WHEN 3 =>            UART_Interface_TX_Enable <= '0';            Thread7 := 4;          WHEN 4 =>            IF (tx_busy = '1') THEN            ELSE              Thread7 := Thread7 + 1;            END IF;          WHEN 5 =>            printString_i := printString_i + 1;            Thread7 := 0;            Thread4 := 1;          WHEN others => Thread7 := 0;        END CASE;      WHEN 3 to 24000003 =>                         --Wait        IF (Thread4 < 24000003) THEN           Thread4 := Thread4 + 1;        ELSE          Thread4 := 0;        END IF;      WHEN others => Thread4 := 0;    END CASE;  END IF;  END PROCESS;   UART_Interface1 : UART_Interface      --Add a UART interface (You can add as many as needed)  GENERIC MAP (      Baud_Rate   => 9600               --Set Baudrate = 9600  ) PORT MAP (    CLK           => CLK,    RX            => RX,    TX            => TX,    TX_Enable     => UART_Interface_TX_Enable,    TX_Busy       => UART_Interface_TX_Busy,    TX_Data       => UART_Interface_TX_Data  );  END BEHAVIORAL;

Loop Example

Arduino

void loop() {  //Only has sequential loops  for (int i = 0; i < 10; i ++){    //Turn LEDs 0-9 on    digitalWrite(i, HIGH);  }  delay(1000);              //Wait  int i = 0;  while (i < 10){           //Turn LEDs 0-9 off    digitalWrite(i, LOW);    i ++;  }  delay(1000);              //Wait}

VHDP

Main (    LEDs_par : OUT STD_LOGIC_VECTOR(0 to 9);    LEDs_seq : OUT STD_LOGIC_VECTOR(0 to 9);){    Process() {                         --For parallel and procedural programming        For(i IN 0 to 9) {              --Turn every led on in the first clock cycle            LEDs_par(i) <= '1';         --LEDs_par <= (others => '1'); does the same        }                Thread {                        --Same program as Arduino program            For(VARIABLE i : INTEGER := 0; i < 10; i := i + 1) {                LEDs_seq(i) <= '1';     --Turn LEDs 0-9 on            }            Wait(1000ms);               --Wait            i := 0;            While(i < 10) {             --Turn LEDs 0-9 off                LEDs_seq(i) <= '0';                i := i + 1;            }            Wait(1000ms);               --Wait        }    }}

Generated VHDL

library IEEE;use IEEE.STD_LOGIC_1164.ALL;use IEEE.numeric_std.all;  ENTITY Blink ISPORT (  CLK : IN STD_LOGIC;    LEDs_par : OUT STD_LOGIC_VECTOR(0 to 9);  LEDs_seq : OUT STD_LOGIC_VECTOR(0 to 9));END Blink; ARCHITECTURE BEHAVIORAL OF Blink IS  BEGIN   PROCESS (CLK)      VARIABLE i : INTEGER := 0;    VARIABLE Thread4 : NATURAL range 0 to 24000006 := 0;  BEGIN  IF RISING_EDGE(CLK) THEN    FOR i IN 0 to 9 LOOP      LEDs_par(i) <= '1';    END LOOP;    CASE (Thread4) IS      WHEN 0 =>        i := 0;        Thread4 := 1;      WHEN 1 =>        IF ( i < 10) THEN           LEDs_seq(i) <= '1';          i := i + 1;        ELSE          Thread4 := Thread4 + 1;        END IF;      WHEN 2 to 12000002 =>        Thread4 := Thread4 + 1;      WHEN 12000003 =>        i := 0;        Thread4 := 12000004;      WHEN 12000004 =>        IF (i < 10) THEN           LEDs_seq(i) <= '0';          i := i + 1;        ELSE          Thread4 := Thread4 + 1;        END IF;      WHEN 12000005 to 24000005 =>        IF (Thread4 < 24000005) THEN           Thread4 := Thread4 + 1;        ELSE          Thread4 := 0;        END IF;      WHEN others => Thread4 := 0;    END CASE;  END IF;  END PROCESS;  END BEHAVIORAL;

Loop Comparison

The parallel For and While can be also be used in a Thread.

VHDP

Main (    LEDs : OUT STD_LOGIC_VECTOR(0 to 9);){    Process() {        Thread {            --Turn on LEDs 0-9 sequentially in 12 clock cycles (10 + 1 for start and end)            For(VARIABLE i : INTEGER := 0; i < 10; i := i + 1) {                LEDs(i) <= '1';             }            Wait(1000ms);       --Wait            --Turn on LEDs 0-9 parallely in 1 clock cycle            ParFor(i IN 0 to 9) {                       LEDs(i) <= '1';                 }            Wait(1000ms);       --Wait        }    }}

Generated VHDL

library IEEE;use IEEE.STD_LOGIC_1164.ALL;use IEEE.numeric_std.all;       ENTITY Blink ISPORT (  CLK : IN STD_LOGIC;    LEDs : OUT STD_LOGIC_VECTOR(0 to 9));END Blink; ARCHITECTURE BEHAVIORAL OF Blink IS  BEGIN   PROCESS (CLK)      VARIABLE i : INTEGER := 0;    VARIABLE Thread3 : NATURAL range 0 to 24000005 := 0;  BEGIN  IF RISING_EDGE(CLK) THEN    CASE (Thread3) IS      WHEN 0 =>        i := 0;        Thread3 := 1;      WHEN 1 =>        IF ( i < 10) THEN           LEDs(i) <= '1';          i := i + 1;        ELSE          Thread3 := Thread3 + 1;        END IF;      WHEN 2 to 12000002 =>        Thread3 := Thread3 + 1;      WHEN 12000003 =>        FOR i IN 0 to 9 LOOP          LEDs(i) <= '1';        END LOOP;        Thread3 := 12000004;      WHEN 12000004 to 24000004 =>        IF (Thread3 < 24000004) THEN           Thread3 := Thread3 + 1;        ELSE          Thread3 := 0;        END IF;      WHEN others => Thread3 := 0;    END CASE;  END IF;  END PROCESS;  END BEHAVIORAL;