Subversion Repositories single-14-segment-display-driver-w-decoder

--------------------------------------------------------------------------------

-- Entity: display_driver_w_decoder

-- Date:2017-01-06  

-- Author: GL     

--

-- Description: Top module for display driver with decoder

--! @file

--! @brief Display Driver With Decoder Top Level Module

--------------------------------------------------------------------------------

library ieee;

use ieee.std_logic_1164.all;

use ieee.numeric_std.all;

--! @brief Top entity of the display driver.

--! @details Top entity of the decoder architecture. Module description also goes here.

entity display_driver_w_decoder is

        port  (

        clk     : in    std_logic;                                      --! input clock, xx MHz.

        reset   : in    std_logic;                                      --! active high

        ascii_in: in    std_logic_vector(7 downto 0);                   --! input ASCII code to display

        wr_en   : in    std_logic;                                      --! active high write enable to store the ASCII code in a register

        --! Typically the data fed to display (single or multiple) is provided for single display at a time.

        --! If multiple displays are required disp_sel signal must be provided (according typical dynamic display indication).

        --! 

        --! \section disp_data_bit_mapping Display Segment Bit Mapping

        --! |Bit Number     |   14|   13|   12|   11|   10|    9|    8|    7|    6|    5|    4|    3|    2|    1|0    |

        --! |:--------:     |:---:|:---:|:---:|:---:|:---:|:---:|:---:|:---:|:---:|:---:|:---:|:---:|:---:|:---:|:---:|

        --! |Display Segment|   dp|    m|    l|    k|    j|    i|    h|   g2|   g1|    f|    e|    d|    c|    b|a    |

        --! Note that there is no standard way to name the segments. 

        --! Current data bits correspondt to display segments according this picture: @image html https://www.maximintegrated.com/en/images/appnotes/3211/3211Fig02.gif

        disp_data_q : out std_logic_vector(14 downto 0);

        --! If more displays needs to be fed change disp_sel to vector with length equal to number of displays.

        --! Use principles of the standard dynamic indication: provide data then enable the displays sequentially.

        --! If brightness control is desired just AND the selector and the PWM controller output.

        disp_sel  : out std_logic

        );

end display_driver_w_decoder;

--! @brief Architecture definition of the display_driver_w_decoder

--! @details Architecture describes the structure of the module together with doxygen description for doumentation generatior

architecture display_driver_w_decoder_arch of display_driver_w_decoder is

    signal ascii_reg: std_logic_vector(7 downto 0);

    attribute syn_noprune: boolean;

    attribute syn_noprune of ascii_reg: signal is true;

begin

    --! \mainpage 14-segment Display Driver Info

    --!

    --! \section intro_sec Introduction

    --!

    --! The main purpose of this module is to be fed with ASCI symbol codes and it will output word lighting up the exact segments 

    --! on the 14-segment display to visualize the ASCII character. Current implementation uses input register to store the input code. 

    --!

    --! ASCII symbols are coded in Byte having values from 0x00 to 0x7F. This range covers all the symbols in the decoding table.

    --! The range is doubled because the symbols may be lit with DP on or off. More information may be found in MAX6955 datasheet.

    --! Follows small revised quote of the most descriptive part related to decoding. Not applicable words are removed.

    --!

    --! ... includes 104-character ASCII font maps for 14-segment... . The characters follow the standard ASCII font, with the

    --! addition of the following common symbols: GBP, EUR, Yen, degree, micro, plus/minus, arrow up, and arrow down. 

    --! Seven bits represent the 104-character font map; an 8th bit is used to select whether the decimal point (DP) is lit.

    --! source: https://datasheets.maximintegrated.com/en/ds/MAX6955.pdf

    --!

    --! \section port_disp_data Display Data Out

    --!

    --! Typically the data fed to display (single or multiple) is provided for single display at a time.

    --! If multiple displays are required disp_sel signal must be provided (according typical dynamic display indication) to determine

    --! for which display is the data targeted.

    --! 

    --! \subsection disp_data_bit_mapping Display Segment Bit Mapping

    --! |Bit Number     |   14|   13|   12|   11|   10|    9|    8|    7|    6|    5|    4|    3|    2|    1|0    |

    --! |:--------:     |:---:|:---:|:---:|:---:|:---:|:---:|:---:|:---:|:---:|:---:|:---:|:---:|:---:|:---:|:---:|

    --! |Display Segment|   dp|    m|    l|    k|    j|    i|    h|   g2|   g1|    f|    e|    d|    c|    b|a    |

    --! Note that there is no standard way to name the segments. 

    --! Current data bits correspondt to display segments according this picture: @image html https://www.maximintegrated.com/en/images/appnotes/3211/3211Fig02.gif

    ascii_decoder_module:entity work.ASCIIDecoder

    port map(

        clk         => clk,

        reset       => reset,

        ascii_in    => ascii_in,

        disp_data_q => disp_data_q

    );

    disp_sel <= '0';                                                    -- TODO: implement this correctly

end display_driver_w_decoder_arch;