• asynchronous reset
• support multiple connected MAX7219 modules
• adjust brightness of the display of each module separately

1. Copy MAX7219.vhd and MAX7219_Pack.vhd files to your project location.
2. Import package MAX7219_Pack

use work.MAX7219_Pack.all;

3. Use component definition as below

component MAX7219
    generic (
        Devices   : positive;
        Intensity : MAX7219ConfigIntensity_t
    );
    port (
        clk         : in std_logic;
        reset_n     : in std_logic;
        data_vector : in std_logic_vector;
        clk_out     : out std_logic;
        data_out    : out std_logic;
        load_out    : out std_logic
    );
end component;

4. Create instance of the MAX7219 component. For example to support 2 modules:

• set devices to 2
• set displays brightness to values: 16#1# for the first and 16#3# for the second module.

instance: MAX7219
    generic map(
            devices => 2,
            intensity => (16#1#, 16#3#)
        )
    port map (
            clk => clock,
            data_vector => x"FEDCBA9876543210",
            clk_out => MAX7219_CLK,
            data_out => MAX7219_DATA,
            load_out => MAX7219_LOAD,
            reset_n => globalResetN
        );

Tip: data_vector length is equal 32 * Devices.

Some kind of modules has a build-in reverse voltage protection circuit. In most cases it is a popular 1N4148 silicon diode connected serially with VCC. You must remember that each diode of this thype in circuit decrease supply voltage about 0.7V. So if a first module is supply with 5V then supply voltage for the second module will about 4.3V only.

You can omit this issue in few ways:

1. Make supply voltage for all modules from the same path.
2. Replace diode with a P-channel MOSFET as below

• in my module I use IRLML6402TRPBF P-Channel transistor.

3. If you don't need reverse voltage protection in your module simple replace diode with wire.