ADM-XRC SDK 2.8.1 User Guide (Linux)
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PLXSIM VHDL reference - locbus_arb

Declaration

Synopsis

Description

Declaration
component locbus_arb
    generic(
        tco_p2p  : in    time := 5 ns;
        n_arb    : in    natural;
        priority : in    integer_vector_t);
    port(
        lreset_l : in    std_logic;
        lclk     : in    std_logic;
        lhold    : in    std_logic_vector(n_arb - 1 downto 0);
        lholda   : out   std_logic_vector(n_arb - 1 downto 0));
end component;
Synopsis

Non-synthesizable testbench component that performs access arbitration on the local bus.

Description

This component can be instantiated in a testbench to arbitrate between several local bus agents for access to the local bus. The arbitration scheme works as follows:

The generics should be mapped as follows:

Generic Map to...
tco_p2p A value of type time that represents the desired local bus clock-to-output delay for signals such as LDACK#). This parameter has a suitable default value so it need not be specified.
n_arb An integer whose value is the number of local bus agents in the testbench. This value is also the length of the vectors lhold and lholda, since there must be one pair of signals per local bus agent.
priority An integer vector (type integer_vector_t) that specifies the priorities for each local bus agent, where a numerically higher value represents higher priority. The length of this vector must be equal to n_arb.

The ports must be mapped to signals as follows:

Port Map to...
lclk A signal equivalent to the local bus clock LCLK
lhold A vector that carries the bus request signals for all of the local bus agents in the design. Each element of the vector corresponds to the HOLD signal for a particular local bus agent.
lholda A vector that carries the bus grant signals for all of the local bus agents in the design. Each element of the vector corresponds to the HOLDA signal for a particular local bus agent.
lreset_l A signal equivalent to the local bus signal LRESET#

 


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