bcm_rod_dp_updown_counter.bcm_rod_dp_updown_counter_arc Architecture Reference
up-down counter More...
Inheritance diagram for bcm_rod_dp_updown_counter.bcm_rod_dp_updown_counter_arc:
Collaboration diagram for bcm_rod_dp_updown_counter.bcm_rod_dp_updown_counter_arc:
Processes | |
| ram_fill_counter | ( CLK_2X ) |
Signals | |
| dp_ram_updown_counter | std_logic_vector ( 8 downto 0 ) := ( others = > ' 0 ' ) |
Detailed Description
up-down counterDefinition at line 55 of file bcm_rod_dp_updown_counter.vhd.
Member Function Documentation
| ram_fill_counter | ( CLK_2X ) |
counter for RAM fill pointer; 5 modes:
- count up
- count up, counter full
- count down
- count down, counter empty
- no count or up & down in same cycle
Definition at line 67 of file bcm_rod_dp_updown_counter.vhd.
00067 ram_fill_counter : process(CLK_2X) 00068 begin 00069 if (CLK_2X'event and CLK_2X = '1') then 00070 if (SCLR = '1') then -- synchronous clear (reset) 00071 dp_ram_updown_counter <= (others => '0'); 00072 busy <= '0'; 00073 data_available <= '0'; 00074 write_error <= '0'; 00075 read_error <= '0'; 00076 else 00077 if ((count_up = '1' and count_down = '0') or (count_up = '1' and count_down = '1' and CLK = '0')) then -- only counting up 00078 if (dp_ram_updown_counter = "111111111") then -- counter full - data could not be stored in RAM 00079 dp_ram_updown_counter <= dp_ram_updown_counter; 00080 write_error <= '1'; 00081 busy <= '1'; 00082 else -- counter not full - data could be stored in RAM 00083 dp_ram_updown_counter <= (dp_ram_updown_counter + "01"); 00084 write_error <= '0'; 00085 if (dp_ram_updown_counter >= "111111101") then 00086 busy <= '1'; 00087 else 00088 busy <= '0'; 00089 end if; 00090 end if; 00091 data_available <= '1'; 00092 read_error <= '0'; 00093 elsif (count_up = '0' and count_down = '1' and CLK = '1') then -- only counting down 00094 if (dp_ram_updown_counter = "000000000") then -- counter full - data could not be stored in RAM 00095 dp_ram_updown_counter <= dp_ram_updown_counter; 00096 read_error <= '1'; 00097 data_available <= '0'; 00098 else -- counter not full - data could be stored in RAM 00099 dp_ram_updown_counter <= (dp_ram_updown_counter - "01"); 00100 read_error <= '0'; 00101 if (dp_ram_updown_counter <= "000000001") then 00102 data_available <= '0'; 00103 else 00104 data_available <= '1'; 00105 end if; 00106 end if; 00107 write_error <= '0'; 00108 busy <= '0'; 00109 else -- counting up and down or no counting at all 00110 dp_ram_updown_counter <= dp_ram_updown_counter; 00111 if (count_down = '0') then 00112 read_error <= '0'; 00113 end if; 00114 if (dp_ram_updown_counter = "000000000") then 00115 data_available <= '0'; 00116 else 00117 data_available <= '1'; 00118 end if; 00119 if (dp_ram_updown_counter >= "111111110") then 00120 busy <= '1'; 00121 else 00122 busy <= '0'; 00123 end if; 00124 write_error <= '0'; 00125 end if; 00126 end if; 00127 end if; 00128 end process;
The documentation for this class was generated from the following file:
