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Diffstat (limited to 'hdl/PIC.vhd')
| -rw-r--r-- | hdl/PIC.vhd | 181 |
1 files changed, 181 insertions, 0 deletions
diff --git a/hdl/PIC.vhd b/hdl/PIC.vhd new file mode 100644 index 0000000..a31bec7 --- /dev/null +++ b/hdl/PIC.vhd @@ -0,0 +1,181 @@ +library ieee; +use ieee.std_logic_1164.all; +use ieee.numeric_std.all; +use work.alu_types.all; + +entity PIC is + generic ( + CLK_FREQ : positive := 50_000_000; -- 50M, GW5A clock + BAUD_RATE : positive := 115_200 + ); + port ( + clk : in std_logic; + reset : in std_logic; + opcode : in std_logic_vector(13 downto 0); + + program_counter : out std_logic_vector(12 downto 0) := (others => '0'); + instruction_return : out std_logic := '0'; + work_reg : out std_logic_vector(7 downto 0) := (others => '0'); + status : out std_logic_vector(2 downto 0) := (others => '0'); + port_a : out std_logic_vector(7 downto 0) := (others => '0'); + port_b : out std_logic_vector(7 downto 0) := (others => '0'); + + -- UART physical pins + uart_tx : out std_logic; + uart_rx : in std_logic + ); +end entity PIC; + +architecture rtl of PIC is + signal W : std_logic_vector(7 downto 0) := (others => '0'); + + signal alu_operation : alu_op; + signal alu_result : std_logic_vector(7 downto 0); + signal alu_skip : std_logic; + + signal mem_q : std_logic_vector(7 downto 0); + signal mem_qstatus : std_logic_vector(2 downto 0); + signal mem_we : std_logic; + signal mem_re : std_logic; + + signal bit_select : std_logic_vector(2 downto 0); + signal addr : std_logic_vector(6 downto 0); + signal sm_data : std_logic_vector(7 downto 0); + signal sm_pc : std_logic_vector(12 downto 0); + signal we_w : std_logic; + signal instr_ret : std_logic; + signal alu_status : std_logic_vector(2 downto 0); + + signal use_literal : std_logic; + signal we_status : std_logic; + signal b_operand : std_logic_vector(7 downto 0); + + signal stack_push : std_logic; + signal stack_pop : std_logic; + signal stack_din : std_logic_vector(12 downto 0); + signal stack_dout : std_logic_vector(12 downto 0); + + -- UART <-> dpram bridge signals + signal uart_tx_byte : std_logic_vector(7 downto 0); + signal uart_tx_send : std_logic; + signal uart_tx_done : std_logic; + signal uart_rx_byte : std_logic_vector(7 downto 0); + signal uart_rx_rd_en : std_logic; + signal uart_rx_empty : std_logic; + signal uart_rx_full : std_logic; + +begin + + work_reg <= W; + program_counter <= sm_pc; + instruction_return <= instr_ret; + status <= alu_status; + + b_operand_select : process(use_literal, sm_data, mem_q) + begin + if use_literal = '1' then + b_operand <= sm_data; + else + b_operand <= mem_q; + end if; + end process; + + w_reg : process(clk) + begin + if rising_edge(clk) then + if we_w = '1' then + W <= alu_result; + end if; + end if; + end process w_reg; + + sm : entity work.state_machine(rtl) + port map ( + clk => clk, + opcode => opcode, + reset => reset, + op => alu_operation, + we_mem => mem_we, + re_mem => mem_re, + we_w => we_w, + instr_ret => instr_ret, + bit_select => bit_select, + data => sm_data, + pc => sm_pc, + addr => addr, + use_literal => use_literal, + we_status => we_status, + stack_push => stack_push, + stack_pop => stack_pop, + stack_din => stack_din, + stack_dout => stack_dout, + alu_skip => alu_skip, + alu_result => alu_result + ); + + alu : entity work.alu(rtl) + port map ( + a => W, + b => b_operand, + op => alu_operation, + bit_select => bit_select, + status_in => mem_qstatus, + result => alu_result, + status => alu_status, + skip => alu_skip + ); + + stk : entity work.stack(rtl) + port map ( + clk => clk, + reset => reset, + push => stack_push, + pop => stack_pop, + din => stack_din, + dout => stack_dout + ); + + mem : entity work.dpram(rtl) + generic map (DEPTH => 128) + port map ( + clk => clk, + we => mem_we, + re => mem_re, + d => alu_result, + d_status => "00000" & alu_status, + addr => addr, + q => mem_q, + q_status => mem_qstatus, + port_a => port_a, + port_b => port_b, + we_status => we_status, + uart_tx_byte => uart_tx_byte, + uart_tx_send => uart_tx_send, + uart_tx_done => uart_tx_done, + uart_rx_byte => uart_rx_byte, + uart_rx_rd_en => uart_rx_rd_en, + uart_rx_empty => uart_rx_empty, + uart_rx_full => uart_rx_full + ); + + uart_inst : entity work.uart + generic map ( + CLK_FREQ => CLK_FREQ, + BAUD_RATE => BAUD_RATE, + CLKS_PER_BIT => CLK_FREQ / BAUD_RATE + ) + port map ( + clk => clk, + tx_should_send => uart_tx_send, + byte_in => uart_tx_byte, + tx_done => uart_tx_done, + baud_tick => open, + uart_tx => uart_tx, + uart_rx => uart_rx, + rd_en => uart_rx_rd_en, + rx_data => uart_rx_byte, + rx_empty => uart_rx_empty, + rx_full => uart_rx_full + ); + +end architecture rtl; |