diff options
Diffstat (limited to 'zpu/hdl/zpu4/src/zpuio_bram.vhd')
| -rw-r--r-- | zpu/hdl/zpu4/src/zpuio_bram.vhd | 229 |
1 files changed, 229 insertions, 0 deletions
diff --git a/zpu/hdl/zpu4/src/zpuio_bram.vhd b/zpu/hdl/zpu4/src/zpuio_bram.vhd new file mode 100644 index 0000000..5d3f409 --- /dev/null +++ b/zpu/hdl/zpu4/src/zpuio_bram.vhd @@ -0,0 +1,229 @@ +library IEEE;
+use IEEE.STD_LOGIC_1164.ALL;
+use IEEE.STD_LOGIC_UNSIGNED.ALL;
+
+library work;
+use work.zpu_config.all;
+use work.zpupkg.all;
+
+entity zpuio is
+ port ( areset : in std_logic;
+ cpu_clk : in std_logic;
+ clk_status : in std_logic_vector(2 downto 0);
+ cpu_din : in std_logic_vector(15 downto 0);
+ cpu_a : in std_logic_vector(20 downto 0);
+ cpu_we : in std_logic_vector(1 downto 0);
+ cpu_re : in std_logic;
+ cpu_dout : inout std_logic_vector(15 downto 0));
+end zpuio;
+
+architecture behave of zpuio is
+
+signal timer_read : std_logic_vector(7 downto 0);
+--signal timer_write : std_logic_vector(7 downto 0);
+signal timer_we : std_logic;
+
+
+signal io_busy : std_logic;
+signal io_read : std_logic_vector(7 downto 0);
+--signal io_write : std_logic_vector(7 downto 0);
+signal io_addr : std_logic_vector(maxAddrBit downto minAddrBit);
+signal io_writeEnable : std_logic;
+signal Enable : std_logic;
+
+signal din : std_logic_vector(7 downto 0);
+signal dout : std_logic_vector(7 downto 0);
+signal adr : std_logic_vector(15 downto 0);
+signal break : std_logic;
+signal we : std_logic;
+signal re : std_logic;
+
+
+-- uart forwarding...
+
+signal uartTXPending : std_logic;
+signal uartTXCleared : std_logic;
+signal uartData : std_logic_vector(7 downto 0);
+
+signal readingTimer : std_logic;
+
+
+
+
+signal mem_busy : std_logic;
+signal mem_read : std_logic_vector(wordSize-1 downto 0);
+signal mem_write : std_logic_vector(wordSize-1 downto 0);
+signal mem_addr : std_logic_vector(maxAddrBitIncIO downto 0);
+signal mem_writeEnable : std_logic;
+signal mem_readEnable : std_logic;
+signal mem_writeMask: std_logic_vector(wordBytes-1 downto 0);
+
+
+
+
+--signal io_mem_read : std_logic_vector(7 downto 0);
+--signal io_mem_writeEnable : std_logic;
+--signal io_mem_readEnable : std_logic;
+signal io_readEnable : std_logic;
+
+
+
+
+
+begin
+
+ io_addr <= mem_addr(maxAddrBit downto minAddrBit);
+
+ timerinst: timer port map (
+ clk => cpu_clk,
+ areset => areset,
+ we => timer_we,
+ din => mem_write(7 downto 0),
+ adr => io_addr(4 downto 2),
+ dout => timer_read);
+
+ zpu: zpu_core port map (
+ clk => cpu_clk ,
+ areset => areset,
+ in_mem_busy => mem_busy,
+ mem_read => mem_read,
+ mem_write => mem_write,
+ out_mem_addr => mem_addr,
+ out_mem_writeEnable => mem_writeEnable,
+ out_mem_readEnable => mem_readEnable,
+ mem_writeMask => mem_writeMask,
+ interrupt => '0',
+ break => break);
+
+
+
+
+ -- Read/write are on different addresses
+ -- The registers are 8 bits and mapped to bit[7:0]
+ --
+ -- 0xC000 Write: Writes to UART TX FIFO (4 byte FIFO)
+ -- Read : Reads from UART RX FIFO (4 byte FIFO)
+ -- 0xC004 Read : UART status register
+ -- Bit 0 = RX FIFO empty
+ -- Bit 1 = TX FIFO full
+ -- 0xA000 Skrive: LED's (8 stk.)
+
+ -- 0x9000 Write: bit 0: 1= reset counter
+ -- 0= counter running
+ -- bit 1: 1= sample counter (when set to 1)
+ -- 0=not used
+ -- Read : counter bit[7:0]
+ -- 0x9004 Read: counter bit [15:8]
+ -- 0x9008 Read: counter bit [23:16]
+ -- 0x900C Read: counter bit [31:24]
+ -- 0x9010 Read: counter bit [39:32]
+ -- 0x9014 Read: counter bit [47:40]
+ -- 0x9018 Read: counter bit [55:48]
+ -- 0x901C Read: counter bit [63:56]
+ --
+ -- 0x8800 Read: unsigned 8-bit integer with FPGA frequency (in MHz)
+
+ fauxUart:
+ process(cpu_clk, areset)
+ begin
+ if areset = '1' then
+ io_busy <= '0';
+ uartTXPending <= '0';
+ timer_we <= '0';
+ io_busy <= '0';
+ uartData <= x"58"; -- 'X'
+ readingTimer <= '0';
+ elsif (cpu_clk'event and cpu_clk = '1') then
+ timer_we <= '0';
+ io_busy <= '0';
+ if uartTXCleared = '1' then
+ uartTXPending <= '0';
+ end if;
+
+ if io_writeEnable = '1' then
+ if io_addr=x"1000" then
+ -- Write to UART
+ uartData <= mem_write(7 downto 0);
+ uartTXPending <= '1';
+ io_busy <= '1';
+ elsif io_addr(12)='1' then
+ timer_we <= '1';
+ io_busy <= '1';
+ else
+ report "Illegal IO write" severity failure;
+ end if;
+ end if;
+ if (io_readEnable = '1') then
+ if io_addr=x"1001" then
+ io_read <= (0=>'1', -- recieve empty
+ 1 => uartTXPending, -- tx full
+ others => '0');
+ io_busy <= '1';
+ elsif io_addr(12)='1' then
+ readingTimer <= '1';
+ io_busy <= '1';
+ elsif io_addr(11)='1' then
+ io_read <= ZPU_Frequency;
+ io_busy <= '1';
+ else
+ report "Illegal IO read" severity failure;
+ end if;
+
+ else
+ if (readingTimer = '1') then
+ readingTimer <= '0';
+ io_read <= timer_read;
+ io_busy <= '0';
+ else
+ io_read <= (others => '1');
+ end if;
+ end if;
+ end if;
+ end process;
+
+
+ forwardUARTOutputToARM:
+ process(cpu_clk, areset)
+ begin
+ if areset = '1' then
+ uartTXCleared <= '0';
+ elsif (cpu_clk = '1' and cpu_clk'event) then
+ if cpu_we(0) = '1' and cpu_a(3 downto 1) = "000" then
+ uartTXCleared <= cpu_din(0);
+ else
+ uartTXCleared <= uartTXCleared;
+ end if;
+ end if;
+ end process;
+
+ cpu_dout(7 downto 0) <= uartData when (cpu_re = '1' and cpu_a(3 downto 1) = "001") else (others => 'Z');
+ cpu_dout <= (0 => uartTXPending, others => '0') when (cpu_re = '1' and cpu_a(3 downto 1) = "000") else (others => 'Z');
+
+ io_writeEnable <= mem_writeEnable and mem_addr(ioBit);
+-- io_readEnable <= mem_readEnable and mem_addr(ioBit);
+ mem_busy <= io_busy or io_readEnable;
+
+ -- Memory reads either come from IO or DRAM. We need to pick the right one.
+ memorycontrol:
+ process(cpu_clk, areset)
+ begin
+ if areset = '1' then
+ io_readEnable <= '0';
+
+
+ elsif (cpu_clk'event and cpu_clk = '1') then
+ mem_read <= (others => '0');
+
+ if mem_addr(ioBit)='1' and mem_readEnable='1' then
+ io_readEnable <= '1';
+ end if;
+ if io_readEnable='1' and io_busy='0' then
+ io_readEnable <= '0';
+ mem_read(7 downto 0) <= io_read;
+ end if;
+
+ end if;
+ end process;
+
+
+end behave;
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