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work on debugging cart issues #781
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Paul Gardner-Stephen committed Feb 17, 2024
1 parent 646b2a2 commit 19e0ae9
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Showing 2 changed files with 78 additions and 52 deletions.
66 changes: 43 additions & 23 deletions src/vhdl/expansion_port_controller.vhdl
View file
Original file line number Diff line number Diff line change
Expand Up @@ -174,12 +174,16 @@ architecture behavioural of expansion_port_controller is
signal oride_romh : std_logic := '0';
signal oride_roml: std_logic := '0';

signal next_read_in_progress : std_logic := '0';
signal next_rw : std_logic := '1';
signal next_io1 : std_logic := '1';
signal next_io2 : std_logic := '1';
signal next_roml : std_logic := '1';
signal next_romh : std_logic := '1';
signal next_data_dir : std_logic := '1';
signal next_data_en : std_logic := '1';
signal next_d : unsigned(7 downto 0) := x"ff";
signal next_a : unsigned(15 downto 0) := x"ffff";
signal next_ctrl_dir : std_logic := '1';

signal cart_reset_int : std_logic := '1';
Expand Down Expand Up @@ -236,7 +240,7 @@ begin
-- Set data lines to input
next_data_en <= '0'; -- negative sense on these lines: low = enable
cart_addr_en <= '0'; -- negative sense on these lines: low = enable
cart_a <= (others => 'Z');
next_a <= (others => 'Z');

-- Pull /RESET low on cartridge port, so that it can be the source of
-- GND for the joysticks. Without this, the joysticks will effectively
Expand Down Expand Up @@ -280,6 +284,7 @@ begin
end if;
next_d <= (others => 'Z');
next_data_dir <= '1';
report "Setting next_data_dir to output (joystick cart mode)";
cart_laddr_dir <= '1';
next_d(7 downto 0) <= (others => '1');
cart_a(7 downto 0) <= (others => '1');
Expand All @@ -288,6 +293,7 @@ begin
-- Tristate lines to allow time for them to be pulled low again if
-- required
next_data_dir <= '0';
report "Setting next_data_dir to input (joystick cart mode)";
next_d <= (others => 'Z');
cart_laddr_dir <= '0';
cart_a(7 downto 0) <= (others => 'Z');
Expand Down Expand Up @@ -319,6 +325,8 @@ begin
-- Tick dot clock
report "dotclock tick";



-- Ensure /RW, /IO1, /IO2 and DATA lines are held for
-- long enough after rising clock edge.
-- In theory, 60ns should be long enough, but I'm not
Expand All @@ -328,11 +336,18 @@ begin
-- So instead we delay for 1 complete clock at 8MHz
-- = 125ns, which is less than the 6502's maximum rated
-- 150ns.
if cart_dotclock_internal='1' and phi2_ticker = 1 then
report "Propagating next cycle values to expansion port lines (RW=" & std_logic'image(next_rw) & ")";
if phi2_ticker = 1 then
report "PORT: Propagating next cycle values to expansion port lines (RW=" & std_logic'image(next_rw)
& ", addr=$" & to_hexstring(next_a)
& ", io1=" & std_logic'image(next_io1)
& ", io2=" & std_logic'image(next_io2)
& ", roml=" & std_logic'image(next_roml)
& ", romh=" & std_logic'image(next_romh)
& ")";
cart_rw <= next_rw;
cart_io1 <= next_io1;
cart_io2 <= next_io2;
cart_a <= next_a;
if next_data_dir='1' then
cart_d <= (others => 'Z');
report "PORT: cart_d: TRi-state";
Expand All @@ -343,17 +358,17 @@ begin
cart_data_dir <= next_data_dir;
cart_data_en <= next_data_en;
cart_ctrl_dir <= next_ctrl_dir;
read_in_progress <= next_read_in_progress;
report "PORT: Setting read_in_progress to " & std_logic'image(next_read_in_progress);
end if;

cart_access_read_strobe <= '0';

cart_dotclock <= not cart_dotclock_internal;
cart_dotclock_internal <= not cart_dotclock_internal;
if phi2_ticker /= 0 and phi2_ticker /= 15 then
phi2_ticker <= phi2_ticker + 1;
elsif phi2_ticker = 15 then
phi2_ticker <= (others => '0');
elsif phi2_ticker = 0 then


elsif phi2_ticker = 0 then
report "phi2 tick + ~60ns hold time";
-- At this point we still have time to accept a new request and
-- schedule it immediately, as we hold the values from the previous
Expand Down Expand Up @@ -386,7 +401,7 @@ begin
cart_phi2_internal <= not cart_phi2_internal;

-- Record data from bus if we are waiting on it
if read_in_progress='1' then
if read_in_progress='1' and cart_phi2_internal='0' then
-- XXX Debug: show stats on probing cartridge flags
case cart_access_address(15 downto 0) is
when x"0000" =>
Expand Down Expand Up @@ -464,10 +479,11 @@ begin
fake_reset_sequence_phase <= fake_reset_sequence_phase + 1;

cart_busy <= '1';
cart_a <= cart_access_address(15 downto 0);
next_a <= cart_access_address(15 downto 0);
next_ctrl_dir <= '1'; -- make R/W, /IO1, /IO2 etc output
report "Setting cart_a, selecting read, setting next_data_dir to input";
next_rw <= '1';
next_data_dir <= not '1';
next_data_dir <= '0'; -- Set data lines to input
next_data_en <= '0'; -- negative sense on these lines: low = enable
cart_addr_en <= '0'; -- negative sense on these lines: low = enable

Expand Down Expand Up @@ -524,7 +540,8 @@ begin
if (not_joystick_cartridge = '1' and force_joystick_cartridge='0') or (disable_joystick_cartridge='1') then

cart_ctrl_dir <= '1'; -- make R/W, /IO1, /IO2 etc output
cart_a <= cart_access_address(15 downto 0);
next_a <= cart_access_address(15 downto 0);
report "Setting next_data_dir to " & std_logic'image(not cart_access_read) & " from cart_access_read";
next_data_dir <= not cart_access_read;
next_data_en <= cart_access_read; -- negative sense on these lines: low = enable
cart_addr_en <= '0'; -- negative sense on these lines: low = enable
Expand All @@ -545,49 +562,52 @@ begin
-- requested).
if (cart_access_address(15 downto 12) = x"8")
or (cart_access_address(15 downto 12) = x"9") then
cart_roml <= '0';
next_roml <= '0';
else
cart_roml <= '1';
next_roml <= '1';
end if;
if (cart_access_address(15 downto 12) = x"A")
or (cart_access_address(15 downto 12) = x"B")
or (cart_access_address(15 downto 12) = x"E")
or (cart_access_address(15 downto 12) = x"F") then
cart_romh <= '0';
next_romh <= '0';
else
cart_romh <= '1';
next_romh <= '1';
end if;
end if;

if cart_access_read='1' then
read_in_progress <= '1';
if (not_joystick_cartridge = '1' and force_joystick_cartridge='0') or (disable_joystick_cartridge='1') then
-- Tri-state with pull-up
report "Tristating cartridge port data lines.";
report "Tristating cartridge port data lines, setting next_data_dir to input.";
next_d <= (others => 'Z');
next_data_en <= '1';
next_data_dir <= '0'; -- set data lines to input
next_read_in_progress <= '1';
end if;
else
read_in_progress <= '0';
next_read_in_progress <= '0';
if (not_joystick_cartridge = '1' and force_joystick_cartridge='0') or (disable_joystick_cartridge='1') then
next_d <= cart_access_wdata;
report "setting next_data_dir to output";
next_data_dir <= '1'; -- set data lines to output
next_rw <= '0';
report "Write data is $" & to_hexstring(cart_access_wdata);
end if;
end if;
else
if (not_joystick_cartridge = '1' and force_joystick_cartridge='0') or (disable_joystick_cartridge='1') then
cart_access_accept_strobe <= '0';
cart_a <= (others => 'Z');
cart_roml <= '1';
cart_romh <= '1';
next_a <= (others => 'Z');
next_roml <= '1';
next_romh <= '1';
next_io1 <= '1';
next_io2 <= '1';
next_rw <= '1';
next_ctrl_dir <= '1'; -- make R/W, /IO1, /IO2 etc output
report "Tristating cart_a, selecting read";
end if;
read_in_progress <= '0';
next_read_in_progress <= '0';
cart_busy <= '0';
end if;
else
Expand Down
64 changes: 35 additions & 29 deletions src/vhdl/tb_cartridges.vhdl
View file
Original file line number Diff line number Diff line change
Expand Up @@ -192,39 +192,45 @@ begin
procedure model_64k_cart is
begin
cm_last_phi2 <= cart_phi2;

-- Cartridge reading is asynchronous
if cart_rw='1' then
if cart_roml='0' then
report "CART64K: PHI2 rising edge: ROML READ $" & to_hexstring(cart_a);
-- Correctly model when we are cross-driving cart_d lines
if cart_data_dir='1' then
report "CART64K: cart_data_dir set to output when cart was asked to present cart_d lines: CROSS DRIVING";
cart_d_in <= (others => 'X');
else
cart_d_in <= to_unsigned(to_integer(cart_a(7 downto 0)) + cart_bank,8);
cart_driving <= '1';
end if;
report "CART: cart_d_in: set to " & to_01UXstring(cart_a(7 downto 0));
elsif cart_io1='0' then
report "CART64K: PHI2 rising edgle: IO1 READ $" & to_hexstring(cart_a);
-- Correctly model when we are cross-driving cart_d lines
if cart_data_dir='1' then
report "CART64K: cart_data_dir set to output when cart was asked to present cart_d lines: CROSS DRIVING";
cart_d_in <= (others => 'X');
else
cart_d_in <= to_unsigned(to_integer(cart_a(7 downto 0)) + cart_bank,8);
cart_driving <= '1';
end if;
report "CART: cart_d_in: set to " & to_01UXstring(cart_a(7 downto 0));
else
cart_d_in <= (others => 'Z');
if cart_driving = '1' then
report "CART: cart_d: Tri-state";
cart_driving <= '0';
end if;
end if;
end if;

if cm_last_phi2='0' and cart_phi2='1' then
report "CART64K: Cart status A=$" & to_hexstring(cart_a) & ", D=$" & to_hexstring(cart_d) & ", R/_W = " & std_logic'image(cart_rw);

cart_driving <= '0';
host_driving <= cart_data_dir;
if cart_rw='1' then
if cart_roml='0' then
report "CART64K: PHI2 rising edge: ROML READ $" & to_hexstring(cart_a);
-- Correctly model when we are cross-driving cart_d lines
if cart_data_dir='1' then
report "CART64K: cart_data_dir set to output when cart was asked to present cart_d lines: CROSS DRIVING";
cart_d_in <= (others => 'X');
else
cart_d_in <= to_unsigned(to_integer(cart_a(7 downto 0)) + cart_bank,8);
cart_driving <= '1';
end if;
report "CART: cart_d_in: set to " & to_01UXstring(cart_a(7 downto 0));
elsif cart_io1='0' then
report "CART64K: PHI2 rising edgle: IO1 READ $" & to_hexstring(cart_a);
-- Correctly model when we are cross-driving cart_d lines
if cart_data_dir='1' then
report "CART64K: cart_data_dir set to output when cart was asked to present cart_d lines: CROSS DRIVING";
cart_d_in <= (others => 'X');
else
cart_d_in <= to_unsigned(to_integer(cart_a(7 downto 0)) + cart_bank,8);
cart_driving <= '1';
end if;
report "CART: cart_d_in: set to " & to_01UXstring(cart_a(7 downto 0));
else
cart_d_in <= (others => 'Z');
report "CART: cart_d: Tri-state";
end if;
else
if cart_rw='0' then
report "CART64K: PHI2 rising edge: WRITE $" & to_hexstring(cart_a) & " <- $" & to_hexstring(cart_d);
cart_d_in <= (others => 'Z');
if cart_io1='0' and cart_a(7 downto 0) = x"00" then
Expand Down

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