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Code Issues Releases Wiki Activity

[C64] UART_RX synchronizer

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Try to make UART_RX glitch-free
This commit is contained in:
Gyorgy Szombathelyi
2019-04-28 13:43:50 +02:00
parent 1796124af1
commit 122374cd31
2 changed files with 17 additions and 4 deletions
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1
cores/c64/C64_mist.qsf
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@@ -407,4 +407,5 @@ set_global_assignment -name QIP_FILE rtl/mist/rom_reconfig_pal.qip
set_global_assignment -name QIP_FILE rtl/mist/rom_reconfig_ntsc.qip
set_global_assignment -name SIGNALTAP_FILE output_files/pll.stp
set_global_assignment -name SIGNALTAP_FILE output_files/ioctl.stp
set_instance_assignment -name FAST_INPUT_REGISTER ON -to UART_RX
set_instance_assignment -name PARTITION_HIERARCHY root_partition -to | -section_id Top

20
cores/c64/rtl/mist/c64_mist.vhd
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@@ -548,6 +548,9 @@ end component cartridge;
signal erase_to : std_logic_vector(4 downto 0) := (others => '0');
signal mem_ce : std_logic;
signal uart_rxD : std_logic;
signal uart_rxD2 : std_logic;
-- sdram layout
constant C64_MEM_START : std_logic_vector(24 downto 0) := '0' & X"000000"; -- normal C64 RAM
constant CRT_MEM_START : std_logic_vector(24 downto 0) := '0' & X"100000"; -- cartdriges
@@ -839,6 +842,15 @@ begin
end if;
end process;
-- UART_RX synchronizer
process(clk_c64)
begin
if rising_edge(clk_c64) then
uart_rxD <= UART_RX;
uart_rxD2 <= uart_rxD;
end if;
end process;
ntsc_init_mode <= st_ntsc;
pll_rom_pal : entity work.rom_reconfig_pal
@@ -1124,7 +1136,7 @@ begin
end process;
-- connect user port
process (pa2_out, pb_out, joyC_c64, joyD_c64, UART_RX, st_user_port_uart)
process (pa2_out, pb_out, joyC_c64, joyD_c64, uart_rxD2, st_user_port_uart)
begin
pa2_in <= pa2_out;
if st_user_port_uart = '0' then
@@ -1142,8 +1154,8 @@ begin
else
-- UART
pb_in(7 downto 1) <= pb_out(7 downto 1);
flag2_n <= UART_RX;
pb_in(0) <= UART_RX;
flag2_n <= uart_rxD2;
pb_in(0) <= uart_rxD2;
UART_TX <= pa2_out;
end if;
end process;
@@ -1280,7 +1292,7 @@ begin
cass_motor => cass_motor,
cass_sense => cass_sense,
osd_play_stop_toggle => st_tap_play_btn or tap_playstop_key,
ear_input => UART_RX and not st_user_port_uart
ear_input => uart_rxD2 and not st_user_port_uart
);
comp_sync : entity work.composite_sync