基于FPGA的PS/2鼠標接口設計方法及其應用
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when m2_hold_clk_l =>
ps2_clk_hi_z = '0'; -- 啟動看門狗!
if (watchdog_timer_done='1') then
m2_next_state = m2_data_low_1;
else
m2_next_state = m2_hold_clk_l;
end if;
when m2_data_low_1 =>
ps2_data_hi_z = '0'; -- 數據位 開始位, d[0] and d[1]
if (fall='1' and (bitcount = 2)) then
m2_next_state = m2_data_high_1;
else
m2_next_state = m2_data_low_1;
end if;
when m2_data_high_1 =>
ps2_data_hi_z = '1'; -- 數據位 d[2]
if (fall='1' and (bitcount = 3)) then
m2_next_state = m2_data_low_2;
else
m2_next_state = m2_data_high_1;
end if;
when m2_data_low_2 =>
ps2_data_hi_z = '0'; -- 數據位 d[3]
if (fall='1' and (bitcount = 4)) then
m2_next_state = m2_data_high_2;
else
m2_next_state = m2_data_low_2;
end if;
when m2_data_high_2 =>
ps2_data_hi_z = '1'; -- 數據位 d[4],d[5],d[6],d[7]
if (fall='1' and (bitcount = 8)) then
m2_next_state = m2_data_low_3;
else
m2_next_state = m2_data_high_2;
end if;
when m2_data_low_3 =>
ps2_data_hi_z = '0'; -- 奇偶校驗位
if (fall='1') then
m2_next_state = m2_data_high_3;
else
m2_next_state = m2_data_low_3;
end if;
when m2_data_high_3 =>
ps2_data_hi_z = '1'; -- 允許鼠標拉成低電平(ACK脈沖)
if (fall='1' and (ps2_data='1')) then
m2_next_state = m2_error_no_ack;
elsif (fall='1' and (ps2_data='0')) then
m2_next_state = m2_await_response;
else
m2_next_state = m2_data_high_3;
end if;
when m2_error_no_ack =>
error_no_ack = '1';
m2_next_state = m2_error_no_ack;
-- 為了鼠標正確進入"streaming"模式，狀態極必須等待足夠長的時間，確保鼠標正確應答0xFA。
when m2_await_response =>
--if (bitcount = 22) then
m2_next_state = m2_verify;
--else
-- m2_next_state = m2_await_response;
--end if;
when others => m2_next_state = m2_wait;
end case;
end process;-----------------------------m2 狀態結束
-- 位計數器 （略）
-- 數據移位寄存器（略）
-- 看門狗時間計數器（略）
watchdog_timer_done = '1' when (watchdog_timer_count=WATCHDOG-1) else '0';
packet_good = '1'; -- 接收數據包有效標志
outdata: process (reset, clk) -- 輸出數據
begin
if (reset='0') then
left_button = '0';
right_button = '0';
elsif (clk'event and clk='1') then
if (output_strobe='1') then
left_button = q(1);
right_button = q(2);
mouseyy = not (q(6) q(6) q(30 downto 23)) + "1";
end if;
end if;
end process;
cordinatex: process (reset, clk)
begin
if (reset='0') then
mousex = "0110010000"; -- 400
elsif (clk'event and clk='1') then
if (output_strobe='1') then
if ((mousex >= 797 and q(5)='0') or (mousex = 2 and
q(5)='1')) then
mousex = mousex;
else
mousex = mousex + (q(5) q(5) q(19 downto
12));--q(5):xsign q(6):ysign
end if;
end if;
end if;
end process;
cordinatey: process (reset, clk)
begin
if (reset='0') then
mousey = "0100101100"; -- 300
elsif (clk'event and clk='1') then
if (output_strobe='1') then
if ((mousey >= 597 and q(6)='1') or (mousey = 2
and q(6)='0')) then
mousey = mousey;
else
m ousey = mousey + mouseyy; --(q(6) q(6) q(30
downto 23));
end if;
end if;
end if;
end process;
data_ready = output_strobe;
end Behavioral;
結束語
該設計采用了清華大學THCII-1創新SoPC實驗套件進行綜合、仿真和下載，測試得到了滿意的效果，完整地實現了對PS/2和VGA的時序驅動。
該設計可以被應用到各種需要鼠標操作、以VGA作為顯示的嵌入式系統中，從而大大提高人機交互能力，降低了開發成本，提高了開發效率，使系統的穩定性也得到了可靠的保障。
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