-
- process
- variable data_ready : std_logic;
- variable channel: channel_type;
- variable reset_re: std_logic:='0';
- variable reset_count: integer:=0;
- begin
- wait until (clk_3M1'event and clk_3M1='1');
-
- --reset rising edge detection
- adc_rst_old(0)<=adc_reset;
- adc_rst_old(1)<=adc_rst_old(0);
-
- if (adc_rst_old="01") then
- reset_re:='1';
- end if;
-
- case state is
- when reset=>
- reset_re:='0'; --clear reset flag
- adc_scs<='1'; --active-low SS
- adc_sclk<='0'; --lower clock
- data_ready:='0';
- --addresse are CH(A2,A1,A0): CH0:(0,0,1),CH1:(1,0,1),CH2:(0,1,0)
- adc_address<="001101010";
- channel:=ch0;
- adc_channels(35 downto 0)<=(others=>'1'); --for debug only - remove this line!
- adc_data(11 downto 0)<=(others=>'1');
- reset_count:=0;
- state<=rst_wait;
- when rst_wait=>
- if (reset_count<10) then
- reset_count:=reset_count+1;
- if (reset_count=7) then
- adc_scs<='0'; --give the adc some time to prepare before trensfer
- end if;
- else
- state<=f1;
- end if;
- when f1=> --1st 'fallin edge' - its not falling edge in any case-if rst clock is low before
- adc_sclk<='0'; --clk
- adc_mosi<='1'; --start bit
- state<=r1; --next state
- when r1=> --1st rising edge (adc gets the start bit, we get date..)
- adc_sclk<='1';
- adc_data(5)<=adc_miso;
- state<=f2;
- when f2=> --2nd falling edge
- adc_sclk<='0';
- adc_mosi<=adc_address(8); --A2 address
- state<=r2;
- when r2=> --2nd rising edge (adc gets A2 address)
- adc_sclk<='1';
- adc_data(4)<=adc_miso;
- state<=f3;
- when f3=> --3rd falling edge
- adc_sclk<='0';
- adc_mosi<=adc_address(7); --A1 address
- state<=r3;
- when r3=> --rising edge
- adc_sclk<='1';
- adc_data(3)<=adc_miso;
- state<=f4;
- when f4=> --4th falling edge
- adc_sclk<='0';
- adc_mosi<=adc_address(6); --A0 address
- --shift the addresses
- adc_address(8 downto 0)<=adc_address(5 downto 0) & adc_address(8 downto 6);
- state<=r4;
- when r4=> --rising edge
- adc_sclk<='1';
- adc_data(2)<=adc_miso;
- state<=f5;
- when f5=> --5th falling edge
- adc_sclk<='0';
- adc_mosi<='0'; --MODE (LOW -12bit)
- state<=r5;
- when r5=> --rising edge
- adc_sclk<='1';
- adc_data(1)<=adc_miso;
- state<=f6;
- when f6=> --6th falling edge
- adc_sclk<='0';
- adc_mosi<='1'; --SGL/DIF (HIGH - SGL=Single Ended)
- state<=r6;
- when r6=> --6th rising edge (we read last bit of conversion, adc gets SGL/DIF)
- adc_sclk<='1';
- adc_data(0)<=adc_miso;
- state<=f7;
- when f7=> -- 7th falling edge
- adc_sclk<='0';
- adc_mosi<='0'; --PD1 (power down - PD1=PD0=0 -> power down between conversion)
- state<=r7;
- when r7=> --7th rising edge, data ready
- adc_sclk<='1';
- if (data_ready='1') then
- case channel is
- when ch0=>
- adc_channels(35 downto 24)<=adc_data(11 downto 0);
- --adc_channels(35 downto 24)<=(others=>'0');
- channel:=ch1;
- when ch1=>
- adc_channels(23 downto 12)<=adc_data(11 downto 0);
- --adc_channels(23 downto 12)<=(others=>'1');
- channel:=ch2;
- when ch2=>
- adc_channels(11 downto 0)<=adc_data(11 downto 0);
- --adc_channels(11 downto 0)<=(others=>'0');
- channel:=ch0;
- end case;
- end if;
- data_ready:='1';
- state<=f8;
- when f8=> --8th falling edge
- adc_sclk<='0';
- adc_mosi<='0'; --PD0
- state<=r8;
- when r8=> --8th rising edge (adc gets PD0)
- adc_sclk<='1';
- state<=f9;
- when f9=> --9th falling edge busy state between conversion (we write nothing)
- adc_sclk<='0';
- state<=r9;
- when r9=> --9th rising edge (we nor ads get nothing)
- adc_sclk<='1';
- state<=f10;
- when f10=> --10th falling edge
- adc_sclk<='0';
- state<=r10;
- when r10=> --10th rising edge (we read 1. bit of conversion)
- adc_sclk<='1';
- adc_data(11)<=adc_miso;
- state<=f11;
- when f11=>
- adc_sclk<='0';
- state<=r11;
- when r11=> --11th rising edge
- adc_sclk<='1';
- adc_data(10)<=adc_miso;
- state<=f12;
- when f12=>
- adc_sclk<='0';
- state<=r12;
- when r12=> --12th rising edge
- adc_sclk<='1';
- adc_data(9)<=adc_miso;
- state<=f13;
- when f13=>
- adc_sclk<='0';
- state<=r13;
- when r13=> --13th rising edge
- adc_sclk<='1';
- adc_data(8)<=adc_miso;
- state<=f14;
- when f14=>
- adc_sclk<='0';
- state<=r14;
- when r14=> --14th rising edge
- adc_sclk<='1';
- adc_data(7)<=adc_miso;
- state<=f15;
- when f15=>
- adc_sclk<='0';
- --for rising edge detection in next cycle
- state<=r15;
- when r15=> --15th rising edge
- adc_sclk<='1';
- adc_data(6)<=adc_miso;
- if (reset_re='1') then --we check rising edge of reset
- state<=reset;
- else
- state<=f1;
- end if;
- end case;
- end process;