Changes to the DAC-SPI interface for the get4 ADCs

diff --git a/special/spi_ltc2600.vhd b/special/spi_ltc2600.vhd
index 00f307d5b4331731be5aba76320549ef1045f64b..ede76b617b7d1011c9df6f67e47ca51b386c8eed 100644 (file)
--- a/special/spi_ltc2600.vhd
+++ b/special/spi_ltc2600.vhd
@@ -40,6 +40,7 @@ architecture spi_ltc2600_arch of spi_ltc2600 is
   signal start          : std_logic;
   signal chipselect_reg : std_logic_vector(15 downto 0) := x"0001";
   signal clear_reg      : std_logic_vector(15 downto 0) := x"0000";
+  signal invert_reg     : std_logic;
 
   signal spi_cs  : std_logic_vector(15 downto 0);
   signal spi_sck : std_logic;
@@ -70,12 +71,14 @@ begin
         BUS_ACK_OUT <= '1';
         if BUS_ADDR_IN(4) = '0' then
           ram(addr) <= BUS_DATA_IN;
-        elsif BUS_ADDR_IN(1) = '1' then
+        elsif BUS_ADDR_IN(2) = '1' then
           clear_reg <= BUS_DATA_IN(15 downto 0);
+        elsif BUS_ADDR_IN(3) = '1' then
+          invert_reg <= BUS_DATA_IN(0);
         elsif BUS_ADDR_IN(0) = '1' then
           ctrl_reg <= BUS_DATA_IN;
           start    <= '1';
-        else --if BUS_ADDR_IN(0) = '0' then
+        else                            --if BUS_ADDR_IN(0) = '0' then
           chipselect_reg <= BUS_DATA_IN(15 downto 0);
         end if;
       else
@@ -88,12 +91,15 @@ begin
         BUS_DATA_OUT <= ram(addr);
       elsif BUS_ADDR_IN(0) = '1' then
         BUS_DATA_OUT <= ctrl_reg;
-      elsif BUS_ADDR_IN(1) = '1' then
+      elsif BUS_ADDR_IN(2) = '1' then
         BUS_DATA_OUT(15 downto 0)  <= clear_reg;
         BUS_DATA_OUT(31 downto 16) <= x"0000";
+      elsif BUS_ADDR_IN(3) = '1' then
+        BUS_DATA_OUT(0)           <= invert_reg;
+        BUS_DATA_OUT(31 downto 1) <= (others => '0');
       elsif BUS_ADDR_IN(1) = '1' then
         BUS_DATA_OUT <= readback;
-      else --if BUS_ADDR_IN(1) = '0' then
+      else                              --if BUS_ADDR_IN(1) = '0' then
         BUS_DATA_OUT(15 downto 0)  <= chipselect_reg;
         BUS_DATA_OUT(31 downto 16) <= x"0000";
       end if;
@@ -208,10 +214,19 @@ begin
 
 
 
--- Outputs  
-  SPI_CS_OUT  <= spi_cs;
-  SPI_SCK_OUT <= spi_sck;
-  SPI_SDO_OUT <= spi_sd;
+-- Outputs
+  Invert : process(invert_reg)
+  begin
+    if invert_reg = '1' then
+      SPI_CS_OUT  <= not spi_cs;
+      SPI_SCK_OUT <= not spi_sck;
+      SPI_SDO_OUT <= not spi_sd;
+    else
+      SPI_CS_OUT  <= spi_cs;
+      SPI_SCK_OUT <= spi_sck;
+      SPI_SDO_OUT <= spi_sd;
+    end if;
+  end process Invert;
   SPI_CLR_OUT <= clear_reg;