source: PlatformSupport/CustomPeripherals/pcores/w3_ad_controller_axi_v3_01_a/hdl/verilog/user_logic.v

//----------------------------------------------------------------------------
// user_logic.v - module
//----------------------------------------------------------------------------
//
// ***************************************************************************
// ** Copyright (c) 1995-2012 Xilinx, Inc.  All rights reserved.            **
// **                                                                       **
// ** Xilinx, Inc.                                                          **
// ** XILINX IS PROVIDING THIS DESIGN, CODE, OR INFORMATION "AS IS"         **
// ** AS A COURTESY TO YOU, SOLELY FOR USE IN DEVELOPING PROGRAMS AND       **
// ** SOLUTIONS FOR XILINX DEVICES.  BY PROVIDING THIS DESIGN, CODE,        **
// ** OR INFORMATION AS ONE POSSIBLE IMPLEMENTATION OF THIS FEATURE,        **
// ** APPLICATION OR STANDARD, XILINX IS MAKING NO REPRESENTATION           **
// ** THAT THIS IMPLEMENTATION IS FREE FROM ANY CLAIMS OF INFRINGEMENT,     **
// ** AND YOU ARE RESPONSIBLE FOR OBTAINING ANY RIGHTS YOU MAY REQUIRE      **
// ** FOR YOUR IMPLEMENTATION.  XILINX EXPRESSLY DISCLAIMS ANY              **
// ** WARRANTY WHATSOEVER WITH RESPECT TO THE ADEQUACY OF THE               **
// ** IMPLEMENTATION, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OR        **
// ** REPRESENTATIONS THAT THIS IMPLEMENTATION IS FREE FROM CLAIMS OF       **
// ** INFRINGEMENT, IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS       **
// ** FOR A PARTICULAR PURPOSE.                                             **
// **                                                                       **
// ***************************************************************************
//
//----------------------------------------------------------------------------
// Filename:          user_logic.v
// Version:           3.01.a
// Description:       User logic module.
// Date:              Tue Feb 26 12:57:13 2013 (by Create and Import Peripheral Wizard)
// Verilog Standard:  Verilog-2001
//----------------------------------------------------------------------------
// Naming Conventions:
//   active low signals:                    "*_n"
//   clock signals:                         "clk", "clk_div#", "clk_#x"
//   reset signals:                         "rst", "rst_n"
//   generics:                              "C_*"
//   user defined types:                    "*_TYPE"
//   state machine next state:              "*_ns"
//   state machine current state:           "*_cs"
//   combinatorial signals:                 "*_com"
//   pipelined or register delay signals:   "*_d#"
//   counter signals:                       "*cnt*"
//   clock enable signals:                  "*_ce"
//   internal version of output port:       "*_i"
//   device pins:                           "*_pin"
//   ports:                                 "- Names begin with Uppercase"
//   processes:                             "*_PROCESS"
//   component instantiations:              "<ENTITY_>I_<#|FUNC>"
//----------------------------------------------------------------------------

`uselib lib=unisims_ver
`uselib lib=proc_common_v3_00_a

module user_logic
(
  // -- ADD USER PORTS BELOW THIS LINE ---------------
    RFA_AD_spi_sclk,
    RFA_AD_spi_cs_n,
    RFA_AD_spi_sdio,
    RFA_AD_reset_n,

    RFB_AD_spi_sclk,
    RFB_AD_spi_cs_n,
    RFB_AD_spi_sdio,
    RFB_AD_reset_n,
    
    RFC_AD_spi_sclk,
    RFC_AD_spi_cs_n,
    RFC_AD_spi_sdio,
    RFC_AD_reset_n,
    
    RFD_AD_spi_sclk,
    RFD_AD_spi_cs_n,
    RFD_AD_spi_sdio,
    RFD_AD_reset_n,
  // -- ADD USER PORTS ABOVE THIS LINE ---------------

  // -- DO NOT EDIT BELOW THIS LINE ------------------
  // -- Bus protocol ports, do not add to or delete 
  Bus2IP_Clk,                     // Bus to IP clock
  Bus2IP_Resetn,                  // Bus to IP reset
  Bus2IP_Data,                    // Bus to IP data bus
  Bus2IP_BE,                      // Bus to IP byte enables
  Bus2IP_RdCE,                    // Bus to IP read chip enable
  Bus2IP_WrCE,                    // Bus to IP write chip enable
  IP2Bus_Data,                    // IP to Bus data bus
  IP2Bus_RdAck,                   // IP to Bus read transfer acknowledgement
  IP2Bus_WrAck,                   // IP to Bus write transfer acknowledgement
  IP2Bus_Error                    // IP to Bus error response
  // -- DO NOT EDIT ABOVE THIS LINE ------------------
); // user_logic

// -- ADD USER PARAMETERS BELOW THIS LINE ------------
// --USER parameters added here 
// -- ADD USER PARAMETERS ABOVE THIS LINE ------------

// -- DO NOT EDIT BELOW THIS LINE --------------------
// -- Bus protocol parameters, do not add to or delete
parameter C_NUM_REG                      = 16;
parameter C_SLV_DWIDTH                   = 32;
// -- DO NOT EDIT ABOVE THIS LINE --------------------

// -- ADD USER PORTS BELOW THIS LINE -----------------
    output RFA_AD_spi_sclk;
    output RFA_AD_spi_cs_n;
    inout RFA_AD_spi_sdio;
    output RFA_AD_reset_n;

    output RFB_AD_spi_sclk;
    output RFB_AD_spi_cs_n;
    inout RFB_AD_spi_sdio;
    output RFB_AD_reset_n;

    output RFC_AD_spi_sclk;
    output RFC_AD_spi_cs_n;
    inout RFC_AD_spi_sdio;
    output RFC_AD_reset_n;

    output RFD_AD_spi_sclk;
    output RFD_AD_spi_cs_n;
    inout RFD_AD_spi_sdio;
    output RFD_AD_reset_n;
// -- ADD USER PORTS ABOVE THIS LINE -----------------

// -- DO NOT EDIT BELOW THIS LINE --------------------
// -- Bus protocol ports, do not add to or delete
input                                     Bus2IP_Clk;
input                                     Bus2IP_Resetn;
input      [C_SLV_DWIDTH-1 : 0]           Bus2IP_Data;
input      [C_SLV_DWIDTH/8-1 : 0]         Bus2IP_BE;
input      [C_NUM_REG-1 : 0]              Bus2IP_RdCE;
input      [C_NUM_REG-1 : 0]              Bus2IP_WrCE;
output     [C_SLV_DWIDTH-1 : 0]           IP2Bus_Data;
output                                    IP2Bus_RdAck;
output                                    IP2Bus_WrAck;
output                                    IP2Bus_Error;
// -- DO NOT EDIT ABOVE THIS LINE --------------------

//----------------------------------------------------------------------------
// Implementation
//----------------------------------------------------------------------------

  // --USER nets declarations added here, as needed for user logic

  // Nets for user logic slave model s/w accessible register example
  reg        [C_SLV_DWIDTH-1 : 0]           slv_reg0;
  reg        [C_SLV_DWIDTH-1 : 0]           slv_reg1;
  reg        [C_SLV_DWIDTH-1 : 0]           slv_reg2;
  reg        [C_SLV_DWIDTH-1 : 0]           slv_reg3;
  reg        [C_SLV_DWIDTH-1 : 0]           slv_reg4;
  reg        [C_SLV_DWIDTH-1 : 0]           slv_reg5;
  reg        [C_SLV_DWIDTH-1 : 0]           slv_reg6;
  reg        [C_SLV_DWIDTH-1 : 0]           slv_reg7;
  reg        [C_SLV_DWIDTH-1 : 0]           slv_reg8;
  reg        [C_SLV_DWIDTH-1 : 0]           slv_reg9;
  reg        [C_SLV_DWIDTH-1 : 0]           slv_reg10;
  reg        [C_SLV_DWIDTH-1 : 0]           slv_reg11;
  reg        [C_SLV_DWIDTH-1 : 0]           slv_reg12;
  reg        [C_SLV_DWIDTH-1 : 0]           slv_reg13;
  reg        [C_SLV_DWIDTH-1 : 0]           slv_reg14;
  reg        [C_SLV_DWIDTH-1 : 0]           slv_reg15;
  wire       [15 : 0]                       slv_reg_write_sel;
  wire       [15 : 0]                       slv_reg_read_sel;
  reg        [C_SLV_DWIDTH-1 : 0]           slv_ip2bus_data;
  wire                                      slv_read_ack;
  wire                                      slv_write_ack;
  integer                                   byte_index, bit_index;

  // USER logic implementation added here

  // ------------------------------------------------------
  // Example code to read/write user logic slave model s/w accessible registers
  // 
  // Note:
  // The example code presented here is to show you one way of reading/writing
  // software accessible registers implemented in the user logic slave model.
  // Each bit of the Bus2IP_WrCE/Bus2IP_RdCE signals is configured to correspond
  // to one software accessible register by the top level template. For example,
  // if you have four 32 bit software accessible registers in the user logic,
  // you are basically operating on the following memory mapped registers:
  // 
  //    Bus2IP_WrCE/Bus2IP_RdCE   Memory Mapped Register
  //                     "1000"   C_BASEADDR + 0x0
  //                     "0100"   C_BASEADDR + 0x4
  //                     "0010"   C_BASEADDR + 0x8
  //                     "0001"   C_BASEADDR + 0xC
  // 
  // ------------------------------------------------------

  assign slv_reg_write_sel = Bus2IP_WrCE[15:0];
  assign slv_reg_read_sel  = Bus2IP_RdCE[15:0];

  //Removed [14] from write_ack, so ack can be delayed following write to SPI Tx register
  // WrCE/RdCE[15:0] map to slv_reg[0:15]
  assign slv_write_ack     = Bus2IP_WrCE[0] || Bus2IP_WrCE[1] || Bus2IP_WrCE[2] || Bus2IP_WrCE[3] || Bus2IP_WrCE[4] || Bus2IP_WrCE[5] || Bus2IP_WrCE[6] || Bus2IP_WrCE[7] || Bus2IP_WrCE[8] || Bus2IP_WrCE[9] || Bus2IP_WrCE[10] || Bus2IP_WrCE[11] || Bus2IP_WrCE[12] || Bus2IP_WrCE[13] || Bus2IP_WrCE[15];
  assign slv_read_ack      = Bus2IP_RdCE[0] || Bus2IP_RdCE[1] || Bus2IP_RdCE[2] || Bus2IP_RdCE[3] || Bus2IP_RdCE[4] || Bus2IP_RdCE[5] || Bus2IP_RdCE[6] || Bus2IP_RdCE[7] || Bus2IP_RdCE[8] || Bus2IP_RdCE[9] || Bus2IP_RdCE[10] || Bus2IP_RdCE[11] || Bus2IP_RdCE[12] || Bus2IP_RdCE[13] || Bus2IP_RdCE[14] || Bus2IP_RdCE[15];

  // implement slave model register(s)
  always @( posedge Bus2IP_Clk )
    begin

      if ( Bus2IP_Resetn == 1'b0 )
        begin
          slv_reg0 <= 0;
          slv_reg1 <= 0;
          slv_reg2 <= 0;
          slv_reg3 <= 0;
          slv_reg4 <= 0;
          slv_reg5 <= 0;
          slv_reg6 <= 0;
          slv_reg7 <= 0;
          slv_reg8 <= 0;
          slv_reg9 <= 0;
          slv_reg10 <= 0;
          slv_reg11 <= 0;
          slv_reg12 <= 0;
          slv_reg13 <= 0;
          slv_reg14 <= 0;
          slv_reg15 <= 0;
        end
      else
        case ( slv_reg_write_sel )
          16'b1000000000000000 :
            for ( byte_index = 0; byte_index <= (C_SLV_DWIDTH/8)-1; byte_index = byte_index+1 )
              if ( Bus2IP_BE[byte_index] == 1 )
                slv_reg0[(byte_index*8) +: 8] <= Bus2IP_Data[(byte_index*8) +: 8];
          16'b0100000000000000 :
            for ( byte_index = 0; byte_index <= (C_SLV_DWIDTH/8)-1; byte_index = byte_index+1 )
              if ( Bus2IP_BE[byte_index] == 1 )
                slv_reg1[(byte_index*8) +: 8] <= Bus2IP_Data[(byte_index*8) +: 8];
          16'b0010000000000000 :
            for ( byte_index = 0; byte_index <= (C_SLV_DWIDTH/8)-1; byte_index = byte_index+1 )
              if ( Bus2IP_BE[byte_index] == 1 )
                slv_reg2[(byte_index*8) +: 8] <= Bus2IP_Data[(byte_index*8) +: 8];
          16'b0001000000000000 :
            for ( byte_index = 0; byte_index <= (C_SLV_DWIDTH/8)-1; byte_index = byte_index+1 )
              if ( Bus2IP_BE[byte_index] == 1 )
                slv_reg3[(byte_index*8) +: 8] <= Bus2IP_Data[(byte_index*8) +: 8];
          16'b0000100000000000 :
            for ( byte_index = 0; byte_index <= (C_SLV_DWIDTH/8)-1; byte_index = byte_index+1 )
              if ( Bus2IP_BE[byte_index] == 1 )
                slv_reg4[(byte_index*8) +: 8] <= Bus2IP_Data[(byte_index*8) +: 8];
          16'b0000010000000000 :
            for ( byte_index = 0; byte_index <= (C_SLV_DWIDTH/8)-1; byte_index = byte_index+1 )
              if ( Bus2IP_BE[byte_index] == 1 )
                slv_reg5[(byte_index*8) +: 8] <= Bus2IP_Data[(byte_index*8) +: 8];
          16'b0000001000000000 :
            for ( byte_index = 0; byte_index <= (C_SLV_DWIDTH/8)-1; byte_index = byte_index+1 )
              if ( Bus2IP_BE[byte_index] == 1 )
                slv_reg6[(byte_index*8) +: 8] <= Bus2IP_Data[(byte_index*8) +: 8];
          16'b0000000100000000 :
            for ( byte_index = 0; byte_index <= (C_SLV_DWIDTH/8)-1; byte_index = byte_index+1 )
              if ( Bus2IP_BE[byte_index] == 1 )
                slv_reg7[(byte_index*8) +: 8] <= Bus2IP_Data[(byte_index*8) +: 8];
          16'b0000000010000000 :
            for ( byte_index = 0; byte_index <= (C_SLV_DWIDTH/8)-1; byte_index = byte_index+1 )
              if ( Bus2IP_BE[byte_index] == 1 )
                slv_reg8[(byte_index*8) +: 8] <= Bus2IP_Data[(byte_index*8) +: 8];
          16'b0000000001000000 :
            for ( byte_index = 0; byte_index <= (C_SLV_DWIDTH/8)-1; byte_index = byte_index+1 )
              if ( Bus2IP_BE[byte_index] == 1 )
                slv_reg9[(byte_index*8) +: 8] <= Bus2IP_Data[(byte_index*8) +: 8];
          16'b0000000000100000 :
            for ( byte_index = 0; byte_index <= (C_SLV_DWIDTH/8)-1; byte_index = byte_index+1 )
              if ( Bus2IP_BE[byte_index] == 1 )
                slv_reg10[(byte_index*8) +: 8] <= Bus2IP_Data[(byte_index*8) +: 8];
          16'b0000000000010000 :
            for ( byte_index = 0; byte_index <= (C_SLV_DWIDTH/8)-1; byte_index = byte_index+1 )
              if ( Bus2IP_BE[byte_index] == 1 )
                slv_reg11[(byte_index*8) +: 8] <= Bus2IP_Data[(byte_index*8) +: 8];
          16'b0000000000001000 :
            for ( byte_index = 0; byte_index <= (C_SLV_DWIDTH/8)-1; byte_index = byte_index+1 )
              if ( Bus2IP_BE[byte_index] == 1 )
                slv_reg12[(byte_index*8) +: 8] <= Bus2IP_Data[(byte_index*8) +: 8];
          16'b0000000000000100 :
            for ( byte_index = 0; byte_index <= (C_SLV_DWIDTH/8)-1; byte_index = byte_index+1 )
              if ( Bus2IP_BE[byte_index] == 1 )
                slv_reg13[(byte_index*8) +: 8] <= Bus2IP_Data[(byte_index*8) +: 8];
          16'b0000000000000010 :
            for ( byte_index = 0; byte_index <= (C_SLV_DWIDTH/8)-1; byte_index = byte_index+1 )
              if ( Bus2IP_BE[byte_index] == 1 )
                slv_reg14[(byte_index*8) +: 8] <= Bus2IP_Data[(byte_index*8) +: 8];
          16'b0000000000000001 :
            for ( byte_index = 0; byte_index <= (C_SLV_DWIDTH/8)-1; byte_index = byte_index+1 )
              if ( Bus2IP_BE[byte_index] == 1 )
                slv_reg15[(byte_index*8) +: 8] <= Bus2IP_Data[(byte_index*8) +: 8];
          default : begin
            slv_reg0 <= slv_reg0;
            slv_reg1 <= slv_reg1;
            slv_reg2 <= slv_reg2;
            slv_reg3 <= slv_reg3;
            slv_reg4 <= slv_reg4;
            slv_reg5 <= slv_reg5;
            slv_reg6 <= slv_reg6;
            slv_reg7 <= slv_reg7;
            slv_reg8 <= slv_reg8;
            slv_reg9 <= slv_reg9;
            slv_reg10 <= slv_reg10;
            slv_reg11 <= slv_reg11;
            slv_reg12 <= slv_reg12;
            slv_reg13 <= slv_reg13;
            slv_reg14 <= slv_reg14;
            slv_reg15 <= slv_reg15;
                    end
        endcase

    end // SLAVE_REG_WRITE_PROC

    wire [7:0] RFA_AD_spi_rx_byte;
    wire [7:0] RFB_AD_spi_rx_byte;
    wire [7:0] RFC_AD_spi_rx_byte;
    wire [7:0] RFD_AD_spi_rx_byte;

    
  // implement slave model register read mux
  always @*//( slv_reg_read_sel or slv_reg0 or slv_reg1 or slv_reg2 or slv_reg3 or slv_reg4 or slv_reg5 or slv_reg6 or slv_reg7 or slv_reg8 or slv_reg9 or slv_reg10 or slv_reg11 or slv_reg12 or slv_reg13 or slv_reg14 or slv_reg15 )
    begin 

      case ( slv_reg_read_sel )
        16'b1000000000000000 : slv_ip2bus_data <= slv_reg0;
        16'b0100000000000000 : slv_ip2bus_data <= slv_reg1;
        16'b0010000000000000 : slv_ip2bus_data <= {RFD_AD_spi_rx_byte, RFC_AD_spi_rx_byte, RFB_AD_spi_rx_byte, RFA_AD_spi_rx_byte};
        16'b0001000000000000 : slv_ip2bus_data <= slv_reg3;
        16'b0000100000000000 : slv_ip2bus_data <= slv_reg4;
        16'b0000010000000000 : slv_ip2bus_data <= slv_reg5;
        16'b0000001000000000 : slv_ip2bus_data <= slv_reg6;
        16'b0000000100000000 : slv_ip2bus_data <= slv_reg7;
        16'b0000000010000000 : slv_ip2bus_data <= slv_reg8;
        16'b0000000001000000 : slv_ip2bus_data <= slv_reg9;
        16'b0000000000100000 : slv_ip2bus_data <= slv_reg10;
        16'b0000000000010000 : slv_ip2bus_data <= slv_reg11;
        16'b0000000000001000 : slv_ip2bus_data <= slv_reg12;
        16'b0000000000000100 : slv_ip2bus_data <= slv_reg13;
        16'b0000000000000010 : slv_ip2bus_data <= slv_reg14;
        16'b0000000000000001 : slv_ip2bus_data <= slv_reg15;
        default : slv_ip2bus_data <= 0;
      endcase

    end // SLAVE_REG_READ_PROC

  // ------------------------------------------------------------
  // Example code to drive IP to Bus signals
  // ------------------------------------------------------------

  assign IP2Bus_Data = (slv_read_ack == 1'b1) ? slv_ip2bus_data :  0 ;
//  assign IP2Bus_WrAck = slv_write_ack; //Overridden below
  assign IP2Bus_RdAck = slv_read_ack;
  assign IP2Bus_Error = 0;

    /* Address map:
        HDL is coded [MSB:LSB] = [31:0], per Xilinx's convention for AXI peripherals
        regX[31]  maps to 0x80000000 in C driver
        regX[0] maps to 0x00000001 in C driver

    0: Config: {clk_div_sel[2:0], 1'b0, RFA_AD_rst_n, RFB_AD_rst_n, RFC_AD_rst_n, RFD_AD_rst_n, 24'b0}
        [ 2: 0] Clock divider bit sel (00=0.5*busclk, 01=0.25*busclk, ...) 0x00000007
        [    3] Reserved
        [    4] RFA_AD reset (active low) 0x00000010
        [    5] RFB_AD reset (active low) 0x00000020
        [    6] RFC_AD reset (active low) 0x00000040
        [    7] RFD_AD reset (active low) 0x00000080
        [31: 8] Reserved

    1: SPI Tx
        [ 7: 0] Tx data byte 0x00FF
        [15: 8] 8-bit register address (0x00 to 0xFF all valid) 0xFF00
        [20:16] 5'b0 (always zero)
        [22:21] Num bytes to Tx/Rx; must be 2'b0 for 1-byte Tx/Rx
        [   23] RW# 1=Read, 0=Write
        [   24] RFA_AD chip select mask
        [   25] RFB_AD chip select mask
        [   26] RFC_AD chip select mask
        [   27] RFD_AD chip select mask
        [31:28] Reserved
    
    2: SPI Rx: {RFA_AD_rxByte, RFB_AD_rxByte, RFC_AD_rxByte, RFD_AD_rxByte}
        [ 7: 0] SPI Rx byte for RFA_AD 0x000000FF
        [15: 8] SPI Rx byte for RFB_AD 0x0000FF00
        [23:16] SPI Rx byte for RFC_AD 0x00FF0000
        [31:24] SPI Rx byte for RFD_AD 0xFF000000
        
    3-15: Reserved
    */
    
    `define AD9963_SPI_XFER_LEN 24 //AD9963
    `define AD9963_SPI_FIRST_RXBIT 5'd16 //AD9963 (16-bit instruction, 8-bit data)
    
    wire [4:0] spi_bitNum;
    wire spi_mosi;
    wire spi_sclk;
    wire spi_cs;
    wire spi_rnw;
    wire RFA_AD_spi_cs, RFB_AD_spi_cs, RFC_AD_spi_cs, RFD_AD_spi_cs;
    wire spi_tx_reg_write;
    wire [2:0] clk_div_sel;
    wire spi_xfer_done;
    
    wire [31:0] RFA_AD_spi_rxData;
    wire [31:0] RFB_AD_spi_rxData;
    wire [31:0] RFC_AD_spi_rxData;
    wire [31:0] RFD_AD_spi_rxData;
    
    wire RFA_AD_spi_mosi, RFA_AD_spi_miso;
    wire RFB_AD_spi_mosi, RFB_AD_spi_miso;
    wire RFC_AD_spi_mosi, RFC_AD_spi_miso;
    wire RFD_AD_spi_mosi, RFD_AD_spi_miso;
    
    //Extract bits from IPIF slave registers and control signals

    //spi_io stores 32 bits for Tx/Rx
    // AD9963 only outputs 8-bit words during reads, always the last 8 bits of the transfer
    assign RFA_AD_spi_rx_byte = RFA_AD_spi_rxData[7:0];
    assign RFB_AD_spi_rx_byte = RFB_AD_spi_rxData[7:0];
    assign RFC_AD_spi_rx_byte = RFC_AD_spi_rxData[7:0];
    assign RFD_AD_spi_rx_byte = RFD_AD_spi_rxData[7:0];
    
    //SPI clock divider selection
    assign clk_div_sel = slv_reg0[2:0]; //0x7 from driver

    //SPI device resets (active low)
    assign RFA_AD_reset_n = slv_reg0[4]; //0x10 from driver
    assign RFB_AD_reset_n = slv_reg0[5]; //0x20 from driver
    assign RFC_AD_reset_n = slv_reg0[6]; //0x40 from driver
    assign RFD_AD_reset_n = slv_reg0[7]; //0x80 from driver

    //SPI device chip selects (active high; inverted before use below)
    assign RFA_AD_spi_cs = slv_reg1[24]; //0x01000000 from driver
    assign RFB_AD_spi_cs = slv_reg1[25]; //0x02000000 from driver
    assign RFC_AD_spi_cs = slv_reg1[26]; //0x04000000 from driver
    assign RFD_AD_spi_cs = slv_reg1[27]; //0x08000000 from driver

    //Internal signal for read vs. write transaction
    assign spi_rnw = slv_reg1[`AD9963_SPI_XFER_LEN-1]; //0x00800000 from driver
    
    //Use the IPIC write-enable for the SPI Tx register as the SPI go
    // The bus will be paused until this core ACKs the write
    assign spi_tx_reg_write = Bus2IP_WrCE[14]; //WrCE[15:0] maps to slv_reg[0:15]

    //spi_tx_reg_write (Bus2IP_WrCE[14]) de-asserts as soon as transaction is ACK'd
    // so this mux switches back to the generic ACK as soon as the SPI xfer is done
    //Thus, the duration of assertion for spi_xfer_done doesn't really matter
    //A bit fast-n-loose, but works ok
    assign IP2Bus_WrAck = spi_tx_reg_write ? spi_xfer_done : slv_write_ack;

    //SPI device chip selects are active low
    assign RFA_AD_spi_cs_n = ~(RFA_AD_spi_cs & spi_cs);
    assign RFB_AD_spi_cs_n = ~(RFB_AD_spi_cs & spi_cs);
    assign RFC_AD_spi_cs_n = ~(RFC_AD_spi_cs & spi_cs);
    assign RFD_AD_spi_cs_n = ~(RFD_AD_spi_cs & spi_cs);
    
    //Mask each device's SPI clock output by its CS; no point toggling signals that will be ignored
    assign RFA_AD_spi_sclk = (spi_sclk & RFA_AD_spi_cs);
    assign RFB_AD_spi_sclk = (spi_sclk & RFB_AD_spi_cs);
    assign RFC_AD_spi_sclk = (spi_sclk & RFC_AD_spi_cs);
    assign RFD_AD_spi_sclk = (spi_sclk & RFD_AD_spi_cs);

    //All SPI devices driven by same serial data output; CS signals control who listens
    assign RFA_AD_spi_mosi = RFA_AD_spi_cs ? spi_mosi : 1'b0;
    assign RFB_AD_spi_mosi = RFB_AD_spi_cs ? spi_mosi : 1'b0;
    assign RFC_AD_spi_mosi = RFC_AD_spi_cs ? spi_mosi : 1'b0;
    assign RFD_AD_spi_mosi = RFD_AD_spi_cs ? spi_mosi : 1'b0;
    
    //AD9963 SPI data is bi-directional; IOBUFs instantiated here to switch I vs. O mid-transfer
    //Set spi_sdio pins as inputs except when actively driving, to avoid accidental drive fights
    // FPGA drives the sdio pin when:
    //   An SPI transaction is in progress AND 
    //     The transaction is a read AND the current bit is part of the instruction bytes
    //      OR
    //     The transaction is a write
    assign RFA_AD_spi_sdio_output_en = spi_cs & ( (spi_rnw & (spi_bitNum < `AD9963_SPI_FIRST_RXBIT)) | (~spi_rnw));
    assign RFB_AD_spi_sdio_output_en = spi_cs & ( (spi_rnw & (spi_bitNum < `AD9963_SPI_FIRST_RXBIT)) | (~spi_rnw));
    assign RFC_AD_spi_sdio_output_en = spi_cs & ( (spi_rnw & (spi_bitNum < `AD9963_SPI_FIRST_RXBIT)) | (~spi_rnw));
    assign RFD_AD_spi_sdio_output_en = spi_cs & ( (spi_rnw & (spi_bitNum < `AD9963_SPI_FIRST_RXBIT)) | (~spi_rnw));

    IOBUF IOBUF_RFA_AD_sdio (
        .IO(RFA_AD_spi_sdio), //Connected to actual FPGA pin
        .I(RFA_AD_spi_mosi), //Logic-> Pad, input to OBUFT
        .O(RFA_AD_spi_miso), //Pad-> Logic, output of IBUF
        .T(~RFA_AD_spi_sdio_output_en)
    );

    IOBUF IOBUF_RFB_AD_sdio (
        .IO(RFB_AD_spi_sdio), //Connected to actual FPGA pin
        .I(RFB_AD_spi_mosi), //Logic-> Pad, input to OBUFT
        .O(RFB_AD_spi_miso), //Pad-> Logic, output of IBUF
        .T(~RFB_AD_spi_sdio_output_en)
    );

    IOBUF IOBUF_RFC_AD_sdio (
        .IO(RFC_AD_spi_sdio), //Connected to actual FPGA pin
        .I(RFC_AD_spi_mosi), //Logic-> Pad, input to OBUFT
        .O(RFC_AD_spi_miso), //Pad-> Logic, output of IBUF
        .T(~RFC_AD_spi_sdio_output_en)
    );

    IOBUF IOBUF_RFD_AD_sdio (
        .IO(RFD_AD_spi_sdio), //Connected to actual FPGA pin
        .I(RFD_AD_spi_mosi), //Logic-> Pad, input to OBUFT
        .O(RFD_AD_spi_miso), //Pad-> Logic, output of IBUF
        .T(~RFD_AD_spi_sdio_output_en)
    );
    
    warp_spi_io #(.SPI_XFER_LEN(`AD9963_SPI_XFER_LEN)) spi_io
    (
        .sys_clk(Bus2IP_Clk),
        .reset(~Bus2IP_Resetn),//warp_spi_io.reset is active high
        .go(spi_tx_reg_write),
        .done(spi_xfer_done),
        .clkDiv(clk_div_sel),

        .currBitNum(spi_bitNum),

        .txData(slv_reg1),

        .rxData1(RFA_AD_spi_rxData),
        .rxData2(RFB_AD_spi_rxData),
        .rxData3(RFC_AD_spi_rxData),
        .rxData4(RFD_AD_spi_rxData),
        
        .spi_cs(spi_cs),
        .spi_sclk(spi_sclk),

        .spi_mosi(spi_mosi),
        
        .spi_miso1(RFA_AD_spi_miso),
        .spi_miso2(RFB_AD_spi_miso),
        .spi_miso3(RFC_AD_spi_miso),
        .spi_miso4(RFD_AD_spi_miso)
    );

endmodule