source: PlatformSupport/CustomPeripherals/pcores/w3_ad_controller_v3_01_a/hdl/verilog/user_logic.v

//----------------------------------------------------------------------------
// user_logic.v
//----------------------------------------------------------------------------
//
// ***************************************************************************
// ** Copyright (c) 1995-2011 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      **
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// ** 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.                                             **
// **                                                                       **
// ***************************************************************************
//
//----------------------------------------------------------------------------
// Modifications from base template Copyright (c) 2012 Mango Communications
// Distributed under the terms of the WARP open-source license
//   http://warp.rice.edu/license
//----------------------------------------------------------------------------
// 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>"
//----------------------------------------------------------------------------

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_Reset,                   // Bus to IP reset
    Bus2IP_Addr,                    // Bus to IP address bus
    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 ------------

// -- ADD USER PARAMETERS ABOVE THIS LINE ------------

// -- DO NOT EDIT BELOW THIS LINE --------------------
// -- Bus protocol parameters, do not add to or delete
parameter C_SLV_DWIDTH                   = 32;
parameter C_NUM_REG                      = 16;
// -- 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_Reset;
input      [0 : 31]                       Bus2IP_Addr;
input      [0 : C_SLV_DWIDTH-1]           Bus2IP_Data;
input      [0 : C_SLV_DWIDTH/8-1]         Bus2IP_BE;
input      [0 : C_NUM_REG-1]              Bus2IP_RdCE;
input      [0 : C_NUM_REG-1]              Bus2IP_WrCE;
output     [0 : C_SLV_DWIDTH-1]           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        [0 : C_SLV_DWIDTH-1]           slv_reg0;
    reg        [0 : C_SLV_DWIDTH-1]           slv_reg1;
    reg        [0 : C_SLV_DWIDTH-1]           slv_reg2;
    reg        [0 : C_SLV_DWIDTH-1]           slv_reg3;
    reg        [0 : C_SLV_DWIDTH-1]           slv_reg4;
    reg        [0 : C_SLV_DWIDTH-1]           slv_reg5;
    reg        [0 : C_SLV_DWIDTH-1]           slv_reg6;
    reg        [0 : C_SLV_DWIDTH-1]           slv_reg7;
    reg        [0 : C_SLV_DWIDTH-1]           slv_reg8;
    reg        [0 : C_SLV_DWIDTH-1]           slv_reg9;
    reg        [0 : C_SLV_DWIDTH-1]           slv_reg10;
    reg        [0 : C_SLV_DWIDTH-1]           slv_reg11;
    reg        [0 : C_SLV_DWIDTH-1]           slv_reg12;
    reg        [0 : C_SLV_DWIDTH-1]           slv_reg13;
    reg        [0 : C_SLV_DWIDTH-1]           slv_reg14;
    reg        [0 : C_SLV_DWIDTH-1]           slv_reg15;
    wire       [0 : 15]                       slv_reg_write_sel;
    wire       [0 : 15]                       slv_reg_read_sel;
    reg        [0 : C_SLV_DWIDTH-1]           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[0:15];
    assign slv_reg_read_sel  = Bus2IP_RdCE[0:15];
        
    //Removed [1] from _ack list, so ack can be delayed following write to SPI Tx register
    assign slv_write_ack = Bus2IP_WrCE[0] || 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[14] || 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: SLAVE_REG_WRITE_PROC

            if ( Bus2IP_Reset == 1 )
                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 )
                                for ( bit_index = byte_index*8; bit_index <= byte_index*8+7; bit_index = bit_index+1 )
                                    slv_reg0[bit_index] <= Bus2IP_Data[bit_index];
                    16'b0100000000000000 :
                        for ( byte_index = 0; byte_index <= (C_SLV_DWIDTH/8)-1; byte_index = byte_index+1 )
                            if ( Bus2IP_BE[byte_index] == 1 )
                                for ( bit_index = byte_index*8; bit_index <= byte_index*8+7; bit_index = bit_index+1 )
                                    slv_reg1[bit_index] <= Bus2IP_Data[bit_index];
                    16'b0010000000000000 :
                        for ( byte_index = 0; byte_index <= (C_SLV_DWIDTH/8)-1; byte_index = byte_index+1 )
                            if ( Bus2IP_BE[byte_index] == 1 )
                                for ( bit_index = byte_index*8; bit_index <= byte_index*8+7; bit_index = bit_index+1 )
                                    slv_reg2[bit_index] <= Bus2IP_Data[bit_index];
                    16'b0001000000000000 :
                        for ( byte_index = 0; byte_index <= (C_SLV_DWIDTH/8)-1; byte_index = byte_index+1 )
                            if ( Bus2IP_BE[byte_index] == 1 )
                                for ( bit_index = byte_index*8; bit_index <= byte_index*8+7; bit_index = bit_index+1 )
                                    slv_reg3[bit_index] <= Bus2IP_Data[bit_index];
                    16'b0000100000000000 :
                        for ( byte_index = 0; byte_index <= (C_SLV_DWIDTH/8)-1; byte_index = byte_index+1 )
                            if ( Bus2IP_BE[byte_index] == 1 )
                                for ( bit_index = byte_index*8; bit_index <= byte_index*8+7; bit_index = bit_index+1 )
                                    slv_reg4[bit_index] <= Bus2IP_Data[bit_index];
                    16'b0000010000000000 :
                        for ( byte_index = 0; byte_index <= (C_SLV_DWIDTH/8)-1; byte_index = byte_index+1 )
                            if ( Bus2IP_BE[byte_index] == 1 )
                                for ( bit_index = byte_index*8; bit_index <= byte_index*8+7; bit_index = bit_index+1 )
                                    slv_reg5[bit_index] <= Bus2IP_Data[bit_index];
                    16'b0000001000000000 :
                        for ( byte_index = 0; byte_index <= (C_SLV_DWIDTH/8)-1; byte_index = byte_index+1 )
                            if ( Bus2IP_BE[byte_index] == 1 )
                                for ( bit_index = byte_index*8; bit_index <= byte_index*8+7; bit_index = bit_index+1 )
                                    slv_reg6[bit_index] <= Bus2IP_Data[bit_index];
                    16'b0000000100000000 :
                        for ( byte_index = 0; byte_index <= (C_SLV_DWIDTH/8)-1; byte_index = byte_index+1 )
                            if ( Bus2IP_BE[byte_index] == 1 )
                                for ( bit_index = byte_index*8; bit_index <= byte_index*8+7; bit_index = bit_index+1 )
                                    slv_reg7[bit_index] <= Bus2IP_Data[bit_index];
                    16'b0000000010000000 :
                        for ( byte_index = 0; byte_index <= (C_SLV_DWIDTH/8)-1; byte_index = byte_index+1 )
                            if ( Bus2IP_BE[byte_index] == 1 )
                                for ( bit_index = byte_index*8; bit_index <= byte_index*8+7; bit_index = bit_index+1 )
                                    slv_reg8[bit_index] <= Bus2IP_Data[bit_index];
                    16'b0000000001000000 :
                        for ( byte_index = 0; byte_index <= (C_SLV_DWIDTH/8)-1; byte_index = byte_index+1 )
                            if ( Bus2IP_BE[byte_index] == 1 )
                                for ( bit_index = byte_index*8; bit_index <= byte_index*8+7; bit_index = bit_index+1 )
                                    slv_reg9[bit_index] <= Bus2IP_Data[bit_index];
                    16'b0000000000100000 :
                        for ( byte_index = 0; byte_index <= (C_SLV_DWIDTH/8)-1; byte_index = byte_index+1 )
                            if ( Bus2IP_BE[byte_index] == 1 )
                                for ( bit_index = byte_index*8; bit_index <= byte_index*8+7; bit_index = bit_index+1 )
                                    slv_reg10[bit_index] <= Bus2IP_Data[bit_index];
                    16'b0000000000010000 :
                        for ( byte_index = 0; byte_index <= (C_SLV_DWIDTH/8)-1; byte_index = byte_index+1 )
                            if ( Bus2IP_BE[byte_index] == 1 )
                                for ( bit_index = byte_index*8; bit_index <= byte_index*8+7; bit_index = bit_index+1 )
                                    slv_reg11[bit_index] <= Bus2IP_Data[bit_index];
                    16'b0000000000001000 :
                        for ( byte_index = 0; byte_index <= (C_SLV_DWIDTH/8)-1; byte_index = byte_index+1 )
                            if ( Bus2IP_BE[byte_index] == 1 )
                                for ( bit_index = byte_index*8; bit_index <= byte_index*8+7; bit_index = bit_index+1 )
                                    slv_reg12[bit_index] <= Bus2IP_Data[bit_index];
                    16'b0000000000000100 :
                        for ( byte_index = 0; byte_index <= (C_SLV_DWIDTH/8)-1; byte_index = byte_index+1 )
                            if ( Bus2IP_BE[byte_index] == 1 )
                                for ( bit_index = byte_index*8; bit_index <= byte_index*8+7; bit_index = bit_index+1 )
                                    slv_reg13[bit_index] <= Bus2IP_Data[bit_index];
                    16'b0000000000000010 :
                        for ( byte_index = 0; byte_index <= (C_SLV_DWIDTH/8)-1; byte_index = byte_index+1 )
                            if ( Bus2IP_BE[byte_index] == 1 )
                                for ( bit_index = byte_index*8; bit_index <= byte_index*8+7; bit_index = bit_index+1 )
                                    slv_reg14[bit_index] <= Bus2IP_Data[bit_index];
                    16'b0000000000000001 :
                        for ( byte_index = 0; byte_index <= (C_SLV_DWIDTH/8)-1; byte_index = byte_index+1 )
                            if ( Bus2IP_BE[byte_index] == 1 )
                                for ( bit_index = byte_index*8; bit_index <= byte_index*8+7; bit_index = bit_index+1 )
                                    slv_reg15[bit_index] <= Bus2IP_Data[bit_index];
                    default : ;
                endcase

        end // SLAVE_REG_WRITE_PROC

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

            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


    assign IP2Bus_Data    = slv_ip2bus_data;

    //Reads occur immediately; acknowledge in same cycle as access
    assign IP2Bus_RdAck   = slv_read_ack;
    //assign IP2Bus_WrAck   = slv_write_ack; //Overridden below
    assign IP2Bus_Error   = 0;

    /* Address map:
        HDL is coded [MSB:LSB] = [0:31]
        regX[0]  maps to 0x80000000 in C driver
        regX[31] 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}
        [29:31] Clock divider bit sel (00=0.5*busclk, 01=0.25*busclk, ...) 0x00000007
        [28   ] Reserved
        [   27] RFA_AD reset (active low) 0x00000010
        [   26] RFB_AD reset (active low) 0x00000020
        [   25] RFC_AD reset (active low) 0x00000040
        [   24] RFD_AD reset (active low) 0x00000080
        [0 :23] Reserved

    1: SPI Tx
        [24:31] Tx data byte
        [16:23] 8-bit register address (0x00 to 0xFF all valid)
        [11:15] 5'b0 (always zero)
        [ 9:10] Num bytes to Tx/Rx; must be 2'b0 for 1-byte Tx/Rx
        [    8] RW# 1=Read, 0=Write
        [    7] RFA_AD chip select mask
        [    6] RFB_AD chip select mask
        [    5] RFC_AD chip select mask
        [    4] RFD_AD chip select mask
        [ 0: 3] Reserved
    
    2: SPI Rx: {RFA_AD_rxByte, RFB_AD_rxByte, RFC_AD_rxByte, RFD_AD_rxByte}
        [24:31] SPI Rx byte for RFA_AD 0x000000FF
        [16:23] SPI Rx byte for RFB_AD 0x0000FF00
        [ 8:15] SPI Rx byte for RFC_AD 0x00FF0000
        [ 0: 7] SPI Rx byte for RFD_AD 0xFF000000
        
    3-15: Reserved
    */


//  `define AD9963_SPI_XFER_LEN 5'd16 //AD9777 testing
    `define AD9963_SPI_XFER_LEN 24 //AD9963

//  `define AD9963_SPI_FIRST_RXBIT 5'd8 //AD9777 testing (8-bit instruction, 8-bit data)
    `define AD9963_SPI_FIRST_RXBIT 5'd16 //AD9963 (16-bit instruction, 8-bit data)
    
    
    wire [0:4] 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 [0:2] clk_div_sel;
    wire spi_xfer_done;
    
    wire [0:31] RFA_AD_spi_rxData;
    wire [0:31] RFB_AD_spi_rxData;
    wire [0:31] RFC_AD_spi_rxData;
    wire [0:31] 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[24:31];
    assign RFB_AD_spi_rx_byte = RFB_AD_spi_rxData[24:31];
    assign RFC_AD_spi_rx_byte = RFC_AD_spi_rxData[24:31];
    assign RFD_AD_spi_rx_byte = RFD_AD_spi_rxData[24:31];
    
    //SPI clock divider selection
    assign clk_div_sel = slv_reg0[29:31]; //0x7 from driver

    //SPI device resets (active low)
    assign RFA_AD_reset_n = slv_reg0[27]; //0x10 from driver
    assign RFB_AD_reset_n = slv_reg0[26]; //0x20 from driver
    assign RFC_AD_reset_n = slv_reg0[25]; //0x40 from driver
    assign RFD_AD_reset_n = slv_reg0[24]; //0x80 from driver

    //SPI device chip selects (active high; inverted before use below)
    assign RFA_AD_spi_cs = slv_reg1[7]; //0x01000000 from driver
    assign RFB_AD_spi_cs = slv_reg1[6]; //0x02000000 from driver
    assign RFC_AD_spi_cs = slv_reg1[5]; //0x04000000 from driver
    assign RFD_AD_spi_cs = slv_reg1[4]; //0x08000000 from driver

    //Internal signal for read vs. write transaction
    assign spi_rnw = slv_reg1[32-`AD9963_SPI_XFER_LEN]; //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[1];

    //spi_tx_reg_write (Bus2IP_WrCE[1]) 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_Reset),
        .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