fpga: performed a forceful checkout of fpga to overwrite with current fpga code

1 files changed, 232 insertions, 159 deletions

diff --git a/fpga/usrp2/top/u2plus/u2plus.v b/fpga/usrp2/top/u2plus/u2plus.v
index e95445867..270655a8d 100644
--- a/fpga/usrp2/top/u2plus/u2plus.v
+++ b/fpga/usrp2/top/u2plus/u2plus.v
@@ -1,48 +1,96 @@
 `timescale 1ns / 1ps
+//`define DCM_FOR_RAMCLK
 //////////////////////////////////////////////////////////////////////////////////
 
 module u2plus
   (
+   input CLK_FPGA_P, input CLK_FPGA_N,  // Diff
+   
+   // ADC
+   input ADC_clkout_p, input ADC_clkout_n,
+   input ADCA_12_p, input ADCA_12_n,
+   input ADCA_10_p, input ADCA_10_n,
+   input ADCA_8_p, input ADCA_8_n,
+   input ADCA_6_p, input ADCA_6_n,
+   input ADCA_4_p, input ADCA_4_n,
+   input ADCA_2_p, input ADCA_2_n,
+   input ADCA_0_p, input ADCA_0_n,
+   input ADCB_12_p, input ADCB_12_n,
+   input ADCB_10_p, input ADCB_10_n,
+   input ADCB_8_p, input ADCB_8_n,
+   input ADCB_6_p, input ADCB_6_n,
+   input ADCB_4_p, input ADCB_4_n,
+   input ADCB_2_p, input ADCB_2_n,
+   input ADCB_0_p, input ADCB_0_n,
+   
+   // DAC
+   output reg [15:0] DACA,
+   output reg [15:0] DACB,
+   input DAC_LOCK,     // unused for now
+   
+   // DB IO Pins
+   inout [15:0] io_tx,
+   inout [15:0] io_rx,
+
    // Misc, debug
-   output [4:0] leds,  // LED4 is shared w/INIT_B
-   input [3:0] dipsw,
-   output [31:0] debug,
+   output [5:1] leds,  // LED4 is shared w/INIT_B
+   input FPGA_RESET,
    output [1:0] debug_clk,
-   output uart_tx_o,
-   input uart_rx_i,
-   
-   // Expansion
-   input exp_pps_in_p, // Diff
-   input exp_pps_in_n, // Diff
-   output exp_pps_out_p, // Diff 
-   output exp_pps_out_n, // Diff 
+   output [31:0] debug,
+   output [3:1] TXD, input [3:1] RXD, // UARTs
+   //input [3:0] dipsw,  // Forgot DIP Switches...
    
-   // GMII
-   //   GMII-CTRL
-   input GMII_COL,
-   input GMII_CRS,
+   // Clock Gen Control
+   output [1:0] clk_en,
+   output [1:0] clk_sel,
+   input CLK_FUNC,        // FIXME is an input to control the 9510
+   input CLK_STATUS,
+
+   inout SCL, inout SDA,   // I2C
+
+   // PPS
+   input PPS_IN, input PPS2_IN,
+
+   // SPI
+   output SEN_CLK, output SCLK_CLK, output MOSI_CLK, input MISO_CLK,
+   output SEN_DAC, output SCLK_DAC, output MOSI_DAC, input MISO_DAC,
+   output SEN_ADC, output SCLK_ADC, output MOSI_ADC,
+   output SEN_TX_DB, output SCLK_TX_DB, output MOSI_TX_DB, input MISO_TX_DB,
+   output SEN_TX_DAC, output SCLK_TX_DAC, output MOSI_TX_DAC,
+   output SEN_TX_ADC, output SCLK_TX_ADC, output MOSI_TX_ADC, input MISO_TX_ADC,
+   output SEN_RX_DB, output SCLK_RX_DB, output MOSI_RX_DB, input MISO_RX_DB,
+   output SEN_RX_DAC, output SCLK_RX_DAC, output MOSI_RX_DAC,
+   output SEN_RX_ADC, output SCLK_RX_ADC, output MOSI_RX_ADC, input MISO_RX_ADC,
+
+   // GigE PHY
+   input CLK_TO_MAC,
 
-   //   GMII-TX
    output reg [7:0] GMII_TXD,
    output reg GMII_TX_EN,
    output reg GMII_TX_ER,
    output GMII_GTX_CLK,
    input GMII_TX_CLK,  // 100mbps clk
 
-   //   GMII-RX
-   input [7:0] GMII_RXD,
    input GMII_RX_CLK,
+   input [7:0] GMII_RXD,
    input GMII_RX_DV,
    input GMII_RX_ER,
+   input GMII_COL,
+   input GMII_CRS,
 
-   //   GMII-Management
+   input PHY_INTn,   // open drain
    inout MDIO,
    output MDC,
-   input PHY_INTn,   // open drain
    output PHY_RESETn,
-   input PHY_CLK,   // possibly use on-board osc
-   input clk_to_mac,
-   output eth_led,
+   output ETH_LED,
+   
+//   input POR,
+   
+   // Expansion
+   input exp_time_in_p, input exp_time_in_n, // Diff
+   output exp_time_out_p, output exp_time_out_n, // Diff 
+   input exp_user_in_p, input exp_user_in_n, // Diff
+   output exp_user_out_p, output exp_user_out_n, // Diff 
    
    // SERDES
    output ser_enable,
@@ -59,75 +107,18 @@ module u2plus
    input [15:0] ser_r,
    input ser_rklsb,
    input ser_rkmsb,
-   
-   // ADC
-   input [13:0] adc_a,
-   input adc_ovf_a,
-   output adc_oen_a,
-   output adc_pdn_a,
-   
-   input [13:0] adc_b,
-   input adc_ovf_b,
-   output adc_oen_b,
-   output adc_pdn_b,
-   
-   // DAC
-   output [15:0] dac_a,
-   output [15:0] dac_b,
-   input dac_lock,     // unused for now
-   
-   // I2C
-   inout SCL,
-   inout SDA,
 
-   // Clock Gen Control
-   output [1:0] clk_en,
-   output [1:0] clk_sel,
-   input clk_func,        // FIXME is an input to control the 9510
-   input clk_status,
-
-   // Clocks
-   input clk_fpga_p,  // Diff
-   input clk_fpga_n,  // Diff
-   input pps_in,
-   input POR,
+   // SRAM
+   inout [35:0] RAM_D,
+   output [20:0] RAM_A,
+   output [3:0] RAM_BWn,
+   output RAM_ZZ,
+   output RAM_LDn,
+   output RAM_OEn,
+   output RAM_WEn,
+   output RAM_CENn,
+   output RAM_CLK,
    
-   // AD9510 SPI
-   output sclk,
-   output sen_clk,
-   output sdi,
-   input sdo,
-
-   // TX side SPI -- tx_db, tx_adc, tx_dac, 9777
-   output sen_dac,
-   output sen_tx_db,
-   output sen_tx_adc,
-   output sen_tx_dac,
-   output mosi_tx,
-   input miso_dac,
-   input miso_tx_db,
-   input miso_tx_adc,
-   output sclk_tx,
-
-   // RX side SPI
-   output sen_rx_db,
-   output sclk_rx_db,
-   input sdo_rx_db,
-   output sdi_rx_db,
-
-   output sen_rx_adc,
-   output sclk_rx_adc,
-   input sdo_rx_adc,
-   output sdi_rx_adc,
-
-   output sen_rx_dac,
-   output sclk_rx_dac,
-   output sdi_rx_dac,
-
-   // DB IO Pins
-   inout [15:0] io_tx,
-   inout [15:0] io_rx,
-
    // SPI Flash
    output flash_cs,
    output flash_clk,
@@ -135,38 +126,63 @@ module u2plus
    input flash_miso
    );
 
+   wire  CLK_TO_MAC_int, CLK_TO_MAC_int2;
+   IBUFG phyclk (.O(CLK_TO_MAC_int), .I(CLK_TO_MAC));
+   BUFG phyclk2 (.O(CLK_TO_MAC_int2), .I(CLK_TO_MAC_int));
+      
    // FPGA-specific pins connections
-   wire 	aux_clk = PHY_CLK;
-
    wire 	clk_fpga, dsp_clk, clk_div, dcm_out, wb_clk, clock_ready;
 
-   IBUFGDS clk_fpga_pin (.O(clk_fpga),.I(clk_fpga_p),.IB(clk_fpga_n));
+   IBUFGDS clk_fpga_pin (.O(clk_fpga),.I(CLK_FPGA_P),.IB(CLK_FPGA_N));
    defparam 	clk_fpga_pin.IOSTANDARD = "LVPECL_25";
    
-   wire 	exp_pps_in;
-   IBUFDS exp_pps_in_pin (.O(exp_pps_in),.I(exp_pps_in_p),.IB(exp_pps_in_n));
-   defparam 	exp_pps_in_pin.IOSTANDARD = "LVDS_25";
+   wire 	exp_time_in;
+   IBUFDS exp_time_in_pin (.O(exp_time_in),.I(exp_time_in_p),.IB(exp_time_in_n));
+   defparam 	exp_time_in_pin.IOSTANDARD = "LVDS_25";
+   
+   wire 	exp_time_out;
+   OBUFDS exp_time_out_pin (.O(exp_time_out_p),.OB(exp_time_out_n),.I(exp_time_out));
+   defparam 	exp_time_out_pin.IOSTANDARD  = "LVDS_25";
+
+   wire 	exp_user_in;
+   IBUFDS exp_user_in_pin (.O(exp_user_in),.I(exp_user_in_p),.IB(exp_user_in_n));
+   defparam 	exp_user_in_pin.IOSTANDARD = "LVDS_25";
    
-   wire 	exp_pps_out;
-   OBUFDS exp_pps_out_pin (.O(exp_pps_out_p),.OB(exp_pps_out_n),.I(exp_pps_out));
-   defparam 	exp_pps_out_pin.IOSTANDARD = "LVDS_25";
+   wire 	exp_user_out;
+   OBUFDS exp_user_out_pin (.O(exp_user_out_p),.OB(exp_user_out_n),.I(exp_user_out));
+   defparam 	exp_user_out_pin.IOSTANDARD  = "LVDS_25";
 
    reg [5:0] 	clock_ready_d;
-   always @(posedge aux_clk)
+   always @(posedge clk_fpga)
      clock_ready_d[5:0] <= {clock_ready_d[4:0],clock_ready};
-
    wire 	dcm_rst = ~&clock_ready_d & |clock_ready_d;
-   wire 	clk_muxed = clock_ready ? clk_fpga : aux_clk;
-
-   wire 	adc_on_a, adc_on_b, adc_oe_a, adc_oe_b;
-   assign 	adc_oen_a = ~adc_oe_a;
-   assign 	adc_oen_b = ~adc_oe_b;
-   assign 	adc_pdn_a = ~adc_on_a; 	
-   assign 	adc_pdn_b = ~adc_on_b; 	
 
+   // ADC A is inverted on the schematic to facilitate a clean layout
+   //  We account for that here by inverting it
+`ifdef LVDS
+   wire [13:0] 	adc_a, adc_a_inv, adc_b;
+   capture_ddrlvds #(.WIDTH(14)) capture_ddrlvds
+     (.clk(dsp_clk), .ssclk_p(ADC_clkout_p), .ssclk_n(ADC_clkout_n), 
+      .in_p({{ADCA_12_p, ADCA_10_p, ADCA_8_p, ADCA_6_p, ADCA_4_p, ADCA_2_p, ADCA_0_p},
+	     {ADCB_12_p, ADCB_10_p, ADCB_8_p, ADCB_6_p, ADCB_4_p, ADCB_2_p, ADCB_0_p}}), 
+      .in_n({{ADCA_12_n, ADCA_10_n, ADCA_8_n, ADCA_6_n, ADCA_4_n, ADCA_2_n, ADCA_0_n},
+	     {ADCB_12_n, ADCB_10_n, ADCB_8_n, ADCB_6_n, ADCB_4_n, ADCB_2_n, ADCB_0_n}}), 
+      .out({adc_a_inv,adc_b}));
+   assign adc_a = ~adc_a_inv;
+`else
+   reg [13:0] 	adc_a, adc_b;
+   always @(posedge dsp_clk)
+     begin
+	adc_a <= ~{ADCA_12_p,ADCA_12_n, ADCA_10_p,ADCA_10_n, ADCA_8_p,ADCA_8_n, ADCA_6_p,ADCA_6_n,
+		   ADCA_4_p,ADCA_4_n, ADCA_2_p,ADCA_2_n, ADCA_0_p,ADCA_0_n };
+	adc_b <= {ADCB_12_p,ADCB_12_n, ADCB_10_p,ADCB_10_n, ADCB_8_p,ADCB_8_n, ADCB_6_p,ADCB_6_n,
+		   ADCB_4_p,ADCB_4_n, ADCB_2_p,ADCB_2_n, ADCB_0_p,ADCB_0_n };
+     end
+`endif // !`ifdef LVDS
+   
    // Handle Clocks
    DCM DCM_INST (.CLKFB(dsp_clk), 
-                 .CLKIN(clk_muxed), 
+                 .CLKIN(clk_fpga), 
                  .DSSEN(0), 
                  .PSCLK(0), 
                  .PSEN(0), 
@@ -180,7 +196,7 @@ module u2plus
                  .CLK2X180(), 
                  .CLK90(), 
                  .CLK180(), 
-                 .CLK270(), 
+                 .CLK270(clk270_100), 
                  .LOCKED(LOCKED_OUT), 
                  .PSDONE(), 
                  .STATUS());
@@ -202,28 +218,43 @@ module u2plus
    BUFG dspclk_BUFG (.I(dcm_out), .O(dsp_clk));
    BUFG wbclk_BUFG (.I(clk_div), .O(wb_clk));
 
+   // Create clock for external SRAM thats -90degree phase to DSPCLK (i.e) 2nS earlier at 100MHz.
+   BUFG  clk270_100_buf_i1 (.I(clk270_100), 
+			    .O(clk270_100_buf));
+   OFDDRRSE RAM_CLK_i1 (.Q(RAM_CLK),
+			.C0(clk270_100_buf),
+			.C1(~clk270_100_buf),
+			.CE(1'b1),
+			.D0(1'b1),
+			.D1(1'b0),
+			.R(1'b0),
+			.S(1'b0));
+  
    // I2C -- Don't use external transistors for open drain, the FPGA implements this
    IOBUF scl_pin(.O(scl_pad_i), .IO(SCL), .I(scl_pad_o), .T(scl_pad_oen_o));
    IOBUF sda_pin(.O(sda_pad_i), .IO(SDA), .I(sda_pad_o), .T(sda_pad_oen_o));
 
    // LEDs are active low outputs
-   wire [4:0] leds_int;
-   assign     leds = ~leds_int;  // drive low to turn on leds
+   wire [5:0] leds_int;
+   assign     {ETH_LED,leds} = {6'b011111 ^ leds_int};  // drive low to turn on leds
    
    // SPI
-   wire 	miso, mosi, sclk_int;
-   assign 	{sclk,sdi} = (~sen_clk | ~sen_dac) ? {sclk_int,mosi} : 2'b0;
-   assign 	{sclk_tx_db,sdi_tx_db} = ~sen_tx_db ? {sclk_int,mosi} : 2'b0;
-   assign 	{sclk_tx_dac,sdi_tx_dac} = ~sen_tx_dac ? {sclk_int,mosi} : 2'b0;
-   assign 	{sclk_tx_adc,sdi_tx_adc} = ~sen_tx_adc ? {sclk_int,mosi} : 2'b0;
-   assign 	{sclk_rx_db,sdi_rx_db} = ~sen_rx_db ? {sclk_int,mosi} : 2'b0;
-   assign 	{sclk_rx_dac,sdi_rx_dac} = ~sen_rx_dac ? {sclk_int,mosi} : 2'b0;
-   assign 	{sclk_rx_adc,sdi_rx_adc} = ~sen_rx_adc ? {sclk_int,mosi} : 2'b0;
-   
-   assign 	miso = (~sen_clk & sdo) | (~sen_dac & sdo) | 
-		(~sen_tx_db & sdo_tx_db) | (~sen_tx_adc & sdo_tx_adc) |
-		(~sen_rx_db & sdo_rx_db) | (~sen_rx_adc & sdo_rx_adc);
+   wire       miso, mosi, sclk;
 
+   assign 	{SCLK_CLK,MOSI_CLK} 	   = ~SEN_CLK ? {sclk,mosi} : 2'B0;
+   assign 	{SCLK_DAC,MOSI_DAC} 	   = ~SEN_DAC ? {sclk,mosi} : 2'B0;
+   assign 	{SCLK_ADC,MOSI_ADC} 	   = ~SEN_ADC ? {sclk,mosi} : 2'B0;
+   assign 	{SCLK_TX_DB,MOSI_TX_DB}    = ~SEN_TX_DB ? {sclk,mosi} : 2'B0;
+   assign 	{SCLK_TX_DAC,MOSI_TX_DAC}  = ~SEN_TX_DAC ? {sclk,mosi} : 2'B0;
+   assign 	{SCLK_TX_ADC,MOSI_TX_ADC}  = ~SEN_TX_ADC ? {sclk,mosi} : 2'B0;
+   assign 	{SCLK_RX_DB,MOSI_RX_DB}    = ~SEN_RX_DB ? {sclk,mosi} : 2'B0;
+   assign 	{SCLK_RX_DAC,MOSI_RX_DAC}  = ~SEN_RX_DAC ? {sclk,mosi} : 2'B0;
+   assign 	{SCLK_RX_ADC,MOSI_RX_ADC}  = ~SEN_RX_ADC ? {sclk,mosi} : 2'B0;
+   
+   assign 	miso 			   = (~SEN_CLK & MISO_CLK) | (~SEN_DAC & MISO_DAC) |
+					     (~SEN_TX_DB & MISO_TX_DB) | (~SEN_TX_ADC & MISO_TX_ADC) |
+					     (~SEN_RX_DB & MISO_RX_DB) | (~SEN_RX_ADC & MISO_RX_ADC);
+   
    wire 	GMII_TX_EN_unreg, GMII_TX_ER_unreg;
    wire [7:0] 	GMII_TXD_unreg;
    wire 	GMII_GTX_CLK_int;
@@ -281,16 +312,53 @@ module u2plus
       .S(0)       // Synchronous preset input
       );
    */
-   u2_core u2_core(.dsp_clk           (dsp_clk),
+
+
+   //
+   // Instantiate IO for Bidirectional bus to SRAM
+   //
+   wire [35:0] RAM_D_pi;
+   wire [35:0] RAM_D_po;
+   wire        RAM_D_poe;
+   
+   genvar      i;
+   
+   generate  
+      for (i=0;i<36;i=i+1)
+        begin : gen_RAM_D_IO
+
+	   IOBUF #(
+		   .DRIVE(12),
+		   .IOSTANDARD("LVCMOS25"),
+		   .SLEW("FAST")
+		   )
+	     RAM_D_i (
+		      .O(RAM_D_pi[i]),
+		      .I(RAM_D_po[i]),
+		      .IO(RAM_D[i]),
+		      .T(RAM_D_poe)
+		      );
+	end // block: gen_RAM_D_IO
+   endgenerate
+
+   
+   
+   wire [15:0] dac_a_int, dac_b_int;
+   // DAC A and B are swapped in schematic to facilitate clean layout
+   // DAC A is also inverted in schematic to facilitate clean layout
+   always @(negedge dsp_clk) DACA <= ~dac_b_int;
+   always @(negedge dsp_clk) DACB <= dac_a_int;
+   
+   u2plus_core u2p_c(.dsp_clk           (dsp_clk),
 		     .wb_clk            (wb_clk),
 		     .clock_ready       (clock_ready),
-		     .clk_to_mac	(clk_to_mac),
-		     .pps_in		(pps_in),
+		     .clk_to_mac	(CLK_TO_MAC_int2),
+		     .pps_in		(PPS_IN),
 		     .leds		(leds_int),
 		     .debug		(debug[31:0]),
 		     .debug_clk		(debug_clk[1:0]),
-		     .exp_pps_in	(exp_pps_in),
-		     .exp_pps_out	(exp_pps_out),
+		     .exp_pps_in	(exp_time_in),
+		     .exp_pps_out	(exp_time_out),
 		     .GMII_COL		(GMII_COL),
 		     .GMII_CRS		(GMII_CRS),
 		     .GMII_TXD		(GMII_TXD_unreg[7:0]),
@@ -306,7 +374,6 @@ module u2plus
 		     .MDC		(MDC),
 		     .PHY_INTn		(PHY_INTn),
 		     .PHY_RESETn	(PHY_RESETn),
-		     .PHY_CLK		(PHY_CLK),
 		     .ser_enable	(ser_enable),
 		     .ser_prbsen	(ser_prbsen),
 		     .ser_loopen	(ser_loopen),
@@ -319,22 +386,16 @@ module u2plus
 		     .ser_r		(ser_r_int[15:0]),
 		     .ser_rklsb		(ser_rklsb_int),
 		     .ser_rkmsb		(ser_rkmsb_int),
-		     .cpld_start        (cpld_start),
-		     .cpld_mode         (cpld_mode),
-		     .cpld_done         (cpld_done),
-		     .cpld_din          (cpld_din),
-		     .cpld_clk          (cpld_clk),
-		     .cpld_detached     (cpld_detached),
 		     .adc_a		(adc_a[13:0]),
-		     .adc_ovf_a		(adc_ovf_a),
-		     .adc_on_a		(adc_on_a),
-		     .adc_oe_a		(adc_oe_a),
+		     .adc_ovf_a		(1'b0),
+		     .adc_on_a		(),
+		     .adc_oe_a		(),
 		     .adc_b		(adc_b[13:0]),
-		     .adc_ovf_b		(adc_ovf_b),
-		     .adc_on_b		(adc_on_b),
-		     .adc_oe_b		(adc_oe_b),
-		     .dac_a		(dac_a[15:0]),
-		     .dac_b		(dac_b[15:0]),
+		     .adc_ovf_b		(1'b0),
+		     .adc_on_b		(),
+		     .adc_oe_b		(),
+		     .dac_a		(dac_a_int[15:0]),
+		     .dac_b		(dac_b_int[15:0]),
 		     .scl_pad_i		(scl_pad_i),
 		     .scl_pad_o		(scl_pad_o),
 		     .scl_pad_oen_o	(scl_pad_oen_o),
@@ -345,33 +406,45 @@ module u2plus
 		     .clk_sel		(clk_sel[1:0]),
 		     .clk_func		(clk_func),
 		     .clk_status	(clk_status),
-		     .sclk		(sclk_int),
+		     .sclk		(sclk),
 		     .mosi		(mosi),
 		     .miso		(miso),
-		     .sen_clk		(sen_clk),
-		     .sen_dac		(sen_dac),
-		     .sen_tx_db		(sen_tx_db),
-		     .sen_tx_adc	(sen_tx_adc),
-		     .sen_tx_dac	(sen_tx_dac),
-		     .sen_rx_db		(sen_rx_db),
-		     .sen_rx_adc	(sen_rx_adc),
-		     .sen_rx_dac	(sen_rx_dac),
+		     .sen_clk		(SEN_CLK),
+		     .sen_dac		(SEN_DAC),
+		     .sen_adc           (SEN_ADC),
+		     .sen_tx_db		(SEN_TX_DB),
+		     .sen_tx_adc	(SEN_TX_ADC),
+		     .sen_tx_dac	(SEN_TX_DAC),
+		     .sen_rx_db		(SEN_RX_DB),
+		     .sen_rx_adc	(SEN_RX_ADC),
+		     .sen_rx_dac	(SEN_RX_DAC),
 		     .io_tx		(io_tx[15:0]),
 		     .io_rx		(io_rx[15:0]),
-		     .RAM_D             (RAM_D),
+		     .RAM_D_po          (RAM_D_po),
+		     .RAM_D_pi          (RAM_D_pi),
+		     .RAM_D_poe         (RAM_D_poe),
 		     .RAM_A             (RAM_A),
 		     .RAM_CE1n          (RAM_CE1n),
 		     .RAM_CENn          (RAM_CENn),
-		     .RAM_CLK           (RAM_CLK),
 		     .RAM_WEn           (RAM_WEn),
 		     .RAM_OEn           (RAM_OEn),
 		     .RAM_LDn           (RAM_LDn), 
-		     .uart_tx_o         (uart_tx_o),
-		     //.uart_rx_i         (uart_rx_i),
-		     .uart_rx_i         (),
+		     .uart_tx_o         (TXD[3:1]),
+		     .uart_rx_i         ({1'b1,RXD[3:1]}),
 		     .uart_baud_o       (),
 		     .sim_mode          (1'b0),
-		     .clock_divider     (2)
+		     .clock_divider     (2),
+		     .button            (FPGA_RESET),
+		     .spiflash_cs       (flash_cs),
+		     .spiflash_clk      (flash_clk),
+		     .spiflash_miso     (flash_miso),
+		     .spiflash_mosi     (flash_mosi)
 		     );
+
+   // Drive low so that RAM does not sleep.
+   assign RAM_ZZ = 0;
+   // Byte Writes are qualified by the global write enable
+   // Always do 36bit operations to extram.
+   assign RAM_BWn = 4'b0000;
    
 endmodule // u2plus