bugfixes for SD card compatibility in DMA mode

verilog/sd2snes/main.ucf

@@ -188,5 +188,7 @@ NET "SRAM_OE" IOSTANDARD = LVCMOS33;
 NET "SRAM_WE" IOSTANDARD = LVCMOS33;
 NET "SPI_DMA_CTRL" LOC = P41;
 NET "SPI_DMA_CTRL" IOSTANDARD = LVCMOS33;
+NET "SPI_DMA_CTRL" PULLUP;
 NET "SPI_SCK" IOSTANDARD = LVCMOS33;
-NET "SPI_SCK" PULLDOWN;
+NET "SPI_SCK" DRIVE = 16;
+NET "SPI_SCK" PULLUP;

verilog/sd2snes/spi_dma.v

@@ -41,7 +41,7 @@ reg [9:0] spi_dma_bytecnt;
 reg [3:0] spi_dma_clkcnt;
 reg [3:0] spi_dma_sck_int_r;
 reg [5:0] spi_dma_trig_r;
-reg [1:0] spi_dma_miso_r;
+reg [4:0] spi_dma_miso_r;
 reg spi_dma_sck_out_r;
 reg spi_dma_sck_out_r2;
 
@@ -62,23 +62,24 @@ end
 // synthesize clock
 wire spi_dma_sck_int = spi_dma_clkcnt[1];
 assign spi_dma_sck = spi_dma_sck_out_r & spi_dma_sck_out_r2;
+
 always @(posedge clk) begin
    spi_dma_clkcnt <= spi_dma_clkcnt + 1;
    spi_dma_sck_int_r <= {spi_dma_sck_int_r[2:0], spi_dma_sck_int};
    spi_dma_trig_r <= {spi_dma_trig_r[4:0], spi_dma_trig};
-   spi_dma_miso_r <= {spi_dma_miso_r[0], spi_dma_miso};
+   spi_dma_miso_r <= {spi_dma_miso_r[3:0], spi_dma_miso};
 end
 
 wire spi_dma_trig_rising = (spi_dma_trig_r[5:1] == 5'b00011);
 wire spi_dma_trig_falling = (spi_dma_trig_r[5:1] == 5'b11100);
-wire spi_dma_sck_rising = (spi_dma_sck_int_r[1:0] == 2'b01);
-wire spi_dma_sck_falling = (spi_dma_sck_int_r[1:0] == 2'b10);
-wire spi_dma_sck_rising2 = (spi_dma_sck_int_r[1:0] == 2'b01);
-wire spi_dma_sck_falling2 = (spi_dma_sck_int_r[1:0] == 2'b10);
+wire spi_dma_sck_rising = (spi_dma_sck_int_r[2:1] == 2'b01);
+wire spi_dma_sck_falling = (spi_dma_sck_int_r[2:1] == 2'b10);
+wire spi_dma_sck_rising2 = (spi_dma_sck_int_r[2:1] == 2'b01);
+wire spi_dma_sck_falling2 = (spi_dma_sck_int_r[2:1] == 2'b10);
 
-assign spi_dma_nextaddr = spi_dma_nextaddr_r;
+assign spi_dma_nextaddr = spi_dma_nextaddr_r & (spi_dma_bytecnt < 512);
 assign spi_dma_sram_data = spi_dma_sram_data_r;
-assign spi_dma_sram_we = spi_dma_sram_we_r;
+assign spi_dma_sram_we = spi_dma_sram_we_r | (spi_dma_bytecnt > 511);
 assign spi_dma_done = spi_dma_done_r;
 assign spi_dma_ovr = spi_dma_ovr_r;
 
@@ -86,7 +87,7 @@ always @(posedge clk) begin
    if (spi_dma_trig_falling & !spi_dma_ovr_r) begin
       spi_dma_done_r <= 0;
       spi_dma_ovr_r <= 1;
-   end else if (spi_dma_bitcnt == 0 && spi_dma_bytecnt == 512) begin
+   end else if (spi_dma_bitcnt == 0 && spi_dma_bytecnt == 514) begin
       spi_dma_done_r <= 1;
       spi_dma_ovr_r <= 0;
    end
@@ -99,30 +100,33 @@ always @(posedge clk) begin
       spi_dma_sck_out_r2 <= 1;
 end
 
-always @(posedge clk) begin
-   if (spi_dma_sck_rising & spi_dma_ovr_r & spi_dma_bitcnt < 8)
-      spi_dma_sram_data_r <= {spi_dma_sram_data_r[6:0], spi_dma_miso};
-end
+// fetch a little later
+//always @(posedge spi_dma_sck) begin
+//   if (/*spi_dma_sck_rising & */spi_dma_ovr_r & spi_dma_bitcnt <= 8)
+//      spi_dma_sram_data_r <= {spi_dma_sram_data_r[6:0], spi_dma_miso_r[0]};
+//end
 
 always @(posedge clk) begin
    if(spi_dma_sck_rising & spi_dma_ovr_r) begin
       if (spi_dma_bitcnt < 8) begin
          spi_dma_sck_out_r <= 1;
          spi_dma_bitcnt <= spi_dma_bitcnt + 1;
+         spi_dma_sram_data_r <= {spi_dma_sram_data_r[6:0], spi_dma_miso_r[0]};
       end else if (spi_dma_bitcnt == 8) begin
          spi_dma_sck_out_r <= 0;
          spi_dma_bitcnt <= spi_dma_bitcnt + 1;
-         spi_dma_sram_we_r <= 0;
+         spi_dma_sram_data_r <= {spi_dma_sram_data_r[6:0], spi_dma_miso_r[0]};
       end else if (spi_dma_bitcnt == 9) begin
          spi_dma_sck_out_r <= 0;
-         spi_dma_sram_we_r <= 1;
-         spi_dma_bytecnt <= spi_dma_bytecnt + 1;
+         spi_dma_sram_we_r <= 0;
          spi_dma_bitcnt <= 10;
       end else if (spi_dma_bitcnt == 10) begin
+         spi_dma_sram_we_r <= 1;
          spi_dma_nextaddr_r <= 1;
          spi_dma_bitcnt <= spi_dma_bitcnt + 1;
       end else if (spi_dma_bitcnt == 11) begin
          spi_dma_nextaddr_r <= 0;
+         spi_dma_bytecnt <= spi_dma_bytecnt + 1;
          spi_dma_bitcnt <= spi_dma_bitcnt + 1;
       end else if (spi_dma_bitcnt == 12) begin
          spi_dma_bitcnt <= 0;
@@ -134,7 +138,7 @@ always @(posedge clk) begin
       end else if (spi_dma_bitcnt == 4'b1111) begin
          spi_dma_bitcnt <= 0;
       end
-   end else if (spi_dma_sck_rising & !spi_dma_ovr_r) begin
+   end else if (spi_dma_trig_falling & !spi_dma_ovr_r) begin
       spi_dma_bitcnt <= 4'b1101;
       spi_dma_bytecnt <= 10'b0000000000;
    end