Low-speed game gamepad support (#23)

Add support for 2 usb gamepads based on hi631's ukp code.
Add doc/usb_gamepad.md.

Author: nand2mario

doc/images/usb_gamepad1.jpg

@@ -0,0 +1,24 @@
+
+## USB Gamepad Setup
+
+NESTang 0.6 now supports USB gamepads, allowing you to use your existing controllers without the need to purchase new ones.
+
+<img src="images/usb_gamepad2.jpg" width=400>
+<img src="images/usb_gamepad1.jpg" width=400>
+
+To enable this functionality, you will need the following,
+* Two USB-A Female to 2.54mm adapters, which can be found [here](https://www.aliexpress.us/item/2255800203914149.html?spm=a2g0o.productlist.main.17.6e617e229i3qAm&algo_pvid=89ee64ce-a2c8-41f6-9e3b-45e8396569fd&algo_exp_id=89ee64ce-a2c8-41f6-9e3b-45e8396569fd-8&pdp_npi=4%40dis%21USD%210.28%210.25%21%21%210.28%21%21%402132a25516924371147167093ec531%2110000001592482118%21sea%21US%214484896846%21A&curPageLogUid=dAeFgl6FWDAf).
+* Four 15K ohm resistors as USB pulldown resistor.
+
+Then wire things up correctly, refer to the image above and the [Tang Nano 20K pinout](https://wiki.sipeed.com/hardware/en/tang/tang-nano-20k/nano-20k.html)). Follow these steps,
+* Connect USB VBUS to the 5V pin of Tang Nano 20K, and USB GND to the Tang GND.
+* For controller 1, connect D+ to pin 42 and D- to pin 41.
+* For controller 2, connect D+ to pin 56 and D- to pin 54.
+* Connect four 15K ohm resistors from D-/D+ to GND.
+
+Please note that using the resistors is necessary for stability.
+
+That's all you need to do.
+
+**Limitation**: Note that only USB low-speed gamepads are currently supported. So controllers like PS5 or Xbox 360 pads are not compatible.
+

doc/images/usb_gamepad2.jpg

@@ -16,6 +16,7 @@
         <File path="src/gowin_clkdiv/gowin_clkdiv.v" type="file.verilog" enable="1"/>
         <File path="src/gowin_rpll_hdmi/gowin_rpll.v" type="file.verilog" enable="1"/>
         <File path="src/gowin_rpll_nes/gowin_rpll.v" type="file.verilog" enable="1"/>
+        <File path="src/gowin_rpll_usb.v" type="file.verilog" enable="1"/>
         <File path="src/hdmi2/audio_clock_regeneration_packet.sv" type="file.verilog" enable="1"/>
         <File path="src/hdmi2/audio_info_frame.sv" type="file.verilog" enable="1"/>
         <File path="src/hdmi2/audio_sample_packet.sv" type="file.verilog" enable="1"/>
@@ -39,6 +40,8 @@
         <File path="src/sdcmd_ctrl.sv" type="file.verilog" enable="1"/>
         <File path="src/sdram.v" type="file.verilog" enable="1"/>
         <File path="src/uart_tx_V2.v" type="file.verilog" enable="1"/>
+        <File path="src/usb_gamepad.v" type="file.verilog" enable="1"/>
+        <File path="src/usb_gamepad_rom.v" type="file.verilog" enable="1"/>
         <File path="src/nestang.cst" type="file.cst" enable="1"/>
         <File path="src/nestang_dock.cst" type="file.cst" enable="0"/>
         <File path="src/nestang.sdc" type="file.sdc" enable="1"/>

doc/usb_gamepad.md

@@ -60,6 +60,6 @@ defparam rpll_inst.CLKOUTD_BYPASS = "false";
 defparam rpll_inst.DYN_SDIV_SEL = 2;
 defparam rpll_inst.CLKOUTD_SRC = "CLKOUT";
 defparam rpll_inst.CLKOUTD3_SRC = "CLKOUT";
-defparam rpll_inst.DEVICE = "GW2A-18C";
+defparam rpll_inst.DEVICE = "GW2AR-18";
 
 endmodule //Gowin_rPLL

nes.gprj

@@ -81,6 +81,6 @@ defparam rpll_inst.CLKOUTD_BYPASS = "false";
 defparam rpll_inst.DYN_SDIV_SEL = 2;
 defparam rpll_inst.CLKOUTD_SRC = "CLKOUT";
 defparam rpll_inst.CLKOUTD3_SRC = "CLKOUT";
-defparam rpll_inst.DEVICE = "GW2AR-18C";
+defparam rpll_inst.DEVICE = "GW2AR-18";
 
 endmodule //Gowin_rPLL

src/gowin_rpll_hdmi/gowin_rpll.v

@@ -0,0 +1,59 @@
+
+module Gowin_rPLL_usb (clkout, clkoutp, lock, reset, clkin);
+
+output clkout;
+output clkoutp;
+output lock;
+input reset;
+input clkin;
+
+wire clkoutd_o;
+wire clkoutd3_o;
+wire gw_gnd;
+
+assign gw_gnd = 1'b0;
+
+rPLL rpll_inst (
+    .CLKOUT(clkout),
+    .LOCK(lock),
+    .CLKOUTP(clkoutp),
+    .CLKOUTD(clkoutd_o),
+    .CLKOUTD3(clkoutd3_o),
+    .RESET(reset),
+    .RESET_P(gw_gnd),
+    .CLKIN(clkin),
+    .CLKFB(gw_gnd),
+    .FBDSEL({gw_gnd,gw_gnd,gw_gnd,gw_gnd,gw_gnd,gw_gnd}),
+    .IDSEL({gw_gnd,gw_gnd,gw_gnd,gw_gnd,gw_gnd,gw_gnd}),
+    .ODSEL({gw_gnd,gw_gnd,gw_gnd,gw_gnd,gw_gnd,gw_gnd}),
+    .PSDA({gw_gnd,gw_gnd,gw_gnd,gw_gnd}),
+    .DUTYDA({gw_gnd,gw_gnd,gw_gnd,gw_gnd}),
+    .FDLY({gw_gnd,gw_gnd,gw_gnd,gw_gnd})
+);
+
+// 27 -> 12 Mhz low-speed USB clock
+defparam rpll_inst.FCLKIN = "27";
+defparam rpll_inst.IDIV_SEL = 8;
+defparam rpll_inst.FBDIV_SEL = 3;
+defparam rpll_inst.ODIV_SEL = 64;
+
+defparam rpll_inst.DYN_IDIV_SEL = "false";
+defparam rpll_inst.DYN_FBDIV_SEL = "false";
+defparam rpll_inst.DYN_ODIV_SEL = "false";
+defparam rpll_inst.PSDA_SEL = "1000";
+defparam rpll_inst.DYN_DA_EN = "false";
+defparam rpll_inst.DUTYDA_SEL = "1000";
+defparam rpll_inst.CLKOUT_FT_DIR = 1'b1;
+defparam rpll_inst.CLKOUTP_FT_DIR = 1'b1;
+defparam rpll_inst.CLKOUT_DLY_STEP = 0;
+defparam rpll_inst.CLKOUTP_DLY_STEP = 0;
+defparam rpll_inst.CLKFB_SEL = "internal";
+defparam rpll_inst.CLKOUT_BYPASS = "false";
+defparam rpll_inst.CLKOUTP_BYPASS = "false";
+defparam rpll_inst.CLKOUTD_BYPASS = "false";
+defparam rpll_inst.DYN_SDIV_SEL = 2;
+defparam rpll_inst.CLKOUTD_SRC = "CLKOUT";
+defparam rpll_inst.CLKOUTD3_SRC = "CLKOUT";
+defparam rpll_inst.DEVICE = "GW2AR-18";
+
+endmodule //Gowin_rPLL

src/gowin_rpll_nes/gowin_rpll.v

@@ -49,6 +49,13 @@ module NES_Tang20k(
     input joystick_miso2,
     output reg joystick_cs2,
 
+    // USB
+    inout usbdm,
+    inout usbdp,
+    inout usbdm2,
+    inout usbdp2,
+//    output clk_usb,
+
     // HDMI TX
     output       tmds_clk_n,
     output       tmds_clk_p,
@@ -64,12 +71,21 @@ always @(posedge clk) begin
 end
 
 `ifndef VERILATOR
-// NES PPU clock 5.369 * 7 = 37.6
-Gowin_rPLL_nes pll_nes(
-    .clkin(sys_clk),
-    .clkout(clk),          // FREQ main clock
-    .clkoutp(clk_sdram)    // FREQ main clock phase shifted
-);
+// Gowin_rPLL_nes pll_nes(
+//     .clkin(sys_clk),
+//     .clkout(clk),          // FREQ main clock
+//     .clkoutp(clk_sdram)    // FREQ main clock phase shifted
+// );
+  wire clk = sys_clk;
+  wire clk_sdram = ~sys_clk;  
+  wire clk_usb;
+
+  // USB clock 12Mhz
+  Gowin_rPLL_usb pll_nes(
+      .clkin(sys_clk),
+      .clkout(clk_usb),       // 12Mhz usb clock
+      .clkoutp()
+  );
 
   // HDMI domain clocks
   wire clk_p;     // 720p pixel clock: 74.25 Mhz
@@ -161,11 +177,16 @@ UartDemux #(.FREQ(FREQ), .BAUDRATE(BAUDRATE)) uart_demux(
   O is A, X is B
   */
   wire [7:0] joy_rx[0:1], joy_rx2[0:1];     // 6 RX bytes for all button/axis state
+  wire [7:0] usb_btn, usb_btn2;
+  wire usb_btn_x, usb_btn_y, usb_btn_x2, usb_btn_y2;
+  wire usb_conerr, usb_conerr2;
   wire auto_square, auto_triangle, auto_square2, auto_triangle2;
   wire [7:0] nes_btn = {~joy_rx[0][5], ~joy_rx[0][7], ~joy_rx[0][6], ~joy_rx[0][4], 
-                         ~joy_rx[0][3], ~joy_rx[0][0], ~joy_rx[1][6] | auto_square, ~joy_rx[1][5] | auto_triangle};
+                        ~joy_rx[0][3], ~joy_rx[0][0], ~joy_rx[1][6] | auto_square, ~joy_rx[1][5] | auto_triangle} |
+                         usb_btn;
   wire [7:0] nes_btn2 = {~joy_rx2[0][5], ~joy_rx2[0][7], ~joy_rx2[0][6], ~joy_rx2[0][4], 
-                         ~joy_rx2[0][3], ~joy_rx2[0][0], ~joy_rx2[1][6] | auto_square2, ~joy_rx2[1][5] | auto_triangle2};
+                         ~joy_rx2[0][3], ~joy_rx2[0][0], ~joy_rx2[1][6] | auto_square2, ~joy_rx2[1][5] | auto_triangle2} |
+                         usb_btn2;
 
   // Joypad handling
   always @(posedge clk) begin
@@ -349,18 +370,32 @@ dualshock_controller controller2 (
     .I_VIB_SW(2'b00), .I_VIB_DAT(8'hff)     // no vibration
 );
 
-Autofire af_square (.clk(clk), .resetn(sys_resetn), .btn(~joy_rx[1][7]), .out(auto_square));
-Autofire af_triangle (.clk(clk), .resetn(sys_resetn), .btn(~joy_rx[1][4]), .out(auto_triangle));
-Autofire af_square2 (.clk(clk), .resetn(sys_resetn), .btn(~joy_rx2[1][7]), .out(auto_square2));
-Autofire af_triangle2 (.clk(clk), .resetn(sys_resetn), .btn(~joy_rx2[1][4]), .out(auto_triangle2));
+Autofire af_square (.clk(clk), .resetn(sys_resetn), .btn(~joy_rx[1][7] | usb_btn_y), .out(auto_square));            // B
+Autofire af_triangle (.clk(clk), .resetn(sys_resetn), .btn(~joy_rx[1][4] | usb_btn_x), .out(auto_triangle));        // A
+Autofire af_square2 (.clk(clk), .resetn(sys_resetn), .btn(~joy_rx2[1][7] | usb_btn_y2), .out(auto_square2));
+Autofire af_triangle2 (.clk(clk), .resetn(sys_resetn), .btn(~joy_rx2[1][4] | usb_btn_x2), .out(auto_triangle2));
+
+wire [63:0] dbg_hid_report;
+wire [3:0] dbg_dev;
+wire [15:0] dbg_vid, dbg_pid;
+usb_gamepad usb_controller (
+    .usbclk(clk_usb), .usbrst_n(sys_resetn),
+    .usb_dm(usbdm), .usb_dp(usbdp),	.btn_nes(usb_btn), .btn_x(usb_btn_x), .btn_y(usb_btn_y), .conerr(usb_conerr),
+    .dbg_hid_report(), .dbg_dev(), .dbg_vid(), .dbg_pid()
+);
+usb_gamepad usb_controller2 (
+    .usbclk(clk_usb), .usbrst_n(sys_resetn),
+    .usb_dm(usbdm2), .usb_dp(usbdp2), .btn_nes(usb_btn2), .btn_x(usb_btn_x2), .btn_y(usb_btn_y2), .conerr(usb_conerr2),
+    .dbg_hid_report(dbg_hid_report), .dbg_dev(dbg_dev), .dbg_vid(dbg_vid), .dbg_pid(dbg_pid)
+);
 
 //
 // Print control
 //
 `include "print.v"
 defparam tx.uart_freq=BAUDRATE;
 defparam tx.clk_freq=FREQ;
-assign print_clk = clk;
+assign print_clk = sys_clk;
 assign UART_TXD = uart_txp;
 
 reg[3:0] state_0;
@@ -378,23 +413,15 @@ reg [15:0] indata_clk_count = 0;
 
 reg [3:0] sd_state0 = 0;
 
-reg [19:0] timer;           // 27 times per second
+reg [19:0] timer;           // 37 times per second
 always @(posedge clk) timer <= timer + 1;
 
+// `define HID_REPORT
+
 always@(posedge clk)begin
     state_0<={2'b0, loader_done};
     state_1<=state_0;
 
-/*
-    if (timer == 0) begin
-        `print({joy_rx[0], joy_rx[1], joy_rx2[0], joy_rx2[1], nes_btn, nes_btn2}, 6);
-//        `print({3'b0, sd_active, 3'b0, sd_total, sd_rsector, sd_last_sector}, 8);
-    end
-    if (timer == 20'b1000_0000_0000_0000_0000) begin
-        `print("\n", STR);
-    end
-*/
-
     if (uart_demux.write)
         recv_packets <= recv_packets + 1;        
 
@@ -407,18 +434,46 @@ always@(posedge clk)begin
         end
     end
 
-//    if (sd_state != sd_state0) begin
-//        if (sd_state == SD_READ_META) begin
-//            `print("Reading SDcard\n", STR);
-//        end
-//        if (sd_state == SD_START_SECTOR) begin
-//            if (sd_rsector[15:0] == 16'b0) begin
-//                `print(sd_romlen, 3);
-//            end else 
-//                `print(sd_rsector[15:0], 2);
-//        end
-//        sd_state0 <= sd_state;
-//    end
+`ifdef HID_REPORT
+    if (timer == 20'h00000)
+      `print("hid=", STR);
+    if (timer == 20'h10000)
+      `print(dbg_hid_report, 8);
+    if (timer == 20'h20000)
+      `print(", vidpid=", STR);
+    if (timer == 20'h30000)
+      `print({dbg_vid, dbg_pid}, 4);
+    if (timer == 20'h40000)
+      `print(", dev=", STR);
+    if (timer == 20'h50000)
+      `print({4'b0, dbg_dev}, 1);
+    if (timer == 20'h60000)
+      `print(", ds2[2]=", STR);
+    if (timer == 20'h70000)
+      `print({joy_rx[0], joy_rx[1], joy_rx2[0], joy_rx2[1]}, 4);
+    if (timer == 20'h80000)
+      `print(", usb_btn[2]=", STR);
+    if (timer == 20'h90000)
+      `print({usb_btn, usb_btn2}, 2);
+
+    if (timer == 20'hf0000)
+      `print("\n", STR);
+`endif
+
+`ifdef PRINT_SD
+    if (sd_state != sd_state0) begin
+        if (sd_state == SD_READ_META) begin
+            `print("Reading SDcard\n", STR);
+        end
+        if (sd_state == SD_START_SECTOR) begin
+            if (sd_rsector[15:0] == 16'b0) begin
+                `print(sd_romlen, 3);
+            end else 
+                `print(sd_rsector[15:0], 2);
+        end
+        sd_state0 <= sd_state;
+    end
+`endif
 
 `ifdef COLOR_TRACING
     // print some color values
@@ -490,6 +545,7 @@ end
 
 `endif
 
-assign led = ~{~UART_RXD, loader_done};
+assign led = ~{~UART_RXD, usb_conerr, loader_done};
+// assign led = ~usb_btn;
 
 endmodule

src/gowin_rpll_usb.v

@@ -3,6 +3,7 @@ localparam FREQ=27_000_000;          // at least 10x baudrate
 // localparam FREQ=37_800_000;
 
 // UART baudrate: BAUDRATE <= FREQ/10
+// localparam BAUDRATE=115200;
 localparam BAUDRATE=921600;
 
 // define this to execute one NES cycle per 0.01 second and print the operation done

src/nes_tang20k.v

@@ -71,9 +71,30 @@ IO_PORT "UART_TXD" IO_TYPE=LVCMOS33;
 //IO_LOC "UART_RXD" 31;
 //IO_PORT "UART_RXD" IO_TYPE=LVCMOS33 PULL_MODE=NONE;
 
+// USB ports
+IO_LOC "usbdp" 42;      
+IO_PORT "usbdp" PULL_MODE=DOWN IO_TYPE=LVCMOS33;
+IO_LOC "usbdm" 41;      
+IO_PORT "usbdm" PULL_MODE=DOWN IO_TYPE=LVCMOS33;
+IO_LOC "usbdp2" 56;     
+IO_PORT "usbdp2" PULL_MODE=DOWN IO_TYPE=LVCMOS33;
+IO_LOC "usbdm2" 54;     
+IO_PORT "usbdm2" PULL_MODE=DOWN IO_TYPE=LVCMOS33;
+
+// USB debug board
+//IO_LOC "usbdp" 41;      // LCD_R4
+//IO_PORT "usbdp" PULL_MODE=DOWN IO_TYPE=LVCMOS33;
+//IO_LOC "usbdm" 42;      // LCD_R3
+//IO_PORT "usbdm" PULL_MODE=DOWN IO_TYPE=LVCMOS33;
+//IO_LOC "clk_usb" 56;    // for logic analyzer
+//IO_PORT "clk_usb" PULL_MODE=NONE IO_TYPE=LVCMOS33;
+
+
 // 2 LEDs for debug
 IO_LOC "led[1]" 16;
 IO_PORT "led[1]" IO_TYPE=LVCMOS33 PULL_MODE=UP DRIVE=8;
 IO_LOC "led[0]" 15;
 IO_PORT "led[0]" IO_TYPE=LVCMOS33 PULL_MODE=UP DRIVE=8;
 
+
+// pinout: https://wiki.sipeed.com/hardware/zh/tang/tang-nano-20k/assets/nano_20k/tang_nano_20k_pinlabel.png

src/nes_tang20k.vh

@@ -1,8 +1,11 @@
 
 // NES clocks
-create_clock -name clk -period 37.04 [get_nets {clk}]       // 27 Mhz
+create_clock -name clk -period 37.04 [get_nets {sys_clk}]       // 27 Mhz
 //create_generated_clock -name clk -source [get_nets {pclk}] -master_clock pclk -divide_by 3 [get_nets {clk}]     // 32.25 Mhz
 
+// USB clock
+create_clock -name clk_usb -period 83.33 [get_nets {clk_usb}]       // 12 Mhz
+
 // HDMI clocks
 create_clock -name clk_p5 -period 2.6936 [get_nets {clk_p5}]                    // 371.25 Mhz
 //create_generated_clock -name clk_p -source [get_nets {clk_p}] -master_clock clk_p5 -divide_by 5 [get_nets {clk_p}]     // 74.25 Mhz: 720p pixel clock