update readme

litex/readme.md

@@ -0,0 +1,59 @@
+# Litex
+
+## What is this firmware
+
+This firmware is generate on litex.
+
+[The LiteX framework provides a convenient and efficient infrastructure to create FPGA Cores/SoCs, to explore various digital design architectures and create full FPGA based systems.](https://github.com/enjoy-digital/litex)
+
+## How to use this firmware
+
+Flash this firmware into Tang Nano 20K, both GOWIN programmer or openFPGALoader works fine.
+
+Then open the serial port of Tang Nano 20K with 115200 baudrate, you can test the litex terminal
+
+## How to compile this firmware by myself
+
+Here we use ubuntu 20.04 as the system to compile this firmware.
+
+1. Get litex
+2. Install litex
+3. Get Gowin toolchain
+4. Compile the firmware
+
+### Get litex
+
+```bash
+mkdir ~/litex
+cd ~/litex
+wget https://raw.githubusercontent.com/enjoy-digital/litex/master/litex_setup.py
+```
+
+### Install litex
+
+```bash
+cd ~/litex
+chmod +x litex_setup.py
+python ./litex_setup.py --init --install --user `whoami` --config=full
+```
+
+### Get Gowin toolchain
+
+Get GOWIN IDE ([Chinese](http://www.gowinsemi.com.cn/faq.aspx) | [English](https://www.gowinsemi.com/en/support/download_eda/)).
+
+Here we use Education edition IDE as the example, make sure that your IDE is V1.9.8.11 version or newer. Otherwise you need license or your IDE does not support Tang Nano 20K FPGA Chip GW2AR-QN88C6I5
+
+```bash
+mkdir ~/gowin
+cd ~/gowin
+wget http://cdn.gowinsemi.com.cn/Gowin_V1.9.8.11_Education_linux.tar.gz
+tar zxvf Gowin_V1.9.8.11_Education_linux.tar.gz
+export PATH=~/gowin/IDE/bin:$PATH # Add gowin toolchain PATH
+```
+
+### Compile the firmware
+
+```bash
+cd ~/litex
+python3 -m litex_boards.targets.sipeed_tang_nano_20k --build
+```

ws2812/src/ws2812.v

@@ -1,46 +1,52 @@
 module top (
-	input 		clk,  //输入 时钟源  
+	input 		clk,  // input clock source
 
-	output reg WS2812 //输出到WS2812的接口
+	output reg WS2812 // output to the interface of WS2812
-	
 );
-parameter WS2812_NUM 	= 1  - 1     ; // WS2812的LED数量(1从0开始)
-parameter WS2812_WIDTH 	= 24 	     ; // WS2812的数据位宽
-parameter CLK_FRE 	 	= 27_000_000	 	 ; // CLK的频率(mHZ)
 
-parameter DELAY_1_HIGH 	= (CLK_FRE / 1_000_000 * 0.85 )  - 1; //≈850ns±150ns     1 高电平时间
+parameter WS2812_NUM 	= 0             ; // LED number of WS2812 (starts from 0)
-parameter DELAY_1_LOW 	= (CLK_FRE / 1_000_000 * 0.40 )  - 1; //≈400ns±150ns 	 1 低电平时间
+parameter WS2812_WIDTH 	= 24            ; // WS2812 data bit width
-parameter DELAY_0_HIGH 	= (CLK_FRE / 1_000_000 * 0.40 )  - 1; //≈400ns±150ns 	 0 高电平时间
+parameter CLK_FRE 	 	= 27_000_000    ; // CLK frequency (mHZ)
-parameter DELAY_0_LOW 	= (CLK_FRE / 1_000_000 * 0.85 )  - 1; //≈850ns±150ns     0 低电平时间
-parameter DELAY_RESET 	= (CLK_FRE / 10 ) - 1; //0.1s 复位时间 ＞50us
 
-parameter RESET 	 		= 0; //状态机声明
+parameter DELAY_1_HIGH 	= (CLK_FRE / 1_000_000 * 0.85 )  - 1; //≈850ns±150ns     1 high level time
+parameter DELAY_1_LOW 	= (CLK_FRE / 1_000_000 * 0.40 )  - 1; //≈400ns±150ns 	 1 low level time
+parameter DELAY_0_HIGH 	= (CLK_FRE / 1_000_000 * 0.40 )  - 1; //≈400ns±150ns 	 0 high level time
+parameter DELAY_0_LOW 	= (CLK_FRE / 1_000_000 * 0.85 )  - 1; //≈850ns±150ns     0 low level time
+parameter DELAY_RESET 	= (CLK_FRE / 10 ) - 1; //0.1s reset time ＞50us
+
+parameter RESET 	 		= 0; //state machine statement
 parameter DATA_SEND  		= 1;
 parameter BIT_SEND_HIGH   	= 2;
 parameter BIT_SEND_LOW   	= 3;
 
-reg [ 1:0] state       = 0; // synthesis preserve //主状态机控制
+parameter INIT_DATA = 24'b1111; // initial pattern
-reg [ 8:0] bit_send    = 0; // amount of bit sent // increase it for larger led strips/matrix
+
-reg [ 8:0] data_send   = 0; // amount of data sent // increase it for larger led strips/matrix
+reg [ 1:0] state       = 0; // synthesis preserve  - main state machine control
-reg [31:0] clk_count   = 0; // 延时控制
+reg [ 8:0] bit_send    = 0; // number of bits sent - increase for larger led strips/matrix
-reg [23:0] WS2812_data = 24'd1; // WS2812的颜色数据
+reg [ 8:0] data_send   = 0; // number of data sent - increase for larger led strips/matrix
+reg [31:0] clk_count   = 0; // delay control
+reg [23:0] WS2812_data = 0; // WS2812 color data
 
 always@(posedge clk)
 	case (state)
 		RESET:begin
 			WS2812 <= 0;
-
+			if (clk_count < DELAY_RESET) begin
-			if (clk_count < DELAY_RESET) 
 				clk_count <= clk_count + 1;
+            end
 			else begin
 				clk_count <= 0;
-				WS2812_data <= {WS2812_data[22:0],WS2812_data[23]};//颜色移位循环显示
+                if (WS2812_data == 0)
+                    WS2812_data <= INIT_DATA;
+                else
+                    WS2812_data <= {WS2812_data[22:0],WS2812_data[23]}; //color shift cycle display
 				state <= DATA_SEND;
 			end
 		end
 
 		DATA_SEND:
-			if (data_send == WS2812_NUM && bit_send == WS2812_WIDTH)begin 
+			if (data_send > WS2812_NUM && bit_send == WS2812_WIDTH)begin 
+                clk_count <= 0;
 				data_send <= 0;
 				bit_send  <= 0;
 				state <= RESET;
@@ -48,7 +54,7 @@ always@(posedge clk)
 			else if (bit_send < WS2812_WIDTH) begin
 				state    <= BIT_SEND_HIGH;
 			end
-			else begin// if (bit_send == WS2812_WIDTH)
+			else begin
 				data_send <= data_send + 1;
 				bit_send  <= 0;
 				state    <= BIT_SEND_HIGH;