rtl: add uart rx function

Signed-off-by: liangkangnan <liangkangnan@163.com>
pull/1/head
liangkangnan 2020-06-26 22:40:44 +08:00
parent 405b3fb0c3
commit 4c6c044afb
3 changed files with 336 additions and 176 deletions

331
rtl/perips/uart.v Normal file
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@ -0,0 +1,331 @@
/*
Copyright 2020 Blue Liang, liangkangnan@163.com
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
// (: 115200, 8 N 1)
module uart(
input wire clk,
input wire rst,
input wire we_i,
input wire req_i,
input wire[31:0] addr_i,
input wire[31:0] data_i,
output reg[31:0] data_o,
output reg ack_o,
output wire tx_pin,
input wire rx_pin
);
// 50MHz115200bps
localparam BAUD_115200 = 32'h1B8;
localparam S_IDLE = 4'b0001;
localparam S_START = 4'b0010;
localparam S_SEND_BYTE = 4'b0100;
localparam S_STOP = 4'b1000;
reg tx_data_valid;
reg tx_data_ready;
reg[3:0] state;
reg[15:0] cycle_cnt;
reg[3:0] bit_cnt;
reg[7:0] tx_data;
reg tx_reg;
reg rx_q0;
reg rx_q1;
wire rx_negedge;
reg rx_start; // RX使
reg[3:0] rx_clk_edge_cnt; // clk沿
reg rx_clk_edge_level; // clk沿
reg rx_done;
reg[15:0] rx_clk_cnt;
reg[15:0] rx_div_cnt;
reg[7:0] rx_data;
reg rx_over;
localparam UART_CTRL = 8'h0;
localparam UART_STATUS = 8'h4;
localparam UART_BAUD = 8'h8;
localparam UART_TXDATA = 8'hc;
localparam UART_RXDATA = 8'h10;
// addr: 0x00
// rw. bit[0]: tx enable, 1 = enable, 0 = disable
// rw. bit[1]: rx enable, 1 = enable, 0 = disable
reg[31:0] uart_ctrl;
// addr: 0x04
// ro. bit[0]: tx busy, 1 = busy, 0 = idle
// rw. bit[1]: rx over, 1 = over, 0 = receiving
// must check this bit before tx data
reg[31:0] uart_status;
// addr: 0x08
// rw. clk div
reg[31:0] uart_baud;
// addr: 0x10
// ro. rx data
reg[31:0] uart_rx;
assign tx_pin = tx_reg;
//
always @ (posedge clk) begin
if (rst == 1'b0) begin
uart_ctrl <= 32'h0;
uart_status <= 32'h0;
uart_rx <= 32'h0;
uart_baud <= BAUD_115200;
tx_data_valid <= 1'b0;
end else begin
if (we_i == 1'b1) begin
case (addr_i[7:0])
UART_CTRL: begin
uart_ctrl <= data_i;
end
UART_BAUD: begin
uart_baud <= data_i;
end
UART_STATUS: begin
uart_status[1] <= data_i[1];
end
UART_TXDATA: begin
if (uart_ctrl[0] == 1'b1 && uart_status[0] == 1'b0) begin
tx_data <= data_i[7:0];
uart_status[0] <= 1'b1;
tx_data_valid <= 1'b1;
end
end
endcase
end else begin
tx_data_valid <= 1'b0;
if (tx_data_ready == 1'b1) begin
uart_status[0] <= 1'b0;
end
if (uart_ctrl[1] == 1'b1) begin
if (rx_over == 1'b1) begin
uart_status[1] <= 1'b1;
uart_rx <= {24'h0, rx_data};
end
end
end
end
end
//
always @ (*) begin
if (rst == 1'b0) begin
data_o = 32'h0;
end else begin
case (addr_i[7:0])
UART_CTRL: begin
data_o = uart_ctrl;
end
UART_STATUS: begin
data_o = uart_status;
end
UART_BAUD: begin
data_o = uart_baud;
end
UART_RXDATA: begin
data_o = uart_rx;
end
default: begin
data_o = 32'h0;
end
endcase
end
end
// *************************** TX ****************************
always @ (posedge clk) begin
if (rst == 1'b0) begin
state <= S_IDLE;
cycle_cnt <= 16'd0;
tx_reg <= 1'b0;
bit_cnt <= 4'd0;
tx_data_ready <= 1'b0;
end else begin
if (state == S_IDLE) begin
tx_reg <= 1'b1;
tx_data_ready <= 1'b0;
if (tx_data_valid == 1'b1) begin
state <= S_START;
cycle_cnt <= 16'd0;
bit_cnt <= 4'd0;
tx_reg <= 1'b0;
end
end else begin
cycle_cnt <= cycle_cnt + 16'd1;
if (cycle_cnt == uart_baud[15:0]) begin
cycle_cnt <= 16'd0;
case (state)
S_START: begin
tx_reg <= tx_data[bit_cnt];
state <= S_SEND_BYTE;
bit_cnt <= bit_cnt + 4'd1;
end
S_SEND_BYTE: begin
bit_cnt <= bit_cnt + 4'd1;
if (bit_cnt == 4'd8) begin
state <= S_STOP;
tx_reg <= 1'b1;
end else begin
tx_reg <= tx_data[bit_cnt];
end
end
S_STOP: begin
tx_reg <= 1'b1;
state <= S_IDLE;
tx_data_ready <= 1'b1;
end
endcase
end
end
end
end
// *************************** RX ****************************
// 沿()
assign rx_negedge = rx_q1 && ~rx_q0;
always @ (posedge clk) begin
if (rst == 1'b0) begin
rx_q0 <= 1'b0;
rx_q1 <= 1'b0;
end else begin
rx_q0 <= rx_pin;
rx_q1 <= rx_q0;
end
end
//
always @ (posedge clk) begin
if (rst == 1'b0) begin
rx_start <= 1'b0;
end else begin
if (uart_ctrl[1]) begin
if (rx_negedge) begin
rx_start <= 1'b1;
end else if (rx_clk_edge_cnt == 4'd9) begin
rx_start <= 1'b0;
end
end else begin
rx_start <= 1'b0;
end
end
end
always @ (posedge clk) begin
if (rst == 1'b0) begin
rx_div_cnt <= 16'h0;
end else begin
// 沿
if (rx_start == 1'b1 && rx_clk_edge_cnt == 4'h0) begin
rx_div_cnt <= {1'b0, uart_baud[15:1]};
end else begin
rx_div_cnt <= uart_baud[15:0];
end
end
end
//
always @ (posedge clk) begin
if (rst == 1'b0) begin
rx_clk_cnt <= 16'h0;
end else if (rx_start == 1'b1) begin
//
if (rx_clk_cnt == rx_div_cnt) begin
rx_clk_cnt <= 16'h0;
end else begin
rx_clk_cnt <= rx_clk_cnt + 1'b1;
end
end else begin
rx_clk_cnt <= 16'h0;
end
end
// 沿
always @ (posedge clk) begin
if (rst == 1'b0) begin
rx_clk_edge_cnt <= 4'h0;
rx_clk_edge_level <= 1'b0;
end else if (rx_start == 1'b1) begin
//
if (rx_clk_cnt == rx_div_cnt) begin
// 沿
if (rx_clk_edge_cnt == 4'd9) begin
rx_clk_edge_cnt <= 4'h0;
rx_clk_edge_level <= 1'b0;
end else begin
// 沿1
rx_clk_edge_cnt <= rx_clk_edge_cnt + 1'b1;
// 沿
rx_clk_edge_level <= 1'b1;
end
end else begin
rx_clk_edge_level <= 1'b0;
end
end else begin
rx_clk_edge_cnt <= 4'h0;
rx_clk_edge_level <= 1'b0;
end
end
// bit
always @ (posedge clk) begin
if (rst == 1'b0) begin
rx_data <= 8'h0;
rx_over <= 1'b0;
end else begin
if (rx_start == 1'b1) begin
// 沿
if (rx_clk_edge_level == 1'b1) begin
case (rx_clk_edge_cnt)
//
1: begin
end
//
2, 3, 4, 5, 6, 7, 8, 9: begin
rx_data <= rx_data | (rx_pin << (rx_clk_edge_cnt - 2));
//
if (rx_clk_edge_cnt == 4'h9) begin
rx_over <= 1'b1;
end
end
endcase
end
end else begin
rx_data <= 8'h0;
rx_over <= 1'b0;
end
end
end
endmodule

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@ -1,173 +0,0 @@
/*
Copyright 2020 Blue Liang, liangkangnan@163.com
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
module uart_tx(
input wire clk,
input wire rst,
input wire we_i,
input wire req_i,
input wire[31:0] addr_i,
input wire[31:0] data_i,
output reg[31:0] data_o,
output reg ack_o,
output wire tx_pin
);
localparam BAUD_115200 = 32'h1B8;
localparam S_IDLE = 4'b0001;
localparam S_START = 4'b0010;
localparam S_SEND_BYTE = 4'b0100;
localparam S_STOP = 4'b1000;
reg tx_data_valid;
reg tx_data_ready;
reg[3:0] state;
reg[15:0] cycle_cnt;
reg[3:0] bit_cnt;
reg[7:0] tx_data;
reg tx_reg;
localparam UART_CTRL = 4'h0;
localparam UART_STATUS = 4'h4;
localparam UART_BAUD = 4'h8;
localparam UART_TXDATA = 4'hc;
// addr: 0x00
// rw. bit[0]: tx enable, 1 = enable, 0 = disable
reg[31:0] uart_ctrl;
// addr: 0x04
// ro. bit[0]: tx busy, 1 = busy, 0 = idle
// must check this bit before tx data
reg[31:0] uart_status;
// addr: 0x08
// rw. clk div
reg[31:0] uart_baud;
assign tx_pin = tx_reg;
always @ (posedge clk) begin
if (rst == 1'b0) begin
uart_ctrl <= 32'h0;
uart_status <= 32'h0;
uart_baud <= BAUD_115200;
tx_data_valid <= 1'b0;
end else begin
if (we_i == 1'b1) begin
case (addr_i[3:0])
UART_CTRL: begin
uart_ctrl <= data_i;
end
UART_BAUD: begin
uart_baud <= data_i;
end
UART_TXDATA: begin
if (uart_ctrl[0] == 1'b1 && uart_status[0] == 1'b0) begin
tx_data <= data_i[7:0];
uart_status <= 32'h1;
tx_data_valid <= 1'b1;
end
end
endcase
end else begin
tx_data_valid <= 1'b0;
if (tx_data_ready == 1'b1) begin
uart_status <= 32'h0;
end
end
end
end
always @ (*) begin
if (rst == 1'b0) begin
data_o = 32'h0;
end else begin
case (addr_i[3:0])
UART_CTRL: begin
data_o = uart_ctrl;
end
UART_STATUS: begin
data_o = uart_status;
end
UART_BAUD: begin
data_o = uart_baud;
end
default: begin
data_o = 32'h0;
end
endcase
end
end
always @ (posedge clk) begin
if (rst == 1'b0) begin
state <= S_IDLE;
cycle_cnt <= 16'd0;
tx_reg <= 1'b0;
bit_cnt <= 4'd0;
tx_data_ready <= 1'b0;
end else begin
if (state == S_IDLE) begin
tx_reg <= 1'b1;
tx_data_ready <= 1'b0;
if (tx_data_valid == 1'b1) begin
state <= S_START;
cycle_cnt <= 16'd0;
bit_cnt <= 4'd0;
tx_reg <= 1'b0;
end
end else begin
cycle_cnt <= cycle_cnt + 16'd1;
if (cycle_cnt == uart_baud[15:0]) begin
cycle_cnt <= 16'd0;
case (state)
S_START: begin
tx_reg <= tx_data[bit_cnt];
state <= S_SEND_BYTE;
bit_cnt <= bit_cnt + 4'd1;
end
S_SEND_BYTE: begin
bit_cnt <= bit_cnt + 4'd1;
if (bit_cnt == 4'd8) begin
state <= S_STOP;
tx_reg <= 1'b1;
end else begin
tx_reg <= tx_data[bit_cnt];
end
end
S_STOP: begin
tx_reg <= 1'b1;
state <= S_IDLE;
tx_data_ready <= 1'b1;
end
endcase
end
end
end
end
endmodule

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@ -28,6 +28,7 @@ module tinyriscv_soc_top(
output wire halted_ind, // jtaghaltCPU
output wire tx_pin, // UART
input wire rx_pin, // UART
inout wire[1:0] gpio, // GPIO
input wire jtag_TCK, // JTAG TCK
@ -218,8 +219,8 @@ module tinyriscv_soc_top(
.ack_o(s2_ack_i)
);
// uart_tx
uart_tx uart_tx_0(
// uart
uart uart_0(
.clk(clk),
.rst(rst),
.we_i(s3_we_o),
@ -228,7 +229,8 @@ module tinyriscv_soc_top(
.data_i(s3_data_o),
.data_o(s3_data_i),
.ack_o(s3_ack_i),
.tx_pin(tx_pin)
.tx_pin(tx_pin),
.rx_pin(rx_pin)
);
// io0