diff options
Diffstat (limited to 'src/rtl/uart_core.v')
| -rw-r--r-- | src/rtl/uart_core.v | 148 |
1 files changed, 74 insertions, 74 deletions
diff --git a/src/rtl/uart_core.v b/src/rtl/uart_core.v index 14a7ef7..eb62b17 100644 --- a/src/rtl/uart_core.v +++ b/src/rtl/uart_core.v @@ -3,9 +3,9 @@ // uart_core.v // ----------- // A simple universal asynchronous receiver/transmitter (UART) -// interface. The interface contains 16 byte wide transmit and -// receivea buffers and can handle start and stop bits. But in -// general is rather simple. The primary purpose is as host +// interface. The interface contains 16 byte wide transmit and +// receivea buffers and can handle start and stop bits. But in +// general is rather simple. The primary purpose is as host // interface for the coretest design. The core also has a // loopback mode to allow testing of a serial link. // @@ -17,30 +17,30 @@ // // Author: Joachim Strombergson // Copyright (c) 2014, SUNET -// -// Redistribution and use in source and binary forms, with or -// without modification, are permitted provided that the following -// conditions are met: -// -// 1. Redistributions of source code must retain the above copyright -// notice, this list of conditions and the following disclaimer. -// -// 2. Redistributions in binary form must reproduce the above copyright -// notice, this list of conditions and the following disclaimer in -// the documentation and/or other materials provided with the -// distribution. -// -// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS -// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT -// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS -// FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE -// COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, -// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, +// +// Redistribution and use in source and binary forms, with or +// without modification, are permitted provided that the following +// conditions are met: +// +// 1. Redistributions of source code must retain the above copyright +// notice, this list of conditions and the following disclaimer. +// +// 2. Redistributions in binary form must reproduce the above copyright +// notice, this list of conditions and the following disclaimer in +// the documentation and/or other materials provided with the +// distribution. +// +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS +// FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE +// COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, +// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, // BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; -// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER -// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, -// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) -// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF +// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER +// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, +// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) +// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF // ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. // //====================================================================== @@ -53,7 +53,7 @@ module uart_core( input wire [15 : 0] bit_rate, input wire [3 : 0] data_bits, input wire [1 : 0] stop_bits, - + // External data interface input wire rxd, output wire txd, @@ -62,30 +62,30 @@ module uart_core( output wire rxd_syn, output [7 : 0] rxd_data, input wire rxd_ack, - + // Internal transmit interface. input wire txd_syn, input wire [7 : 0] txd_data, output wire txd_ack ); - + //---------------------------------------------------------------- // Internal constant and parameter definitions. //---------------------------------------------------------------- - parameter ERX_IDLE = 0; + parameter ERX_IDLE = 0; parameter ERX_START = 1; parameter ERX_BITS = 2; parameter ERX_STOP = 3; parameter ERX_SYN = 4; - parameter ETX_IDLE = 0; + parameter ETX_IDLE = 0; parameter ETX_ACK = 1; parameter ETX_START = 2; parameter ETX_BITS = 3; parameter ETX_STOP = 4; - - + + //---------------------------------------------------------------- // Registers including update variables and write enable. //---------------------------------------------------------------- @@ -109,15 +109,15 @@ module uart_core( reg rxd_syn_reg; reg rxd_syn_new; reg rxd_syn_we; - + reg [2 : 0] erx_ctrl_reg; reg [2 : 0] erx_ctrl_new; reg erx_ctrl_we; - + reg txd_reg; reg txd_new; reg txd_we; - + reg [7 : 0] txd_byte_reg; reg [7 : 0] txd_byte_new; reg txd_byte_we; @@ -137,18 +137,18 @@ module uart_core( reg txd_ack_reg; reg txd_ack_new; reg txd_ack_we; - + reg [2 : 0] etx_ctrl_reg; reg [2 : 0] etx_ctrl_new; reg etx_ctrl_we; - + //---------------------------------------------------------------- // Wires. //---------------------------------------------------------------- wire [15 : 0] half_bit_rate; - - + + //---------------------------------------------------------------- // Concurrent connectivity for ports etc. //---------------------------------------------------------------- @@ -158,16 +158,16 @@ module uart_core( assign txd_ack = txd_ack_reg; assign half_bit_rate = {1'b0, bit_rate[15 : 1]}; - - + + //---------------------------------------------------------------- // reg_update // // Update functionality for all registers in the core. - // All registers are positive edge triggered with synchronous - // active low reset. All registers have write enable. + // All registers are positive edge triggered with + // asynchronous active low reset. //---------------------------------------------------------------- - always @ (posedge clk) + always @ (posedge clk or negedge reset_n) begin: reg_update if (!reset_n) begin @@ -177,7 +177,7 @@ module uart_core( rxd_bitrate_ctr_reg <= 16'h0000; rxd_syn_reg <= 0; erx_ctrl_reg <= ERX_IDLE; - + txd_reg <= 1; txd_byte_reg <= 8'h00; txd_bit_ctr_reg <= 4'h0; @@ -205,22 +205,22 @@ module uart_core( begin rxd_bitrate_ctr_reg <= rxd_bitrate_ctr_new; end - + if (rxd_syn_we) begin rxd_syn_reg <= rxd_syn_new; end - + if (erx_ctrl_we) begin erx_ctrl_reg <= erx_ctrl_new; end - + if (txd_we) begin txd_reg <= txd_new; end - + if (txd_byte_we) begin txd_byte_reg <= txd_byte_new; @@ -235,12 +235,12 @@ module uart_core( begin txd_bitrate_ctr_reg <= txd_bitrate_ctr_new; end - + if (txd_ack_we) begin txd_ack_reg <= txd_ack_new; end - + if (etx_ctrl_we) begin etx_ctrl_reg <= etx_ctrl_new; @@ -252,7 +252,7 @@ module uart_core( //---------------------------------------------------------------- // rxd_bit_ctr // - // Bit counter for receiving data on the external + // Bit counter for receiving data on the external // serial interface. //---------------------------------------------------------------- always @* @@ -277,7 +277,7 @@ module uart_core( //---------------------------------------------------------------- // rxd_bitrate_ctr // - // Bitrate counter for receiving data on the external + // Bitrate counter for receiving data on the external // serial interface. //---------------------------------------------------------------- always @* @@ -303,7 +303,7 @@ module uart_core( //---------------------------------------------------------------- // txd_bit_ctr // - // Bit counter for transmitting data on the external + // Bit counter for transmitting data on the external // serial interface. //---------------------------------------------------------------- always @* @@ -328,7 +328,7 @@ module uart_core( //---------------------------------------------------------------- // txd_bitrate_ctr // - // Bitrate counter for transmitting data on the external + // Bitrate counter for transmitting data on the external // serial interface. //---------------------------------------------------------------- always @* @@ -348,14 +348,14 @@ module uart_core( txd_bitrate_ctr_we = 1; end end // txd_bitrate_ctr - + //---------------------------------------------------------------- // external_rx_engine // - // Logic that implements the receive engine towards - // the external interface. Detects incoming data, collects it, - // if required checks parity and store correct data into + // Logic that implements the receive engine towards + // the external interface. Detects incoming data, collects it, + // if required checks parity and store correct data into // the rx buffer. //---------------------------------------------------------------- always @* @@ -369,7 +369,7 @@ module uart_core( rxd_syn_we = 0; erx_ctrl_new = ERX_IDLE; erx_ctrl_we = 0; - + case (erx_ctrl_reg) ERX_IDLE: begin @@ -405,7 +405,7 @@ module uart_core( end end - + ERX_BITS: begin if (rxd_bitrate_ctr_reg < bit_rate) @@ -425,7 +425,7 @@ module uart_core( end end - + ERX_STOP: begin rxd_bitrate_ctr_inc = 1; @@ -438,7 +438,7 @@ module uart_core( end end - + ERX_SYN: begin if (rxd_ack) @@ -450,7 +450,7 @@ module uart_core( end end - + default: begin @@ -462,7 +462,7 @@ module uart_core( //---------------------------------------------------------------- // external_tx_engine // - // Logic that implements the transmit engine towards + // Logic that implements the transmit engine towards // the external interface. //---------------------------------------------------------------- always @* @@ -497,7 +497,7 @@ module uart_core( end end - + ETX_ACK: begin if (!txd_syn) @@ -510,7 +510,7 @@ module uart_core( etx_ctrl_we = 1; end end - + ETX_START: begin if (txd_bitrate_ctr_reg == bit_rate) @@ -525,7 +525,7 @@ module uart_core( end end - + ETX_BITS: begin if (txd_bitrate_ctr_reg < bit_rate) @@ -535,7 +535,7 @@ module uart_core( else begin txd_bitrate_ctr_rst = 1; - + if (txd_bit_ctr_reg == data_bits) begin txd_new = 1; @@ -551,8 +551,8 @@ module uart_core( end end end - - + + ETX_STOP: begin txd_bitrate_ctr_inc = 1; @@ -563,14 +563,14 @@ module uart_core( end end - + default: begin end endcase // case (etx_ctrl_reg) end // external_tx_engine - + endmodule // uart //====================================================================== |