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[/] [openmsp430/] [trunk/] [fpga/] [xilinx_diligent_s3board/] [rtl/] [verilog/] [omsp_uart.v] - Rev 158
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//---------------------------------------------------------------------------- // Copyright (C) 2009 , Olivier Girard // // Redistribution and use in source and binary forms, with or without // modification, are permitted provided that the following conditions // are met: // * Redistributions of source code must retain the above copyright // notice, this list of conditions and the following disclaimer. // * 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. // * Neither the name of the authors nor the names of its contributors // may be used to endorse or promote products derived from this software // without specific prior written permission. // // 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 HOLDER 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 ADVISED OF // THE POSSIBILITY OF SUCH DAMAGE // //---------------------------------------------------------------------------- // // *File Name: omsp_uart.v // // *Module Description: // Simple full duplex UART (8N1 protocol). // // *Author(s): // - Olivier Girard, olgirard@gmail.com // //---------------------------------------------------------------------------- // $Rev: 111 $ // $LastChangedBy: olivier.girard $ // $LastChangedDate: 2011-05-20 22:39:02 +0200 (Fri, 20 May 2011) $ //---------------------------------------------------------------------------- module omsp_uart ( // OUTPUTs irq_uart_rx, // UART receive interrupt irq_uart_tx, // UART transmit interrupt per_dout, // Peripheral data output uart_txd, // UART Data Transmit (TXD) // INPUTs mclk, // Main system clock per_addr, // Peripheral address per_din, // Peripheral data input per_en, // Peripheral enable (high active) per_we, // Peripheral write enable (high active) puc_rst, // Main system reset smclk_en, // SMCLK enable (from CPU) uart_rxd // UART Data Receive (RXD) ); // OUTPUTs //========= output irq_uart_rx; // UART receive interrupt output irq_uart_tx; // UART transmit interrupt output [15:0] per_dout; // Peripheral data output output uart_txd; // UART Data Transmit (TXD) // INPUTs //========= input mclk; // Main system clock input [13:0] per_addr; // Peripheral address input [15:0] per_din; // Peripheral data input input per_en; // Peripheral enable (high active) input [1:0] per_we; // Peripheral write enable (high active) input puc_rst; // Main system reset input smclk_en; // SMCLK enable (from CPU) input uart_rxd; // UART Data Receive (RXD) //============================================================================= // 1) PARAMETER DECLARATION //============================================================================= // Register base address (must be aligned to decoder bit width) parameter [14:0] BASE_ADDR = 15'h0080; // Decoder bit width (defines how many bits are considered for address decoding) parameter DEC_WD = 3; // Register addresses offset parameter [DEC_WD-1:0] CTRL = 'h0, STATUS = 'h1, BAUD_LO = 'h2, BAUD_HI = 'h3, DATA_TX = 'h4, DATA_RX = 'h5; // Register one-hot decoder utilities parameter DEC_SZ = 2**DEC_WD; parameter [DEC_SZ-1:0] BASE_REG = {{DEC_SZ-1{1'b0}}, 1'b1}; // Register one-hot decoder parameter [DEC_SZ-1:0] CTRL_D = (BASE_REG << CTRL), STATUS_D = (BASE_REG << STATUS), BAUD_LO_D = (BASE_REG << BAUD_LO), BAUD_HI_D = (BASE_REG << BAUD_HI), DATA_TX_D = (BASE_REG << DATA_TX), DATA_RX_D = (BASE_REG << DATA_RX); //============================================================================ // 2) REGISTER DECODER //============================================================================ // Local register selection wire reg_sel = per_en & (per_addr[13:DEC_WD-1]==BASE_ADDR[14:DEC_WD]); // Register local address wire [DEC_WD-1:0] reg_addr = {1'b0, per_addr[DEC_WD-2:0]}; // Register address decode wire [DEC_SZ-1:0] reg_dec = (CTRL_D & {DEC_SZ{(reg_addr==(CTRL >>1))}}) | (STATUS_D & {DEC_SZ{(reg_addr==(STATUS >>1))}}) | (BAUD_LO_D & {DEC_SZ{(reg_addr==(BAUD_LO >>1))}}) | (BAUD_HI_D & {DEC_SZ{(reg_addr==(BAUD_HI >>1))}}) | (DATA_TX_D & {DEC_SZ{(reg_addr==(DATA_TX >>1))}}) | (DATA_RX_D & {DEC_SZ{(reg_addr==(DATA_RX >>1))}}); // Read/Write probes wire reg_lo_write = per_we[0] & reg_sel; wire reg_hi_write = per_we[1] & reg_sel; wire reg_read = ~|per_we & reg_sel; // Read/Write vectors wire [DEC_SZ-1:0] reg_hi_wr = reg_dec & {DEC_SZ{reg_hi_write}}; wire [DEC_SZ-1:0] reg_lo_wr = reg_dec & {DEC_SZ{reg_lo_write}}; wire [DEC_SZ-1:0] reg_rd = reg_dec & {DEC_SZ{reg_read}}; //============================================================================ // 3) REGISTERS //============================================================================ // CTRL Register //----------------- reg [7:0] ctrl; wire ctrl_wr = CTRL[0] ? reg_hi_wr[CTRL] : reg_lo_wr[CTRL]; wire [7:0] ctrl_nxt = CTRL[0] ? per_din[15:8] : per_din[7:0]; always @ (posedge mclk or posedge puc_rst) if (puc_rst) ctrl <= 8'h00; else if (ctrl_wr) ctrl <= ctrl_nxt & 8'h73; wire ctrl_ien_tx_empty = ctrl[7]; wire ctrl_ien_tx = ctrl[6]; wire ctrl_ien_rx_ovflw = ctrl[5]; wire ctrl_ien_rx = ctrl[4]; wire ctrl_smclk_sel = ctrl[1]; wire ctrl_en = ctrl[0]; // STATUS Register //----------------- wire [7:0] status; reg status_tx_empty_pnd; reg status_tx_pnd; reg status_rx_ovflw_pnd; reg status_rx_pnd; wire status_tx_full; wire status_tx_busy; wire status_rx_busy; wire status_wr = STATUS[0] ? reg_hi_wr[STATUS] : reg_lo_wr[STATUS]; wire [7:0] status_nxt = STATUS[0] ? per_din[15:8] : per_din[7:0]; wire status_tx_empty_pnd_clr = status_wr & status_nxt[7]; wire status_tx_pnd_clr = status_wr & status_nxt[6]; wire status_rx_ovflw_pnd_clr = status_wr & status_nxt[5]; wire status_rx_pnd_clr = status_wr & status_nxt[4]; wire status_tx_empty_pnd_set; wire status_tx_pnd_set; wire status_rx_ovflw_pnd_set; wire status_rx_pnd_set; always @ (posedge mclk or posedge puc_rst) if (puc_rst) status_tx_empty_pnd <= 1'b0; else if (status_tx_empty_pnd_set) status_tx_empty_pnd <= 1'b1; else if (status_tx_empty_pnd_clr) status_tx_empty_pnd <= 1'b0; always @ (posedge mclk or posedge puc_rst) if (puc_rst) status_tx_pnd <= 1'b0; else if (status_tx_pnd_set) status_tx_pnd <= 1'b1; else if (status_tx_pnd_clr) status_tx_pnd <= 1'b0; always @ (posedge mclk or posedge puc_rst) if (puc_rst) status_rx_ovflw_pnd <= 1'b0; else if (status_rx_ovflw_pnd_set) status_rx_ovflw_pnd <= 1'b1; else if (status_rx_ovflw_pnd_clr) status_rx_ovflw_pnd <= 1'b0; always @ (posedge mclk or posedge puc_rst) if (puc_rst) status_rx_pnd <= 1'b0; else if (status_rx_pnd_set) status_rx_pnd <= 1'b1; else if (status_rx_pnd_clr) status_rx_pnd <= 1'b0; assign status = {status_tx_empty_pnd, status_tx_pnd, status_rx_ovflw_pnd, status_rx_pnd, status_tx_full, status_tx_busy, 1'b0, status_rx_busy}; // BAUD_LO Register //----------------- reg [7:0] baud_lo; wire baud_lo_wr = BAUD_LO[0] ? reg_hi_wr[BAUD_LO] : reg_lo_wr[BAUD_LO]; wire [7:0] baud_lo_nxt = BAUD_LO[0] ? per_din[15:8] : per_din[7:0]; always @ (posedge mclk or posedge puc_rst) if (puc_rst) baud_lo <= 8'h00; else if (baud_lo_wr) baud_lo <= baud_lo_nxt; // BAUD_HI Register //----------------- reg [7:0] baud_hi; wire baud_hi_wr = BAUD_HI[0] ? reg_hi_wr[BAUD_HI] : reg_lo_wr[BAUD_HI]; wire [7:0] baud_hi_nxt = BAUD_HI[0] ? per_din[15:8] : per_din[7:0]; always @ (posedge mclk or posedge puc_rst) if (puc_rst) baud_hi <= 8'h00; else if (baud_lo_wr) baud_hi <= baud_hi_nxt; wire [15:0] baudrate = {baud_hi, baud_lo}; // DATA_TX Register //----------------- reg [7:0] data_tx; wire data_tx_wr = DATA_TX[0] ? reg_hi_wr[DATA_TX] : reg_lo_wr[DATA_TX]; wire [7:0] data_tx_nxt = DATA_TX[0] ? per_din[15:8] : per_din[7:0]; always @ (posedge mclk or posedge puc_rst) if (puc_rst) data_tx <= 8'h00; else if (data_tx_wr) data_tx <= data_tx_nxt; // DATA_RX Register //----------------- reg [7:0] data_rx; reg [7:0] rxfer_buf; always @ (posedge mclk or posedge puc_rst) if (puc_rst) data_rx <= 8'h00; else if (status_rx_pnd_set) data_rx <= rxfer_buf; //============================================================================ // 4) DATA OUTPUT GENERATION //============================================================================ // Data output mux wire [15:0] ctrl_rd = {8'h00, (ctrl & {8{reg_rd[CTRL]}})} << (8 & {4{CTRL[0]}}); wire [15:0] status_rd = {8'h00, (status & {8{reg_rd[STATUS]}})} << (8 & {4{STATUS[0]}}); wire [15:0] baud_lo_rd = {8'h00, (baud_lo & {8{reg_rd[BAUD_LO]}})} << (8 & {4{BAUD_LO[0]}}); wire [15:0] baud_hi_rd = {8'h00, (baud_hi & {8{reg_rd[BAUD_HI]}})} << (8 & {4{BAUD_HI[0]}}); wire [15:0] data_tx_rd = {8'h00, (data_tx & {8{reg_rd[DATA_TX]}})} << (8 & {4{DATA_TX[0]}}); wire [15:0] data_rx_rd = {8'h00, (data_rx & {8{reg_rd[DATA_RX]}})} << (8 & {4{DATA_RX[0]}}); wire [15:0] per_dout = ctrl_rd | status_rd | baud_lo_rd | baud_hi_rd | data_tx_rd | data_rx_rd; //============================================================================= // 5) UART CLOCK SELECTION //============================================================================= wire uclk_en = ctrl_smclk_sel ? smclk_en : 1'b1; //============================================================================= // 5) UART RECEIVE LINE SYNCHRONIZTION & FILTERING //============================================================================= // Synchronize RXD input //-------------------------------- wire uart_rxd_sync_n; omsp_sync_cell sync_cell_uart_rxd ( .data_out (uart_rxd_sync_n), .clk (mclk), .data_in (~uart_rxd), .rst (puc_rst) ); wire uart_rxd_sync = ~uart_rxd_sync_n; // RXD input buffer //-------------------------------- reg [1:0] rxd_buf; always @ (posedge mclk or posedge puc_rst) if (puc_rst) rxd_buf <= 2'h3; else rxd_buf <= {rxd_buf[0], uart_rxd_sync}; // Majority decision //------------------------ reg rxd_maj; wire [1:0] rxd_maj_cnt = {1'b0, uart_rxd_sync} + {1'b0, rxd_buf[0]} + {1'b0, rxd_buf[1]}; wire rxd_maj_nxt = (rxd_maj_cnt>=2'b10); always @ (posedge mclk or posedge puc_rst) if (puc_rst) rxd_maj <= 1'b1; else rxd_maj <= rxd_maj_nxt; wire rxd_s = rxd_maj; wire rxd_fe = rxd_maj & ~rxd_maj_nxt; //============================================================================= // 6) UART RECEIVE //============================================================================= // RX Transfer counter //------------------------ reg [3:0] rxfer_bit; reg [15:0] rxfer_cnt; wire rxfer_start = (rxfer_bit==4'h0) & rxd_fe; wire rxfer_bit_inc = (rxfer_bit!=4'h0) & (rxfer_cnt=={16{1'b0}}); wire rxfer_done = (rxfer_bit==4'ha); always @ (posedge mclk or posedge puc_rst) if (puc_rst) rxfer_bit <= 4'h0; else if (~ctrl_en) rxfer_bit <= 4'h0; else if (rxfer_start) rxfer_bit <= 4'h1; else if (uclk_en) begin if (rxfer_done) rxfer_bit <= 4'h0; else if (rxfer_bit_inc) rxfer_bit <= rxfer_bit+4'h1; end always @ (posedge mclk or posedge puc_rst) if (puc_rst) rxfer_cnt <= {16{1'b0}}; else if (~ctrl_en) rxfer_cnt <= {16{1'b0}}; else if (rxfer_start) rxfer_cnt <= {1'b0, baudrate[15:1]}; else if (uclk_en) begin if (rxfer_bit_inc) rxfer_cnt <= baudrate; else if (|rxfer_cnt) rxfer_cnt <= rxfer_cnt+{16{1'b1}}; end // Receive buffer //------------------------- wire [7:0] rxfer_buf_nxt = {rxd_s, rxfer_buf[7:1]}; always @ (posedge mclk or posedge puc_rst) if (puc_rst) rxfer_buf <= 8'h00; else if (~ctrl_en) rxfer_buf <= 8'h00; else if (uclk_en) begin if (rxfer_bit_inc) rxfer_buf <= rxfer_buf_nxt; end // Status flags //------------------------- // Edge detection required for the case when // the transmit base clock is SMCLK reg rxfer_done_dly; always @ (posedge mclk or posedge puc_rst) if (puc_rst) rxfer_done_dly <= 1'b0; else rxfer_done_dly <= rxfer_done; assign status_rx_pnd_set = rxfer_done & ~rxfer_done_dly; assign status_rx_ovflw_pnd_set = status_rx_pnd_set & status_rx_pnd; assign status_rx_busy = (rxfer_bit!=4'h0); //============================================================================ // 5) UART TRANSMIT //============================================================================ // TX Transfer start detection //----------------------------- reg txfer_triggered; wire txfer_start; always @ (posedge mclk or posedge puc_rst) if (puc_rst) txfer_triggered <= 1'b0; else if (data_tx_wr) txfer_triggered <= 1'b1; else if (txfer_start) txfer_triggered <= 1'b0; // TX Transfer counter //------------------------ reg [3:0] txfer_bit; reg [15:0] txfer_cnt; assign txfer_start = (txfer_bit==4'h0) & txfer_triggered; wire txfer_bit_inc = (txfer_bit!=4'h0) & (txfer_cnt=={16{1'b0}}); wire txfer_done = (txfer_bit==4'hb); always @ (posedge mclk or posedge puc_rst) if (puc_rst) txfer_bit <= 4'h0; else if (~ctrl_en) txfer_bit <= 4'h0; else if (txfer_start) txfer_bit <= 4'h1; else if (uclk_en) begin if (txfer_done) txfer_bit <= 4'h0; else if (txfer_bit_inc) txfer_bit <= txfer_bit+4'h1; end always @ (posedge mclk or posedge puc_rst) if (puc_rst) txfer_cnt <= {16{1'b0}}; else if (~ctrl_en) txfer_cnt <= {16{1'b0}}; else if (txfer_start) txfer_cnt <= baudrate; else if (uclk_en) begin if (txfer_bit_inc) txfer_cnt <= baudrate; else if (|txfer_cnt) txfer_cnt <= txfer_cnt+{16{1'b1}}; end // Transmit buffer //------------------------- reg [8:0] txfer_buf; wire [8:0] txfer_buf_nxt = {1'b1, txfer_buf[8:1]}; always @ (posedge mclk or posedge puc_rst) if (puc_rst) txfer_buf <= 9'h1ff; else if (~ctrl_en) txfer_buf <= 9'h1ff; else if (txfer_start) txfer_buf <= {data_tx, 1'b0}; else if (uclk_en) begin if (txfer_bit_inc) txfer_buf <= txfer_buf_nxt; end assign uart_txd = txfer_buf[0]; // Status flags //------------------------- // Edge detection required for the case when // the transmit base clock is SMCLK reg txfer_done_dly; always @ (posedge mclk or posedge puc_rst) if (puc_rst) txfer_done_dly <= 1'b0; else txfer_done_dly <= txfer_done; assign status_tx_pnd_set = txfer_done & ~txfer_done_dly; assign status_tx_empty_pnd_set = status_tx_pnd_set & ~txfer_triggered; assign status_tx_busy = (txfer_bit!=4'h0) | txfer_triggered; assign status_tx_full = status_tx_busy & txfer_triggered; //============================================================================ // 6) INTERRUPTS //============================================================================ // Receive interrupt can be generated with the completion of a received byte // or an overflow occures. assign irq_uart_rx = (status_rx_pnd & ctrl_ien_rx) | (status_rx_ovflw_pnd & ctrl_ien_rx_ovflw); // Transmit interrupt can be generated with the transmition completion of // a byte or when the tranmit buffer is empty (i.e. nothing left to transmit) assign irq_uart_tx = (status_tx_pnd & ctrl_ien_tx) | (status_tx_empty_pnd & ctrl_ien_tx_empty); endmodule // uart
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