//---------------------------------------------------------------------------- // Copyright (C) 2001 Authors // // This source file may be used and distributed without restriction provided // that this copyright statement is not removed from the file and that any // derivative work contains the original copyright notice and the associated // disclaimer. // // This source file is free software; you can redistribute it and/or modify // it under the terms of the GNU Lesser General Public License as published // by the Free Software Foundation; either version 2.1 of the License, or // (at your option) any later version. // // This source is distributed in the hope that it will be useful, but WITHOUT // ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or // FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public // License for more details. // // You should have received a copy of the GNU Lesser General Public License // along with this source; if not, write to the Free Software Foundation, // Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA // //---------------------------------------------------------------------------- // // *File Name: omsp_clock_module.v // // *Module Description: // Basic clock module implementation. // Since the openMSP430 mainly targets FPGA and hobby // designers. The clock structure has been greatly // symplified in order to ease integration. // See online wiki for more info. // // *Author(s): // - Olivier Girard, olgirard@gmail.com // //---------------------------------------------------------------------------- // $Rev: 34 $ // $LastChangedBy: olivier.girard $ // $LastChangedDate: 2009-12-29 20:10:34 +0100 (Tue, 29 Dec 2009) $ //---------------------------------------------------------------------------- `include "timescale.v" `include "openMSP430_defines.v" module omsp_clock_module ( // OUTPUTs aclk_en, // ACLK enable mclk, // Main system clock per_dout, // Peripheral data output por, // Power-on reset puc, // Main system reset smclk_en, // SMCLK enable // INPUTs dbg_reset, // Reset CPU from debug interface dco_clk, // Fast oscillator (fast clock) lfxt_clk, // Low frequency oscillator (typ 32kHz) oscoff, // Turns off LFXT1 clock input per_addr, // Peripheral address per_din, // Peripheral data input per_en, // Peripheral enable (high active) per_wen, // Peripheral write enable (high active) reset_n, // Reset Pin (low active) scg1, // System clock generator 1. Turns off the SMCLK wdt_reset // Watchdog-timer reset ); // OUTPUTs //========= output aclk_en; // ACLK enable output mclk; // Main system clock output [15:0] per_dout; // Peripheral data output output por; // Power-on reset output puc; // Main system reset output smclk_en; // SMCLK enable // INPUTs //========= input dbg_reset; // Reset CPU from debug interface input dco_clk; // Fast oscillator (fast clock) input lfxt_clk; // Low frequency oscillator (typ 32kHz) input oscoff; // Turns off LFXT1 clock input input [7:0] per_addr; // Peripheral address input [15:0] per_din; // Peripheral data input input per_en; // Peripheral enable (high active) input [1:0] per_wen; // Peripheral write enable (high active) input reset_n; // Reset Pin (low active) input scg1; // System clock generator 1. Turns off the SMCLK input wdt_reset; // Watchdog-timer reset //============================================================================= // 1) PARAMETER DECLARATION //============================================================================= // Register addresses parameter BCSCTL1 = 9'h057; parameter BCSCTL2 = 9'h058; // Register one-hot decoder parameter BCSCTL1_D = (256'h1 << (BCSCTL1 /2)); parameter BCSCTL2_D = (256'h1 << (BCSCTL2 /2)); //============================================================================ // 2) REGISTER DECODER //============================================================================ // Register address decode reg [255:0] reg_dec; always @(per_addr) case (per_addr) (BCSCTL1 /2): reg_dec = BCSCTL1_D; (BCSCTL2 /2): reg_dec = BCSCTL2_D; default : reg_dec = {256{1'b0}}; endcase // Read/Write probes wire reg_lo_write = per_wen[0] & per_en; wire reg_hi_write = per_wen[1] & per_en; wire reg_read = ~|per_wen & per_en; // Read/Write vectors wire [255:0] reg_hi_wr = reg_dec & {256{reg_hi_write}}; wire [255:0] reg_lo_wr = reg_dec & {256{reg_lo_write}}; wire [255:0] reg_rd = reg_dec & {256{reg_read}}; //============================================================================ // 3) REGISTERS //============================================================================ // BCSCTL1 Register //-------------- reg [7:0] bcsctl1; wire bcsctl1_wr = BCSCTL1[0] ? reg_hi_wr[BCSCTL1/2] : reg_lo_wr[BCSCTL1/2]; wire [7:0] bcsctl1_nxt = BCSCTL1[0] ? per_din[15:8] : per_din[7:0]; always @ (posedge mclk or posedge puc) if (puc) bcsctl1 <= 8'h00; else if (bcsctl1_wr) bcsctl1 <= bcsctl1_nxt & 8'h30; // Mask unused bits // BCSCTL2 Register //-------------- reg [7:0] bcsctl2; wire bcsctl2_wr = BCSCTL2[0] ? reg_hi_wr[BCSCTL2/2] : reg_lo_wr[BCSCTL2/2]; wire [7:0] bcsctl2_nxt = BCSCTL2[0] ? per_din[15:8] : per_din[7:0]; always @ (posedge mclk or posedge puc) if (puc) bcsctl2 <= 8'h00; else if (bcsctl2_wr) bcsctl2 <= bcsctl2_nxt & 8'h0e; // Mask unused bits //============================================================================ // 4) DATA OUTPUT GENERATION //============================================================================ // Data output mux wire [15:0] bcsctl1_rd = (bcsctl1 & {8{reg_rd[BCSCTL1/2]}}) << (8 & {4{BCSCTL1[0]}}); wire [15:0] bcsctl2_rd = (bcsctl2 & {8{reg_rd[BCSCTL2/2]}}) << (8 & {4{BCSCTL2[0]}}); wire [15:0] per_dout = bcsctl1_rd | bcsctl2_rd; //============================================================================= // 5) CLOCK GENERATION //============================================================================= // Synchronize LFXT_CLK & edge detection //--------------------------------------- reg [2:0] lfxt_clk_s; always @ (posedge mclk or posedge puc) if (puc) lfxt_clk_s <= 3'b000; else lfxt_clk_s <= {lfxt_clk_s[1:0], lfxt_clk}; wire lfxt_clk_en = (lfxt_clk_s[1] & ~lfxt_clk_s[2]) & ~(oscoff & ~bcsctl2[`SELS]); // Generate main system clock //---------------------------- wire mclk = dco_clk; wire mclk_n = !dco_clk; // Generate ACLK //---------------------------- reg [2:0] aclk_div; wire aclk_en = lfxt_clk_en & ((bcsctl1[`DIVAx]==2'b00) ? 1'b1 : (bcsctl1[`DIVAx]==2'b01) ? aclk_div[0] : (bcsctl1[`DIVAx]==2'b10) ? &aclk_div[1:0] : &aclk_div[2:0]); always @ (posedge mclk or posedge puc) if (puc) aclk_div <= 3'h0; else if ((bcsctl1[`DIVAx]!=2'b00) & lfxt_clk_en) aclk_div <= aclk_div+3'h1; // Generate SMCLK //---------------------------- reg [2:0] smclk_div; wire smclk_in = ~scg1 & (bcsctl2[`SELS] ? lfxt_clk_en : 1'b1); wire smclk_en = smclk_in & ((bcsctl2[`DIVSx]==2'b00) ? 1'b1 : (bcsctl2[`DIVSx]==2'b01) ? smclk_div[0] : (bcsctl2[`DIVSx]==2'b10) ? &smclk_div[1:0] : &smclk_div[2:0]); always @ (posedge mclk or posedge puc) if (puc) smclk_div <= 3'h0; else if ((bcsctl2[`DIVSx]!=2'b00) & smclk_in) smclk_div <= smclk_div+3'h1; //============================================================================= // 6) RESET GENERATION //============================================================================= // Generate synchronized POR wire por_reset = !reset_n; reg [1:0] por_s; always @(posedge mclk_n or posedge por_reset) if (por_reset) por_s <= 2'b11; else por_s <= {por_s[0], 1'b0}; wire por = por_s[1]; // Generate main system reset wire puc_reset = por_reset | wdt_reset | dbg_reset; reg [1:0] puc_s; always @(posedge mclk_n or posedge puc_reset) if (puc_reset) puc_s <= 2'b11; else puc_s <= {puc_s[0], 1'b0}; wire puc = puc_s[1]; endmodule // omsp_clock_module `include "openMSP430_undefines.v"