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[/] [rtcclock/] [trunk/] [rtl/] [rtclight.v] - Rev 8
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/////////////////////////////////////////////////////////////////////////// // // Filename: rtclight.v // // Project: A Wishbone Controlled Real--time Clock Core // // Purpose: Implement a real time clock, including alarm, count--down // timer, stopwatch, variable time frequency, and more. // // This is a light-weight version of the RTC found in this directory. // Unlike the full RTC, this version does not support time hacks, seven // segment display outputs, or LED's. It is an RTC for an internal core // only. (That's how I was using it on one of my projects anyway ...) // // // Creator: Dan Gisselquist, Ph.D. // Gisselquist Technology, LLC // /////////////////////////////////////////////////////////////////////////// // // Copyright (C) 2015, Gisselquist Technology, LLC // // This program is free software (firmware): you can redistribute it and/or // modify it under the terms of the GNU General Public License as published // by the Free Software Foundation, either version 3 of the License, or (at // your option) any later version. // // This program is distributed in the hope that it will be useful, but WITHOUT // ANY WARRANTY; without even the implied warranty of MERCHANTIBILITY or // FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License // for more details. // // You should have received a copy of the GNU General Public License along // with this program. (It's in the $(ROOT)/doc directory. Run make with no // target there if the PDF file isn't present.) If not, see // <http://www.gnu.org/licenses/> for a copy. // // License: GPL, v3, as defined and found on www.gnu.org, // http://www.gnu.org/licenses/gpl.html // // /////////////////////////////////////////////////////////////////////////// module rtclight(i_clk, // Wishbone interface i_wb_cyc, i_wb_stb, i_wb_we, i_wb_addr, i_wb_data, // o_wb_ack, o_wb_stb, o_wb_data, // no reads here // // Button inputs // i_btn, // Output registers o_data, // multiplexed based upon i_wb_addr // Output controls o_interrupt, // A once-per-day strobe on the last clock of the day o_ppd); parameter DEFAULT_SPEED = 32'd2814750; // 100 Mhz input i_clk; input i_wb_cyc, i_wb_stb, i_wb_we; input [2:0] i_wb_addr; input [31:0] i_wb_data; // input i_btn; output reg [31:0] o_data; output wire o_interrupt, o_ppd; reg [21:0] clock; reg [31:0] stopwatch, ckspeed; reg [25:0] timer; wire ck_sel, tm_sel, sw_sel, sp_sel, al_sel; assign ck_sel = ((i_wb_cyc)&&(i_wb_stb)&&(i_wb_addr[2:0]==3'b000)); assign tm_sel = ((i_wb_cyc)&&(i_wb_stb)&&(i_wb_addr[2:0]==3'b001)); assign sw_sel = ((i_wb_cyc)&&(i_wb_stb)&&(i_wb_addr[2:0]==3'b010)); assign al_sel = ((i_wb_cyc)&&(i_wb_stb)&&(i_wb_addr[2:0]==3'b011)); assign sp_sel = ((i_wb_cyc)&&(i_wb_stb)&&(i_wb_addr[2:0]==3'b100)); reg [39:0] ck_counter; reg ck_carry; always @(posedge i_clk) { ck_carry, ck_counter } <= ck_counter + { 8'h00, ckspeed }; wire ck_pps; reg ck_prepps, ck_ppm, ck_pph, ck_ppd; reg [7:0] ck_sub; initial clock = 22'h00000; assign ck_pps = (ck_carry)&&(ck_prepps); always @(posedge i_clk) begin if (ck_carry) ck_sub <= ck_sub + 8'h1; ck_prepps <= (ck_sub == 8'hff); if (ck_pps) begin // advance the seconds if (clock[3:0] >= 4'h9) clock[3:0] <= 4'h0; else clock[3:0] <= clock[3:0] + 4'h1; if (clock[7:0] >= 8'h59) clock[7:4] <= 4'h0; else if (clock[3:0] >= 4'h9) clock[7:4] <= clock[7:4] + 4'h1; end ck_ppm <= (clock[7:0] == 8'h59); if ((ck_pps)&&(ck_ppm)) begin // advance the minutes if (clock[11:8] >= 4'h9) clock[11:8] <= 4'h0; else clock[11:8] <= clock[11:8] + 4'h1; if (clock[15:8] >= 8'h59) clock[15:12] <= 4'h0; else if (clock[11:8] >= 4'h9) clock[15:12] <= clock[15:12] + 4'h1; end ck_pph <= (clock[15:0] == 16'h5959); if ((ck_pps)&&(ck_pph)) begin // advance the hours if (clock[21:16] >= 6'h23) begin clock[19:16] <= 4'h0; clock[21:20] <= 2'h0; end else if (clock[19:16] >= 4'h9) begin clock[19:16] <= 4'h0; clock[21:20] <= clock[21:20] + 2'h1; end else begin clock[19:16] <= clock[19:16] + 4'h1; end end ck_ppd <= (clock[21:0] == 22'h235959); if ((ck_sel)&&(i_wb_we)) begin if (8'hff != i_wb_data[7:0]) begin clock[7:0] <= i_wb_data[7:0]; ck_ppm <= (i_wb_data[7:0] == 8'h59); end if (8'hff != i_wb_data[15:8]) begin clock[15:8] <= i_wb_data[15:8]; ck_pph <= (i_wb_data[15:8] == 8'h59); end if (6'h3f != i_wb_data[21:16]) clock[21:16] <= i_wb_data[21:16]; if (8'h00 == i_wb_data[7:0]) ck_sub <= 8'h00; end end // Clock updates take several clocks, so let's make sure we // are only looking at a valid clock value before testing it. reg [21:0] ck_last_clock; always @(posedge i_clk) ck_last_clock <= clock[21:0]; reg tm_pps, tm_ppm, tm_int; wire tm_stopped, tm_running, tm_alarm; assign tm_stopped = ~timer[24]; assign tm_running = timer[24]; assign tm_alarm = timer[25]; reg [23:0] tm_start; reg [7:0] tm_sub; initial tm_start = 24'h00; initial timer = 26'h00; initial tm_int = 1'b0; initial tm_pps = 1'b0; always @(posedge i_clk) begin if (ck_carry) begin tm_sub <= tm_sub + 8'h1; tm_pps <= (tm_sub == 8'hff); end else tm_pps <= 1'b0; if ((~tm_alarm)&&(tm_running)&&(tm_pps)) begin // If we are running ... timer[25] <= 1'b0; if (timer[23:0] == 24'h00) timer[25] <= 1'b1; else if (timer[3:0] != 4'h0) timer[3:0] <= timer[3:0]-4'h1; else begin // last digit is a zero timer[3:0] <= 4'h9; if (timer[7:4] != 4'h0) timer[7:4] <= timer[7:4]-4'h1; else begin // last two digits are zero timer[7:4] <= 4'h5; if (timer[11:8] != 4'h0) timer[11:8] <= timer[11:8]-4'h1; else begin // last three digits are zero timer[11:8] <= 4'h9; if (timer[15:12] != 4'h0) timer[15:12] <= timer[15:12]-4'h1; else begin timer[15:12] <= 4'h5; if (timer[19:16] != 4'h0) timer[19:16] <= timer[19:16]-4'h1; else begin // timer[19:16] <= 4'h9; timer[23:20] <= timer[23:20]-4'h1; end end end end end end if((~tm_alarm)&&(tm_running)) begin timer[25] <= (timer[23:0] == 24'h00); tm_int <= (timer[23:0] == 24'h00); end else tm_int <= 1'b0; if (tm_alarm) timer[24] <= 1'b0; if ((tm_sel)&&(i_wb_we)&&(tm_running)) // Writes while running // Only allowed to stop the timer, nothing more timer[24] <= i_wb_data[24]; else if ((tm_sel)&&(i_wb_we)&&(tm_stopped)) // Writes while off begin timer[24] <= i_wb_data[24]; if ((timer[24])||(i_wb_data[24])) timer[25] <= 1'b0; if (i_wb_data[23:0] != 24'h0000) begin timer[23:0] <= i_wb_data[23:0]; tm_start <= i_wb_data[23:0]; tm_sub <= 8'h00; end else if (timer[23:0] == 24'h00) begin // Resetting timer to last valid timer start val timer[23:0] <= tm_start; tm_sub <= 8'h00; end // Any write clears the alarm timer[25] <= 1'b0; end end // // Stopwatch functionality // // Setting bit '0' starts the stop watch, clearing it stops it. // Writing to the register with bit '1' high will clear the stopwatch, // and return it to zero provided that the stopwatch is stopped either // before or after the write. Hence, writing a '2' to the device // will always stop and clear it, whereas writing a '3' to the device // will only clear it if it was already stopped. reg sw_pps, sw_ppm, sw_pph; reg [7:0] sw_sub; wire sw_running; assign sw_running = stopwatch[0]; initial stopwatch = 32'h00000; always @(posedge i_clk) begin sw_pps <= 1'b0; if (sw_running) begin if (ck_carry) begin sw_sub <= sw_sub + 8'h1; sw_pps <= (sw_sub == 8'hff); end end stopwatch[7:1] <= sw_sub[7:1]; if (sw_pps) begin // Second hand if (stopwatch[11:8] >= 4'h9) stopwatch[11:8] <= 4'h0; else stopwatch[11:8] <= stopwatch[11:8] + 4'h1; if (stopwatch[15:8] >= 8'h59) stopwatch[15:12] <= 4'h0; else if (stopwatch[11:8] >= 4'h9) stopwatch[15:12] <= stopwatch[15:12] + 4'h1; sw_ppm <= (stopwatch[15:8] == 8'h59); end else sw_ppm <= 1'b0; if (sw_ppm) begin // Minutes if (stopwatch[19:16] >= 4'h9) stopwatch[19:16] <= 4'h0; else stopwatch[19:16] <= stopwatch[19:16]+4'h1; if (stopwatch[23:16] >= 8'h59) stopwatch[23:20] <= 4'h0; else if (stopwatch[19:16] >= 4'h9) stopwatch[23:20] <= stopwatch[23:20]+4'h1; sw_pph <= (stopwatch[23:16] == 8'h59); end else sw_pph <= 1'b0; if (sw_pph) begin // And hours if (stopwatch[27:24] >= 4'h9) stopwatch[27:24] <= 4'h0; else stopwatch[27:24] <= stopwatch[27:24]+4'h1; if((stopwatch[27:24] >= 4'h9)&&(stopwatch[31:28] < 4'hf)) stopwatch[31:28] <= stopwatch[27:24]+4'h1; end if ((sw_sel)&&(i_wb_we)) begin stopwatch[0] <= i_wb_data[0]; if((i_wb_data[1])&&((~stopwatch[0])||(~i_wb_data[0]))) begin stopwatch[31:1] <= 31'h00; sw_sub <= 8'h00; sw_pps <= 1'b0; sw_ppm <= 1'b0; sw_pph <= 1'b0; end end end // // The alarm code // // Set the alarm register to the time you wish the board to "alarm". // The "alarm" will take place once per day at that time. At that // time, the RTC code will generate a clock interrupt, and the CPU/host // can come and see that the alarm tripped. // // reg [21:0] alarm_time; reg al_int, // The alarm interrupt line al_enabled, // Whether the alarm is enabled al_tripped; // Whether the alarm has tripped initial al_enabled= 1'b0; initial al_tripped= 1'b0; always @(posedge i_clk) begin if ((al_sel)&&(i_wb_we)) begin // Only adjust the alarm hours if the requested hours // are valid. This allows writes to the register, // without a prior read, to leave these configuration // bits alone. if (i_wb_data[21:16] != 6'h3f) alarm_time[21:16] <= i_wb_data[21:16]; // Here's the same thing for the minutes: only adjust // the alarm minutes if the new bits are not all 1's. if (i_wb_data[15:8] != 8'hff) alarm_time[15:8] <= i_wb_data[15:8]; // Here's the same thing for the seconds: only adjust // the alarm minutes if the new bits are not all 1's. if (i_wb_data[7:0] != 8'hff) alarm_time[7:0] <= i_wb_data[7:0]; al_enabled <= i_wb_data[24]; // Reset the alarm if a '1' is written to the tripped // register, or if the alarm is disabled. if ((i_wb_data[25])||(~i_wb_data[24])) al_tripped <= 1'b0; end al_int <= 1'b0; if ((ck_last_clock != alarm_time)&&(clock[21:0] == alarm_time) &&(al_enabled)) begin al_tripped <= 1'b1; al_int <= 1'b1; end end // // The ckspeed register is equal to 2^48 divded by the number of // clock ticks you expect per second. Adjust high for a slower // clock, lower for a faster clock. In this fashion, a single // real time clock RTL file can handle tracking the clock in any // device. Further, because this is only the lower 32 bits of a // 48 bit counter per seconds, the clock jitter is kept below // 1 part in 65 thousand. // initial ckspeed = DEFAULT_SPEED; // 2af31e = 2^48 / 100e6 MHz // In the case of verilator, comment the above and uncomment the line // below. The clock constant below is "close" to simulation time, // meaning that my verilator simulation is running about 300x slower // than board time. // initial ckspeed = 32'd786432000; always @(posedge i_clk) if ((sp_sel)&&(i_wb_we)) ckspeed <= i_wb_data; assign o_interrupt = tm_int || al_int; // A once-per day strobe, on the last second of the day so that the // the next clock is the first clock of the day. This is useful for // connecting this module to a year/month/date date/calendar module. assign o_ppd = (ck_ppd)&&(ck_pps); always @(posedge i_clk) case(i_wb_addr[2:0]) 3'b000: o_data <= { 10'h0, ck_last_clock }; 3'b001: o_data <= { 6'h00, timer }; 3'b010: o_data <= stopwatch; 3'b011: o_data <= { 6'h00, al_tripped, al_enabled, 2'b00, alarm_time }; 3'b100: o_data <= ckspeed; default: o_data <= 32'h000; endcase endmodule
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