TImer working with tests

TODO: think of other way of shifting in data. Bit errors make uploading difficult

rtl/core/mcu.v

@@ -88,7 +88,7 @@ module mcu #(
     ) servile (
         .i_clk(i_clk),
         .i_rst(rst),
-        .i_timer_irq(1'b0), //timer_irq),
+        .i_timer_irq(timer_irq),
 
         //Memory interface
         .o_wb_mem_adr(wb_mem_adr),

rtl/toplevel/top_generic.v

@@ -23,6 +23,26 @@ module top_generic #(
         .clk_out_15(clk_15)
     );
 
+    // Reset conditioning for button input:
+    // - asynchronous assert when button is pressed (aresetn=0)
+    // - synchronous, debounced deassert in clk_15 domain
+    localparam [17:0] RESET_RELEASE_CYCLES = sim ? 18'd16 : 18'd150000; // ~10 ms @ 15 MHz on hardware
+    reg [17:0] rst_cnt = 18'd0;
+    reg        sys_reset_r = 1'b1;
+    always @(posedge clk_15 or negedge aresetn) begin
+        if (!aresetn) begin
+            rst_cnt <= 18'd0;
+            sys_reset_r <= 1'b1;
+        end else if (sys_reset_r) begin
+            if (rst_cnt == RESET_RELEASE_CYCLES - 1'b1)
+                sys_reset_r <= 1'b0;
+            else
+                rst_cnt <= rst_cnt + 1'b1;
+        end
+    end
+    wire sys_reset = sys_reset_r;
+    wire sys_resetn = !sys_reset_r;
+
     wire [31:0] GPIO_A;
     wire [31:0] GPIO_B;
     wire [31:0] GPIO_C;
@@ -35,7 +55,7 @@ module top_generic #(
         .sim(sim)
     ) mcu (
         .i_clk(clk_15),
-        .i_rst(!aresetn),
+        .i_rst(sys_reset),
         .i_GPI_A(GPIO_A),
         .i_GPI_B(GPIO_B),
         .i_GPI_C(GPIO_C),
@@ -55,7 +75,7 @@ module top_generic #(
         .FS_HZ(80_000)
     ) nco (
         .clk    (clk_15),
-        .rst_n  (aresetn),
+        .rst_n  (sys_resetn),
         .freq_hz(GPIO_A),
         .sin_q15(sin_q15),
         .cos_q15(),

rtl/wb/jtag_wb_bridge.v

@@ -107,7 +107,7 @@ module jtag_wb_bridge #(
     reg [31:0] wb_dat_r;
     reg [3:0] wb_sel_r;
     reg wb_we_r;
-    reg cmd_reset_pulse_r;
+    reg cmd_reset_level_r;
     reg [31:0] resp_addr_r;
     reg [7:0] resp_data_r;
 
@@ -133,7 +133,7 @@ module jtag_wb_bridge #(
     assign o_wb_we = wb_we_r;
     assign o_wb_cyc = wb_busy;
     assign o_wb_stb = wb_busy;
-    assign o_cmd_reset = cmd_reset_pulse_r;
+    assign o_cmd_reset = cmd_reset_level_r;
 
     always @(posedge i_clk) begin
         if (i_rst) begin
@@ -148,7 +148,7 @@ module jtag_wb_bridge #(
             wb_dat_r <= 32'b0;
             wb_sel_r <= 4'b0000;
             wb_we_r <= 1'b0;
-            cmd_reset_pulse_r <= 1'b0;
+            cmd_reset_level_r <= 1'b0;
             resp_addr_r <= 32'b0;
             resp_data_r <= 8'b0;
         end else begin
@@ -157,12 +157,11 @@ module jtag_wb_bridge #(
             s_req_sync_3 <= s_req_sync_2;
             s_cmd_sync_1 <= j_cmd_hold;
             s_cmd_sync_2 <= s_cmd_sync_1;
-            cmd_reset_pulse_r <= 1'b0;
-
             if (req_pulse && !wb_busy) begin
                 wb_busy <= 1'b1;
                 wb_we_r <= cmd_we;
                 wb_adr_r <= cmd_addr;
+                cmd_reset_level_r <= cmd_reset;
 
                 case (req_lane)
                     2'b00: begin wb_sel_r <= 4'b0001; wb_dat_r <= {24'b0, cmd_wdata}; end
@@ -170,8 +169,6 @@ module jtag_wb_bridge #(
                     2'b10: begin wb_sel_r <= 4'b0100; wb_dat_r <= {8'b0, cmd_wdata, 16'b0}; end
                     default: begin wb_sel_r <= 4'b1000; wb_dat_r <= {cmd_wdata, 24'b0}; end
                 endcase
-
-                cmd_reset_pulse_r <= cmd_reset;
             end
 
             if (wb_busy && i_wb_ack) begin

sim/tb/tb_top_generic.v

@@ -11,7 +11,7 @@ module tb_top_generic();
 
     // 100 MHz board input clock
     initial aclk = 1'b0;
-    always #5 aclk = ~aclk;
+    always #33.33 aclk = ~aclk;
 
     // Hold reset low, then release
     initial begin
@@ -39,7 +39,7 @@ module tb_top_generic();
         $dumpvars(0, tb_top_generic);
 
         // Let firmware run for a while.
-        #5_000_000;
+        #2_000_000;
         $finish;
     end
 endmodule

sw/sweep/link.ld

@@ -24,6 +24,8 @@ SECTIONS
   {
     __bss_start = .;
     *(.bss .bss.*)
+    *(.sbss .sbss.*)
+    *(.scommon)
     *(COMMON)
     __bss_end = .;
   } > RAM

sw/sweep/start.s

@@ -1,7 +1,6 @@
 .section .text.init
 .globl _start
 .type _start, @function
-
 _start:
     la sp, __stack_top
 
@@ -21,3 +20,80 @@ _start:
     j 3b
 
 .size _start, .-_start
+
+
+.section .text
+.globl trap_entry
+.type trap_entry, @function
+trap_entry:
+    # Save full integer context (except x0/x2) because an interrupt can
+    # preempt code with live values in any register, not just caller-saved.
+    addi sp, sp, -128
+    sw   ra, 124(sp)
+    sw   gp, 120(sp)
+    sw   tp, 116(sp)
+    sw   t0, 112(sp)
+    sw   t1, 108(sp)
+    sw   t2, 104(sp)
+    sw   s0, 100(sp)
+    sw   s1,  96(sp)
+    sw   a0,  92(sp)
+    sw   a1,  88(sp)
+    sw   a2,  84(sp)
+    sw   a3,  80(sp)
+    sw   a4,  76(sp)
+    sw   a5,  72(sp)
+    sw   a6,  68(sp)
+    sw   a7,  64(sp)
+    sw   s2,  60(sp)
+    sw   s3,  56(sp)
+    sw   s4,  52(sp)
+    sw   s5,  48(sp)
+    sw   s6,  44(sp)
+    sw   s7,  40(sp)
+    sw   s8,  36(sp)
+    sw   s9,  32(sp)
+    sw   s10, 28(sp)
+    sw   s11, 24(sp)
+    sw   t3,  20(sp)
+    sw   t4,  16(sp)
+    sw   t5,  12(sp)
+    sw   t6,   8(sp)
+
+    csrr t0, mcause
+    li   t1, 0x80000007      # machine timer interrupt (RV32)
+    bne  t0, t1, 1f
+    call timer_isr           # C function that ACKs/clears the timer so i_timer_irq goes low
+1:
+    lw   t6,   8(sp)
+    lw   t5,  12(sp)
+    lw   t4,  16(sp)
+    lw   t3,  20(sp)
+    lw   s11, 24(sp)
+    lw   s10, 28(sp)
+    lw   s9,  32(sp)
+    lw   s8,  36(sp)
+    lw   s7,  40(sp)
+    lw   s6,  44(sp)
+    lw   s5,  48(sp)
+    lw   s4,  52(sp)
+    lw   s3,  56(sp)
+    lw   s2,  60(sp)
+    lw   a7,  64(sp)
+    lw   a6,  68(sp)
+    lw   a5,  72(sp)
+    lw   a4,  76(sp)
+    lw   a3,  80(sp)
+    lw   a2,  84(sp)
+    lw   a1,  88(sp)
+    lw   a0,  92(sp)
+    lw   s1,  96(sp)
+    lw   s0, 100(sp)
+    lw   t2, 104(sp)
+    lw   t1, 108(sp)
+    lw   t0, 112(sp)
+    lw   tp, 116(sp)
+    lw   gp, 120(sp)
+    lw   ra, 124(sp)
+    addi sp, sp, 128
+    mret

sw/sweep/sweep.c

@@ -1,14 +1,45 @@
 #include <stdint.h>
 
 #define GPIO_BASE   0x40000000u
+static volatile uint32_t * const R_FREQ     = (volatile uint32_t *)(GPIO_BASE+0);
+static volatile uint32_t * const LEDS       = (volatile uint32_t *)(GPIO_BASE+4);
+static volatile uint32_t * const LEDGR      = (volatile uint32_t *)(GPIO_BASE+8);
 
-static volatile uint32_t * const R_FREQ = (volatile uint32_t *)GPIO_BASE;
+#define TIMER_BASE  0x40010000u
+static volatile uint32_t * const TIMER      = (volatile uint32_t *)(TIMER_BASE+0);
+
+#define MSTATUS_MIE (1u << 3)
+#define MIE_MTIE    (1u << 7)
+
+extern void trap_entry();
+
+static inline void irq_init() {
+    /* mtvec first */
+    asm volatile ("csrw mtvec, %0" :: "r"(trap_entry));
+
+    /* enable machine timer interrupt */
+    asm volatile ("csrs mie, %0" :: "r"(MIE_MTIE));
+
+    /* global enable last */
+    asm volatile ("csrs mstatus, %0" :: "r"(MSTATUS_MIE));
+}
+
+void timer_isr(){
+    static int set = 0;
+    *TIMER = 18400;
+    *LEDGR = ~(*LEDGR);
+}
 
 void main(){
+    irq_init();
+
+    *LEDGR = 3;
+    *TIMER = 18400;
+
     for(;;){
         for(int i=1000; i<10000; i++){
             *R_FREQ = i;
-            // for(int j=0; j<100; j++) asm volatile("nop");
+            for(int j=0; j<100; j++) asm volatile("nop");
         }
     }
 }