Verilog之openMSP430(1)

openMSP430_IO interrupt

Verilog file: omsp_gpio.v

 //============================================================================
 // 4) INTERRUPT GENERATION
 //============================================================================

 // Port 2 interrupt
 //------------------

 // Delay input // The p2in_dly stores former value of p2in, it will be used for edge detection
 reg    [:] p2in_dly;
 always @ (posedge mclk or posedge puc_rst)
   if (puc_rst)  p2in_dly <=  'h00;
   else          p2in_dly <=  p2in & P2_EN_MSK;    

 // Edge detection // Now we can detect rising and falling edge easily by combining p2in and p2in_dly
 wire   [:] p2in_re   =   p2in & ~p2in_dly;
 wire   [:] p2in_fe   =  ~p2in &  p2in_dly;

 // Set interrupt flag // p2ies register decide which edge is interrup signal; p2ifg_set is sent to p2ifg for interrupt flag
 assign       p2ifg_set = {p2ies[] ? p2in_fe[] : p2in_re[],
                           p2ies[] ? p2in_fe[] : p2in_re[],
                           p2ies[] ? p2in_fe[] : p2in_re[],
                           p2ies[] ? p2in_fe[] : p2in_re[],
                           p2ies[] ? p2in_fe[] : p2in_re[],
                           p2ies[] ? p2in_fe[] : p2in_re[],
                           p2ies[1] ? p2in_fe[] : p2in_re[],
                           p2ies[] ? p2in_fe[] : p2in_re[]} & P2_EN_MSK;

 // Generate CPU interrupt // Interrupt is generated when interrupt is enabled and p2ifg (interrupt flag) is available
 assign       irq_port2 = |(p2ie & p2ifg) & P2_EN[];

　　

　　Assume  P2_EN is 1'b1, interrupt is enabled(P2IE=1), interrupt edge is rising(P2IES=0), so the code is as following:

 // Delay input
 reg    [:] p2in_dly;
 always @ (posedge mclk or posedge puc_rst)
   if (puc_rst)  p2in_dly <=  'h00;
   else          p2in_dly <=  p2in;    

 // Edge detection
 wire   [:] p2in_re   =   p2in & ~p2in_dly;

 // Set interrupt flag
 assign       p2ifg_set = { p2in_re[],
                            p2in_re[],
                            p2in_re[],
                            p2in_re[],
                            p2in_re[],
                            p2in_re[],
                            p2in_re[],
                            p2in_re[]　　};

 // Generate CPU interrupt
 assign      irq_port2 = | p2ifg;

　　

　　P2IFG register is as following:

 // P2IFG Register
 //----------------
 reg  [:] p2ifg;

 wire       p2ifg_wr  = P2IFG[] ? reg_hi_wr[P2IFG] : reg_lo_wr[P2IFG];
 wire [:] p2ifg_nxt = P2IFG[] ? per_din[:]    : per_din[:];
 wire [:] p2ifg_set;

 always @ (posedge mclk or posedge puc_rst)
   if (puc_rst)        p2ifg <=  'h00;
   else if (p2ifg_wr)  p2ifg <=  (p2ifg_nxt | p2ifg_set) & P2_EN_MSK;
   else                p2ifg <=  (p2ifg     | p2ifg_set) & P2_EN_MSK;

　　Assume P2_EN is 1'b1; P2IFG='h2B, so P2IFG[0]=1;  p2ifg_set = 8{1'b1}

   // P2IFG Register
   //----------------
   reg  [:] p2ifg;

   wire       p2ifg_wr  =  reg_hi_wr[]; // If decoded address is P2IFG, then write it into data
   wire [:] p2ifg_nxt =  per_din[:]; // receive high byte data from openMSP
   wire [:] p2ifg_set;

   always @ (posedge mclk or posedge puc_rst)
    if (puc_rst)        p2ifg <=  'h00;
    else if (p2ifg_wr)  p2ifg <=  p2ifg_nxt | p2ifg_set; // write into
    else                p2ifg <=  p2ifg     | p2ifg_set; // read out