if (init_done == 0 && sst == 0 )     // this is changed to prevent init of inverter during slow stop
     {
     init_vars();
     init_done = 1;
     }

 // scr shutdown - without a dummy connection of D6 to ground, inverter wont run.
 if (((PINB & 0x01) == 0) || ((PIND & 0x40) == 0x40))
 // for testing, do not check scr shutdown pin, just nano2 on/off
 //if (((PINB & 0x01) == 0) )  

void loop()
{
 float ch0;

 // sample channel..
 // In the past, I low pass filtered this. not now, no need thanks to active LP filter on Vfb
 ac_output = (float)analogRead(ADC_OUT) / 1024.0; // scale 0 - 5V to 0.0 to 1.0

 if(uf == 1 && (v1low == 1) )    // this will execute at 50Hz now
     {            // it runs at near zero volt crossing of AC output    

if (oen == 1)              // slow stop? I think of it as de-gauss
         {
         if(ac_output < ac_setpoint)
           pwr += 1.0/250.0;     // bang-bang control, should AC output reach setpoint prior to PID.
         else                    // During slow start need to ensure output is tracking setpoint
           {
             pwr -= 1.0/250.0;     // should output get close enough to matter.
           sst = 251;
           }
         }
       else
         pwr -= 1.0 /250.0;      // this will execute in slow stop
       }

..
void loop()
{
 float ch0;

 // sample channel..
 // In the past, I low pass filtered this. not now, no need thanks to active LP filter on Vfb
 ac_output = (float)analogRead(ADC_OUT) / 1024.0; // scale 0 - 5V to 0.0 to 1.0

 if(uf == 1  )    // this will execute at 100Hz
     {            // it runs at near zero volt crossing of AC output      
     uf=0;
     ac_setpoint = 0.55;       // for same Vfb as EG8010. change AC output voltage via Vfb voltage divider trimpot
     if (oen == 1) sst++;      // slow start. If output is enabled, keep starting up. sst = output pwm% or approx. voltage.
     if (sst > 251)sst = 251;  // stop increasing when sst has got to the end of slow start. when = 251, this enables PID. See below..
     if (oen == 0) sst--;      // if stopping, slow stop
     if (sst <= 0)             // once fully stopped, no more changes to sst needed
       {
       sst = 0;
       cbi(PORTD,5);     // pull IR2184 shutdown LOW to disable gate drive output
       }
     else
       sbi(PORTD,5);     // pull it HIGH, to enable output

     if(sst > 0 && sst < 250)     // slow start timer counts to 250 with gentle ramp up, then switches over to PID control. (gulp!)
       {                          // sst can increase or decrease, giving the slow start and slow stop.
       if (oen == 1)              // slow stop? I think of it as de-gauss
         {
         if(ac_output < ac_setpoint)
           pwr += 1.0/250.0;     // bang-bang control, should AC output reach setpoint prior to PID.
         else                    // During slow start need to ensure output is tracking setpoint
           pwr -= 1.0/250.0;     // should output get close enough to matter.
         }
       else
         pwr -= 1.0 /250.0;      // this will execute in slow stop
       }
       
     if (sst == 251)       // once sst = 251, run PID. the above bang-bang control will NOT have executed, because sst = 251
       {                  
       Setpoint = ac_setpoint;    
       Input = ac_output;  
       do_pid();
       pwr = pwr + Output;
       }
...