Made abort procedure more robust

Instead of relying on Pi Pico GPIO beating external drives (not guaranteed with optoisolators!), just override PIO to send push instruction.
Clear PIO memory during PIO init so that it does not run out if there are many aborts.

dds-sweeper/dds-sweeper.c

@@ -102,12 +102,14 @@ void init_pin(uint pin) {
 }
 
 void init_pio() {
+    pio_clear_instruction_memory(PIO_TRIG);
     uint offset = pio_add_program(PIO_TRIG, &trigger_program);
     uint trigger = timing ? INT_TRIGGER : TRIGGER;
     uint profile_low = PROFILE_ASC ? P0 : P3;
     trigger_program_init(PIO_TRIG, 0, offset, trigger, profile_low, PIN_UPDATE);
 
     if(timing) {
+        pio_clear_instruction_memory(PIO_TIME);
         offset = pio_add_program(PIO_TIME, &timer_program);
         timer_program_init(PIO_TIME, 0, offset, TRIGGER, INT_TRIGGER);
     }
@@ -182,21 +184,10 @@ void abort_run() {
     if (get_status() == RUNNING) {
         set_status(ABORTING);
 
-        // take control of trigger pin from PIO
-        if(timing) {
-            init_pin(INT_TRIGGER);
-            gpio_put(INT_TRIGGER, 1);
-            sleep_ms(1);
-            gpio_put(INT_TRIGGER, 0);
-        }
-        else {
-            init_pin(TRIGGER);
-            gpio_put(TRIGGER, 1);
-            sleep_ms(1);
-            gpio_put(TRIGGER, 0);
-        }
+        // Make trigger PIO trigger immediately so background aborts
+        pio_sm_exec(PIO_TRIG, 0, pio_encode_push(false, false));
 
-        // reinit PIO to give Trigger pin back
+        // reinit PIO
         init_pio();
     }
 }