Now this saves some startup time on the pips. We can actually shortern them with the time we've saved

In future potentially keep the si in standby mode rather than shutdown mode. This saves startup time, but could be a reliabilty issue as the si isn't getting a full hw reset each cycle. Probably don't bother, it doesn't matter that much

firmware/inc/pips.h

@@ -30,7 +30,7 @@
  */
 
 #define PIPS_RATE	1
-#define PIPS_LENGTH_MS	200
+#define PIPS_LENGTH_MS	125
 #define PIPS_FREQUENCY	(1000 / PIPS_LENGTH_MS)
 
 #endif /* PIPS_H */

firmware/src/si_trx.c

@@ -502,15 +502,15 @@ static void si_trx_set_frequency(struct si_frequency_configuration* config,
 void si_trx_reset(uint8_t modulation_type, struct si_frequency_configuration* fconfig,
                   uint16_t deviation, uint8_t power, enum si_filter_model filter)
 {
+  /* We expect to already be shutdown  */
   _si_trx_sdn_enable();  /* active high shutdown = reset */
 
-  for (int i = 0; i < 15*1000; i++); /* Approx. 15 */
-  _si_trx_sdn_disable();   /* booting */
-  for (int i = 0; i < 15*1000; i++); /* Approx. 15ms */
+  for (int i = 0; i < 15; i++); /* a few microseconds */
 
-  /* Check part number */
-  /* uint16_t part_number = si_trx_get_part_info(); */
-  /* while (part_number != 17512); */
+  _si_trx_sdn_disable();   /* booting. expected to take 15ms */
+
+  /* Poll for part number */
+  while (si_trx_get_part_info() != 17512);
 
   /* Power Up */
   si_trx_power_up(SI_POWER_UP_TCXO, VCXO_FREQUENCY);