Add support for external triggers.

Author: inductivekickback

main.py

@@ -58,8 +58,19 @@ def _measure_avg(ppk_api, time_s, out_file):
 
 
 def _measure_triggers(ppk_api, time_us, level_ua, count, out_file):
-    """Prints the average current after the trigger voltage is reached."""
+    """Acquire and process trigger buffers."""
     buffers = ppk_api.measure_triggers(time_us, level_ua, count)
+    _process_triggers(buffers, out_file)
+
+
+def _measure_ext_triggers(ppk_api, time_us, count, out_file):
+    """Acquire and process external trigger buffers."""
+    buffers = ppk_api.measure_external_triggers(time_us, count)
+    _process_triggers(buffers, out_file)
+
+
+def _process_triggers(buffers, out_file):
+    """Save the buffers if necessary and print their averages."""
     if out_file:
         with open(out_file, "w", newline='') as csv_file:
             csv_writer = csv.writer(csv_file)
@@ -99,8 +110,6 @@ def _add_and_parse_args():
                         help="serial number of J-Link")
     parser.add_argument("-a", "--average", type=float,
                         help="print average current over time")
-    parser.add_argument("-t", "--trigger_microamps", type=int,
-                        help="set trigger threshold in microamps")
     parser.add_argument("-w", "--trigger_microseconds", type=int, nargs='?', default=5850,
                         help="set trigger window in microseconds")
     parser.add_argument("-n", "--trigger_count", type=int, nargs='?', default=1,
@@ -117,25 +126,29 @@ def _add_and_parse_args():
                         help="write measurement data to file", type=str)
     parser.add_argument("-g", "--spike_filtering",
                         help="enable spike filtering", action="store_true")
-    parser.add_argument("-x", "--enable_ext_trigger",
-                        help="enable 'TRIG IN' external trigger", action="store_true")
-    group = parser.add_mutually_exclusive_group()
-    group.add_argument("-k", "--skip_verify",
-                       help="save time by not verifying the PPK firmware",
-                       action="store_true")
-    group.add_argument("-f", "--force",
-                       help="program the PPK firmware if necessary",
-                       action="store_true")
+    trig_group = parser.add_mutually_exclusive_group()
+    trig_group.add_argument("-t", "--trigger_microamps", type=int,
+                            help="set trigger threshold in microamps")
+    trig_group.add_argument("-x", "--enable_ext_trigger",
+                            help="enable 'TRIG IN' external trigger", action="store_true")
+    fw_group = parser.add_mutually_exclusive_group()
+    fw_group.add_argument("-k", "--skip_verify",
+                          help="save time by not verifying the PPK firmware",
+                          action="store_true")
+    fw_group.add_argument("-f", "--force",
+                          help="program the PPK firmware if necessary",
+                          action="store_true")
     return (parser, parser.parse_args())
 
 
 def _main():
     """Parses arguments for the PPK CLI."""
     parser, args = _add_and_parse_args()
 
-    if not args.trigger_microamps:
-        if not args.average or args.enable_ext_trigger:
+    if not args.trigger_microamps and not args.enable_ext_trigger:
+        if not args.average:
             parser.print_usage()
+            print("main.py: error: no measurement operation specified")
             sys.exit(-1)
 
     nrfjprog_api = None
@@ -147,7 +160,8 @@ def _main():
 
         if args.external_vdd:
             if args.external_vdd < ppk_api.VDD_SET_MIN or args.external_vdd > ppk_api.VDD_SET_MAX:
-                print("Invalid external voltage regulator value (%d)." % args.external_vdd)
+                parser.print_usage()
+                print("main.py: error: invalid external voltage regulator value (%d)" % args.external_vdd)
                 _close_and_exit(nrfjprog_api, -1)
             else:
                 ppk_api.vdd_set(args.external_vdd)
@@ -166,9 +180,6 @@ def _main():
         if args.spike_filtering:
             ppk_api.enable_spike_filtering()
 
-        if args.enable_ext_trigger:
-            ppk_api.enable_ext_trigger_in()
-
         if args.average:
             _measure_avg(ppk_api, args.average, args.out_file)
 
@@ -178,10 +189,15 @@ def _main():
                               args.trigger_microamps,
                               args.trigger_count,
                               args.out_file)
+        elif args.enable_ext_trigger:
+            _measure_ext_triggers(ppk_api,
+                                  args.trigger_microseconds,
+                                  args.trigger_count,
+                                  args.out_file)
 
         _close_and_exit(nrfjprog_api, 0)
     except Exception as ex:
-        print(ex)
+        print("main.py: error: " + str(ex))
         _close_and_exit(nrfjprog_api, -1)
 
 

ppk/ppk.py

@@ -21,7 +21,7 @@ def __init__(self, error=None):
 
 class RTTCommand():
     """RTT command opcodes."""
-    TRIGGER_SET = 0x01
+    TRIG_SET = 0x01
     TRIG_WINDOW_SET = 0x03
     TRIG_SINGLE_SET = 0x05
     AVERAGE_START = 0x06
@@ -109,24 +109,6 @@ def get_metadata(self):
             raise PPKError("Invalid operation: must connect first.")
         return self._metadata.copy()
 
-    def enable_ext_trigger_in(self):
-        """Enable the 'TRIG IN' external trigger."""
-        if not self._connected:
-            raise PPKError("Invalid operation: must connect first.")
-        self._log("Enable 'TRIG IN' external trigger.")
-        if not self._ext_trig_enabled:
-            self._write_ppk_cmd([RTTCommand.EXT_TRIG_IN_TOGGLE])
-            self._ext_trig_enabled = True
-
-    def disable_ext_trigger_in(self):
-        """Disable the 'TRIG IN' external trigger."""
-        if not self._connected:
-            raise PPKError("Invalid operation: must connect first.")
-        self._log("Disable 'TRIG IN' external trigger.")
-        if self._ext_trig_enabled:
-            self._write_ppk_cmd([RTTCommand.EXT_TRIG_IN_TOGGLE])
-            self._ext_trig_enabled = False
-
     def enable_dut_power(self):
         """Turn DUT power on."""
         if not self._connected:
@@ -166,7 +148,13 @@ def set_user_resistors(self, user_r1, user_r2, user_r3):
         self._write_ppk_cmd(cmd)
 
     def enable_spike_filtering(self):
-        """Enable spike filtering feature."""
+        """Enable spike filtering feature.
+
+        When this is turned on, the PPK software will filter data directly
+        after an automatic range switch. This will limit unwanted spikes
+        due to rapid switching, but may also remove short current spikes
+        that might be of significance.
+        """
         if not self._connected:
             raise PPKError("Invalid operation: must connect first.")
         self._log("Enabling spike filtering.")
@@ -253,13 +241,25 @@ def measure_triggers(self, window_time_us, level_ua, count=1):
         if not self._connected:
             raise PPKError("Invalid operation: must connect first.")
         self._log("measure_triggers(%r, %r, %r)." % (window_time_us, level_ua, count))
-        ppk_helper = PPKDataHelper()
         self.set_trigger_window(window_time_us)
         if count == 1:
             self._set_single_trigger(level_ua)
         else:
             self._set_trigger(level_ua)
-        # Each buffer includes a timestamp.
+        return self._measure_triggers(count)
+
+    def measure_external_triggers(self, window_time_us, count=1):
+        """Wait for the 'TRIG IN' pin before capturing trigger buffers."""
+        if not self._connected:
+            raise PPKError("Invalid operation: must connect first.")
+        self._log("measure_external_triggers(%r, %r)." % (window_time_us, count))
+        self.set_trigger_window(window_time_us)
+        self._enable_ext_trigger_in()
+        return self._measure_triggers(count)
+
+    def _measure_triggers(self, count=1):
+        """"""
+        ppk_helper = PPKDataHelper()
         samples_count = count * 2
         while True:
             self._read_and_parse_ppk_data(ppk_helper)
@@ -268,7 +268,10 @@ def measure_triggers(self, window_time_us, level_ua, count=1):
             if samples_count <= collected_buffs:
                 break
         self._log('')
-        self._stop_trigger()
+        if self._ext_trig_enabled:
+            self._disable_ext_trigger_in()
+        else:
+            self._stop_trigger()
         self._flush_rtt()
         result = []
         for ts, trig_buf in ppk_helper.get_trigger_buffs(*self._resistors):
@@ -277,6 +280,24 @@ def measure_triggers(self, window_time_us, level_ua, count=1):
             result.append((np_avg(trig_buf), timestamped_buf))
         return result
 
+    def _enable_ext_trigger_in(self):
+        """Enable the 'TRIG IN' external trigger.
+
+        The external trigger is used in place of the normal TRIG_SET
+        and TRIG_SINGLE_SET commands.
+        """
+        self._log("Enable 'TRIG IN' external trigger.")
+        if not self._ext_trig_enabled:
+            self._write_ppk_cmd([RTTCommand.EXT_TRIG_IN_TOGGLE])
+            self._ext_trig_enabled = True
+
+    def _disable_ext_trigger_in(self):
+        """Disable the 'TRIG IN' external trigger."""
+        self._log("Disable 'TRIG IN' external trigger.")
+        if self._ext_trig_enabled:
+            self._write_ppk_cmd([RTTCommand.EXT_TRIG_IN_TOGGLE])
+            self._ext_trig_enabled = False
+
     def _start_average_measurement(self):
         """Start generating average current measurements."""
         self._log("Starting average measurement.")
@@ -298,7 +319,7 @@ def _set_trigger(self, level_ua):
         high = (level_ua >> 16) & 0xFF
         mid = (level_ua >> 8) & 0xFF
         low = level_ua & 0xFF
-        self._write_ppk_cmd([RTTCommand.TRIGGER_SET, high, mid, low])
+        self._write_ppk_cmd([RTTCommand.TRIG_SET, high, mid, low])
 
     def _set_single_trigger(self, level_ua):
         """Set the single trigger level.