make PPK2 power supply monitor work in supply-mode

.vscode/launch.json

@@ -204,7 +204,7 @@
       "request": "launch",
       "module": "meshtastic",
       "justMyCode": false,
-      "args": ["--slog", "--power-ppk2-meter", "--power-stress", "--power-voltage", "3.3", "--seriallog", "--ble"]
+      "args": ["--slog", "--power-ppk2-supply", "--power-stress", "--power-voltage", "3.3", "--seriallog", "--ble"]
     },
     {
       "name": "meshtastic test",

meshtastic/__main__.py

@@ -1009,24 +1009,34 @@ def create_power_meter():
 
     global meter  # pylint: disable=global-statement
     args = mt_config.args
+
+    # If the user specified a voltage, make sure it is valid
+    v = 0.0
+    if args.power_voltage:
+        v = float(args.power_voltage)
+        if v < 0.8 or v > 5.0:
+            meshtastic.util.our_exit("Voltage must be between 0.8 and 5.0")
+
     if args.power_riden:
         meter = RidenPowerSupply(args.power_riden)
     elif args.power_ppk2_supply or args.power_ppk2_meter:
         meter = PPK2PowerSupply()
+        assert v > 0, "Voltage must be specified for PPK2"
+        meter.v = v  # PPK2 requires setting voltage before selecting supply mode
         meter.setIsSupply(args.power_ppk2_supply)
     elif args.power_sim:
         meter = SimPowerSupply()
 
-    if meter and args.power_voltage:
-        v = float(args.power_voltage)
-        if v < 0.5 or v >5.0:
-            meshtastic.util.our_exit("Voltage must be between 1.0 and 5.0")
+    if meter and v:
         logging.info(f"Setting power supply to {v} volts")
         meter.v = v
         meter.powerOn()
 
         if args.power_wait:
             input("Powered on, press enter to continue...")
+        else:
+            logging.info("Powered-on, waiting for device to boot")
+            time.sleep(5)
 
 def common():
     """Shared code for all of our command line wrappers."""

meshtastic/powermon/ppk2.py

@@ -118,9 +118,11 @@ class PPK2PowerSupply(PowerSupply):
         self.measurement_thread.join()  # wait for our thread to finish
         super().close()
 
-    def setIsSupply(self, s: bool):
+    def setIsSupply(self, is_supply: bool):
         """If in supply mode we will provide power ourself, otherwise we are just an amp meter."""
 
+        assert self.v > 0.8  # We must set a valid voltage before calling this method
+
         self.r.set_source_voltage(
             int(self.v * 1000)
         )  # set source voltage in mV BEFORE setting source mode
@@ -130,7 +132,7 @@ class PPK2PowerSupply(PowerSupply):
         self.r.start_measuring()  # send command to ppk2
 
         if (
-            not s
+            not is_supply
         ):  # min power outpuf of PPK2.  If less than this assume we want just meter mode.
             self.r.use_ampere_meter()
         else: