lowpower: warn about issue 5152 and WiFi.

Author: peterhinch

lowpower/README.md

@@ -85,10 +85,15 @@ that they are on `sys.path`.
  * `mqtt_log.py` A publish-only MQTT application for Pyboard D. See below.
 
 `mqtt_log.py` requires the `umqtt.simple`  library. This may be installed with
-[upip_m](https://github.com/peterhinch/micropython-samples/tree/master/micropip).
+upip. See [Installing library modules](https://github.com/peterhinch/micropython-samples/tree/master/micropip).
 ```
->>> upip_m.install('micropython-umqtt.simple')
+>>> import upip
+>>> upip.install('micropython-umqtt.simple')
 ```
+Owing to [this issue](https://github.com/micropython/micropython/issues/5152)
+this test is currently broken and I suspect that any usage of WiFi in low power
+mode will fail.
+
 This test is "experimental". Pyboard D support for low power WiFi is currently
 incomplete. I have seen anomolous results where power was low initially before
 jumping to ~30mA after a few hours. The application continued to run, but the

lowpower/mqtt_log.py

@@ -50,8 +50,10 @@ async def main(loop):
         Latency(2000)
         count = 0
         while True:
+            print('Publish')
             publish(ujson.dumps([count, rtc.datetime()]))
             count += 1
+            print('Wait 2 mins')
             await asyncio.sleep(120)  # 2 mins
     else:  # Fail to connect
         red.on()

lowpower/rtc_time.py

@@ -21,7 +21,7 @@
 # Power won't be saved if this is done.
 sleep_ms = utime.sleep_ms
 
-d_series = uname().machine[:5] == 'PYBD_'
+d_series = uname().machine[:4] == 'PYBD'
 use_utime = True  # Assume the normal utime timebase
 
 if sys.platform == 'pyboard':
@@ -41,6 +41,9 @@
 
 # For lowest power consumption set unused pins as inputs with pullups.
 # Note the 4K7 I2C pullups on X9 X10 Y9 Y10 (Pyboard 1.x).
+
+# Pulling Pyboard D pins should be disabled if using WiFi as it now seems to
+# interfere with it. Although until issue #5152 is fixed it's broken anyway.
 if d_series:
     print('Running on Pyboard D')
     if not use_utime: