LoPy4 not always getting heartbeat (blue LED)

[christian_kohler]

Hi, I'm running a LoPy4 on the Pycom Expansion Board. I don't have anything in boot.py, my main.py is connecting to a WiFi AP, writing to the SD card, reading a couple of i2c sensors and posting results using the urequests library. I loaded the code using the Atom PyMakr 1.2.9 plugin over the USB connection to my Macbook Pro.

This system was working fine, but after a few time disconnecting the board, I've noticed that sometimes it does not fully power-up. The green LED briefly comes on, but sometimes the blue flashing heartbeat does not start. I'm unable to connect to REPL over USB. I'm powering it from USB on my Macbook Pro (USB-C to USB converter). About half the time it works (ie gets to blue flashing heartbeat) and the other times it doesn't work. In the cases where it doesn't work I can press the reset button on the board, and it starts working. But I need this board to work unattended after a power-cycling event.

(sysname='LoPy4', nodename='LoPy4', release='1.17.0.b1', version='v1.8.6-849-d0dc708 on 2018-02-27', machine='LoPy4 with ESP32', lorawan='1.0.2', sigfox='1.0.1')

Any suggestions on how to make this more reliable?

Thanks

Christian

[seb]

I have only seen this be an issue when using FiPy/GPy with Pysense/Pytrack boards but t could be that the module is not getting enough power and cannot boot properly. Could you try the following:

• Make sure all the jumpers are properly seated on the expansion board
• A different, good quality USB cable that can handle a large current draw
• A different, good quality USB-C adapter that can handle a large current draw
• A different USB port on your macbook

I have also seen a user report adding a battery to the battery connector helped provide the extra power during the initial current in-rush but you shouldn't have to do this with a LoPy4.

[christian_kohler]

@seb OK, I think you are right that it is a power supply issue. I've tried the same cable directly with a USB power supply and haven't seen the issue happen again. So it might be for some reason that the Macbook USB port (or adapter) cannot supply enough power. Will try it with a LiPo connected.