Why is my Raspberry Pi and Notecard resetting when the Notecard modem is on

Troubleshooting
1
Summary

Raspberry Pi restarts when Notecard modem is on.

Resolution

Use Raspberry Pi 4 or provide supplemental power to the Notecarrier-Pi Hat.

Raspberry Pi Restarting

When I issue a command to the Notecard, the Raspberry Pi restarts, and also causes the Notecard to restart.

Hardware Configurations

  • Raspberry Pi 3B+
  • Notecard (any variant)

Raspberry Pi / Notecard Connection Configurations:

  1. Notecard mounted to a Notecarrier-Pi Hat that is mounted to the Raspberry Pi headers
  2. Notecard mounted in any Notecarrier, connected to the Raspberry Pi via USB port

Approximate Reproduction Steps:

  1. Ensure the Notecard modem is on.
    This can be done by enabling hub continuous connection mode on the Notecard
{"req":"hub.set","mode":"continuous"}

This forces the modem to be on continuously.

Aside

The Notecard modem is on if the GREEN LED on the Notecard is on
More about Notecard LED

  1. Issue some additional command to Raspberry Pi peripheral that causes additional current draw
    We have seen this when opening the I2C port or serial port on the Raspberry Pi to the Notecard.

Precise reproduction steps are difficult to determine. The issue is the total current drawn by the Raspberry Pi, Notecard, and any other devices that might be connected to the Raspberry Pi and drawing current.

Resolution Options:

1. Apply supplemental power to Notecard over USB

If hardware configuration is using the Notecarrier-Pi Hat mounted to the Raspberry Pi header, then plug in a USB power supply to the Notecarrier-Pi Hat micro USB port.

In this configuration, the micro USB port on the Notecarrier-Pi Hat only supplies additional power to the Notecard. A diode network prevents the sharing of power with the Raspberry Pi or other Pi-hats.

2. Use a Raspberry Pi 4

The Raspberry Pi 3B+ has a current limiting resettable fuse on the 5 volt supply trace. The modem on the Notecard is connected to this trace via the Raspberry Pi header.

If the total current draw on this power supply from the Notecard, Raspberry Pi operation, and other power consuming peripherals exceeds much more than 2.5 amps, then the fuse trips, and causes power to be cut to the Raspberry Pi and child components.

The Raspberry Pi 4 board no longer contains that fuse on the 5 voltage supply trace.

Important
Early versions of the Raspberry Pi 4 hardware seemed to have some other issues. Double check you are using a relatively recent hardware version.

To get hardware version information, use the following on the Raspberry Pi terminal:


sudo /opt/vc/bin/vcgencmd version

Example Response:


Sep 2, 2020
Copyright (c) 2012 Broadcom
version 4439d2aaa6c376a2d1ef4402f142e1cf4de37c43 (clean) (release) (start)
2

Adding my 2 cents… if you are relatively new to Raspberry, a quality power supply is essential.

For a Pi3B+

  • Standard USB power supplies like Apple charger only supply 2.4A. You really want 2.5A, it makes a difference.
  • Standard USB power supplies use a plug-in USB cord. Lot of them use an wire gauge that is too small and drop voltage. Check Amazon and others for quality cords.
    –> Recommendation: purchase a 3A microUSB like this. Twice the cost of the genuine Raspberry model – the only other option in IMO.

For a Pi4
So for we’ve only used genuine Raspberry power supplies without a glitch.