Undervoltage and throtteling of Pi
A frequent problem with Raspberry Pi is undervoltage and overheating. This can cause severe problems during operation:
- Reduction of CPU frequency
- Software crashes
- Disconnecting USB devices
- Reboot of the Raspberry Pi
- Unstable Wifi
- Camera problems
How to detect that I have this problem
We highly recommend to use Repetier-Server 0.94 or newer, because there we have added a test for these problems. In the menu bar you see a bolt icon that shows hardware infos when opened. When your Pi detected undervoltage or was throttled due to overheating or undervoltage, you will see an entry about this. Note that at the beginning there might be no entry and it appears during operation when CPU gets hot or the load changes.
Alternatively you can login using SSH and run:
If it returns 0x0 everything is ok.
If the problem is overheating, you should improve cooling, so that the air can circulate.
If the problem is undervoltage, the voltage should be stabilized on a higher level. There are several ways to do this:
- Use a good power supply and not a cheap phone charger, because they do not react quickly to voltage changes. Use a solid 3A power supply, best with 5.1 V output.
- Use a good USB cable from the power supply to the Pi. Some cables have a higher internal resistance so that not enough voltage reaches the Pi.
- Do not connect too many devices that draw voltage. Use an active USB hub instead.
- Some printers use power from the Pi to supply power to the printer’s motherboard and display, although they could also be supplied directly from the printer’s internal power supply. In this case you can tape over the VBUS (+5 V) on pin 1 with electrical tape:
Pin 1: VBUS (+5 V)
Pin 2: Data-
Pin 3: Data+
Pin 4: Ground
With flat tweezers this is quickly covered:
If you cover the wrong pin, communication might not work. In this case just remove the plug und place the tape on the correct pin.
A few printers only work with 5V over USB. For these the fix will not work, so that you have to remove the tape.