Friday, November 3, 2017

Watch your cables

I was doing a project with a Raspberry Pi 3 when I encountered a strange problem.

I installed the Raspberry OS and wrote my software. next I tested it thoroughly until I was convinced everything worked as I planned. Next step was to move the Raspberry to its working location.

The location I planned for the raspberry had no wall power outlet. So I used a 5 meter long (16 foot) USB cable as a power source. Should be no problem as this cable powered a NodeMCU before.

But then the trouble started.

The Raspberry started as planned and then suddenly resetted. So I detached the power cable and re-attached it to reboot the Raspberry. That worked, however after a few seconds it resetted again.

I was sure I had a decent USB power supply attached: 5 Volts, 2.1 Amps. More as sufficient. And then I got an idea. I relocated the Raspberry and attached the original USB cable (1.8 meter) again. And everything worked as normal. So I replaced the 1.8 meter USB cable with the 5 meter cable and the problems started again: fault located !!!
The cable obviously had to much resistance which reduced the power.

I had used this cable with a NodeMCU before but obviously that draws less power as A Raspberry Pi 3 does.

So if you have power problems with your Raspberry Pi do not automatically suspect the power supply, but check the cables also.

Till next time,
Luc Volders