[SOLVED] USB Connection unstable when using OLED

Development Tools IDE 1.x
1

Hi everyone,

I'm using an Arduino Nano Clone with a CH340G in an enclosure, which blocks the Mini USB Port.

I extended the USB Data lines (D+ and D-) lines and GND with ~10cm of twisted wire to a USB-Port in the front panel of the enclosure.

Simple Sketches like Serial Read upload and work fine, but when using the connected OLED Display (SSD1306, SPI) the CH340G stops responding to the USB Bus.

When using the original onboard USB-Port, everything works fine.

Is there something wrong with using the following pins for software SPI?

#define OLED_MOSI   13
#define OLED_CLK   A0
#define OLED_DC    8
#define OLED_CS    7
#define OLED_RESET 12

Is 10cm of unshielded wire already too much for a stable USB?

lg, couka

2

Alright, I found the problem.
The black front panel and black zipties hid the fact, that the OLED and USB shared a GND connection which wasn't connected to anything else (aka. floating) D'uh!

Switching on too many pixels at the same time probably pulled the "fake GND" high enough to mess up the USB communication.

Being too lazy to go and get the continuity tester cost me 3 hours, terrific.

Time to go to bed, I guess ^^