# Troubleshooting

- No pixels visible on the display
  1. Check +5v and Gnd connections between Arduino and GLCD panel
  2. Check all data and command pins are wired according to the datasheet and matching the configuration settings – this is the most common cure to this problem.
  3. Check the datasheet for your panel to verify appropriate timing values are set in the configuration file.
  4. Check contrast voltage (typically between -3 and -4 volts) on contrast-in pin of LCD panel. While the sketch is operating, try gradually adjusting the pot through its range. Some displays are very sensitive to this setting.
  5. Check sketch has compiled ok and downloaded to Arduino.
  6. Run GLCDDiags test sketch.
- All pixels are dark
  1. Check contrast voltage (typically between -3 and -4 volts) on contrast-in pin of LCD panel. While the sketch is operating, try gradually adjusting the pot through its range. Some displays are very sensitive to this setting.
- Left and right side of image reversed
  1. Swap CSEL1 and CSEL2 wires (or swap pin assignments in header file)
- No Serial port diagnostic information
  1. Verify the code is compiling and properly uploading
  2. Disonnect glcd wires to ensure that no pins are in conflict with the serial port pins

Diagnostic Sketch

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