# SerLCD Teensy Issues

**URL:** <https://community.sparkfun.com/t/serlcd-teensy-issues/43039>\
**Category:** Displays\
**Created:** [November 10, 2021, 5:54am UTC](https://community.sparkfun.com/t/serlcd-teensy-issues/43039 "2021-11-10T05:54:03Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![benlucian](https://avatars.discourse-cdn.com/v4/letter/b/7feea3/32.png) [@benlucian](https://community.sparkfun.com/u/benlucian)\
**Post date:** [November 10, 2021, 5:54am UTC](https://community.sparkfun.com/t/serlcd-teensy-issues/43039/1 "2021-11-10T05:54:03Z")

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Hi guys, Hope you can help me, first time poster so please be kind 🙂

I am attempting to get the SparkFun 16x2 SerLCD - RGB Text (Qwiic) working with my Teensy 3.5.

I have hooked it up via I2C to the correct pins on the Teensy and am running the default “Example1-Hello World” sketch.

The I2C wires are less than 130mm / 5inches long and connected from JST to screw terminals. I have connected VIN to RAW as per I2C Hookup Guide and Ground to Negative as per guide.

I am having two issues:

- Wherever I am not writing a character I get a filled square. I have looked in the documentation and can’t see mention and this doesn’t match photos in the hookup guide.
  
- The “lcd.setCursor(0, 1);” seems to be ignored and the values are being drawn to different positions that are occasionally shifting.
  
What I have tried:  
- adding delays (as clock speed of Teensy is very 120Hz.
  
- shortening I2C Wires - though I have had much longer work with other displays in past
  
- tried other examples - with similar result
  
- only updating if result is different to previous result
  
Any suggestions would be appreciated thankyou!

I will post to Teensy forums as well to see if they have ideas from that direction.

 ![20211110_153810.jpg](https://canada1.discourse-cdn.com/sparkfun/original/3X/6/a/6a2312e3396a9789184cdd0c9eaf4796d06b1125.jpeg)

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<div class="post-metadata">

**Author:** ![benlucian](https://avatars.discourse-cdn.com/v4/letter/b/7feea3/32.png) [@benlucian](https://community.sparkfun.com/u/benlucian)\
**Post date:** [November 10, 2021, 6:29am UTC](https://community.sparkfun.com/t/serlcd-teensy-issues/43039/2 "2021-11-10T06:29:05Z")

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Solved by switching to SUART from I2C!

Will leave the above up so that if anyone comes across this problem they have a clue. 🙂