# Zymkey 4i plus 20x2 LCD I2C Display problem **URL:** \ **Category:** ZYMKEY4\ **Created:** [April 6, 2019, 8:12pm UTC](https://community.zymbit.com/t/zymkey-4i-plus-20x2-lcd-i2c-display-problem/488 "2019-04-06T20:12:20Z")\ **Posts on this page:** 1\ **Showing post:** 4
**Author:** ![Phil\_S\_Zymbit\_1](https://avatars.discourse-cdn.com/v4/letter/p/45deac/32.png) [@Phil\_S\_Zymbit\_1](https://community.zymbit.com/u/Phil_S_Zymbit_1)\ **Post date:** [April 7, 2019, 12:41am UTC](https://community.zymbit.com/t/zymkey-4i-plus-20x2-lcd-i2c-display-problem/488/4 "2019-04-07T00:41:47Z")
Good to hear you resolved you problem ! FYI, the Quality of power supply matters with RPi and with Zymkey. The following explains why: > [@Power Quality - How it Impacts Software & System Reliability](https://community.zymbit.com/t/power-quality-how-it-impacts-software-system-reliability/243): > > Applicable Products The information included in this post applies to all Zymbit security modules. Power & Security Poor power quality can result in unstable and potentially insecure operation of your single board computer (SBC), depending upon it’s design, operating conditions and related system and power components. In this post we will outline the important factors of power quality management and explain how Zymkey manages the security of your device when power quality is poor. Power Qualit… --- _[View the full topic](https://community.zymbit.com/t/zymkey-4i-plus-20x2-lcd-i2c-display-problem/488)._