# Power-up issue in RN2483 **URL:** \ **Category:** Hardware\ **Created:** [June 18, 2018, 7:35am UTC](https://www.thethingsnetwork.org/forum/t/power-up-issue-in-rn2483/15121 "2018-06-18T07:35:46Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![lalit\_breadware](https://www.thethingsnetwork.org/forum/letter_avatar_proxy/v4/letter/l/47e85d/32.png) [@lalit\_breadware](https://www.thethingsnetwork.org/forum/u/lalit_breadware)\ **Post date:** [June 18, 2018, 7:35am UTC](https://www.thethingsnetwork.org/forum/t/power-up-issue-in-rn2483/15121/1 "2018-06-18T07:35:46Z")
Hi Everyone, I am currently testing my first node using Arduino Mega and RN2483. Facing Power-up issue: RN2483 module board is powered by 3.3V supply of Arduino Mega. After switching on, I measured voltage on TX, RX, GPIO10 & GPIO11 pins of RN2483. Following are the measured voltage values: TX - 0.36V RX - 0.88V GPIO10 - 0.92V GPIO11 - 1.72V Are we supposed to get these values. I have attached the schematic for reference. ![Capture](https://www.thethingsnetwork.org/forum/uploads/default/original/2X/8/8ac2bbfdf139e0311badd535039f4f1f76017172.PNG) Even after initializing UART communication & sending character ‘X’ from Arduino, these values remain same. Reset doesn’t work on RN2483. Has anyone else encountered this - and what could my actions be going forward? Thanks. Lalit ---
**Author:** ![BoRRoZ](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/borroz/32/44234_2.png) [@BoRRoZ](https://www.thethingsnetwork.org/forum/u/BoRRoZ)\ **Post date:** [June 18, 2018, 9:53am UTC](https://www.thethingsnetwork.org/forum/t/power-up-issue-in-rn2483/15121/2 "2018-06-18T09:53:14Z")
decouple the 2 zeners on rx and tx and measure again… is that your 'level converter ? _better use something like this :_ ![](https://www.thethingsnetwork.org/forum/uploads/default/original/2X/c/c9ff4b9cde25641ca045dbdb42319b2658f458a2.jpg) - [https://www.ebay.com/itm/1-Set-2-channel-Bi-Directional-Logic-Level-Shifter-Converter-3-3V-5V-For-Arduino/253293305210](https://www.ebay.com/itm/1-Set-2-channel-Bi-Directional-Logic-Level-Shifter-Converter-3-3V-5V-For-Arduino/253293305210) ---
**Author:** ![lalit\_breadware](https://www.thethingsnetwork.org/forum/letter_avatar_proxy/v4/letter/l/47e85d/32.png) [@lalit\_breadware](https://www.thethingsnetwork.org/forum/u/lalit_breadware)\ **Post date:** [June 18, 2018, 10:06am UTC](https://www.thethingsnetwork.org/forum/t/power-up-issue-in-rn2483/15121/3 "2018-06-18T10:06:22Z")
Those are ESD Protection Diode [http://www.vishay.com/docs/81851/vesd03a1.pdf](http://www.vishay.com/docs/81851/vesd03a1.pdf) with reverse stand-off voltage of 3.3V. Should I remove them and check again? ---
**Author:** ![BoRRoZ](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/borroz/32/44234_2.png) [@BoRRoZ](https://www.thethingsnetwork.org/forum/u/BoRRoZ)\ **Post date:** [June 18, 2018, 10:09am UTC](https://www.thethingsnetwork.org/forum/t/power-up-issue-in-rn2483/15121/4 "2018-06-18T10:09:28Z")
on an UART bus ? yeah sure check again without them but not with the rn2483 connected ---
**Author:** ![lalit\_breadware](https://www.thethingsnetwork.org/forum/letter_avatar_proxy/v4/letter/l/47e85d/32.png) [@lalit\_breadware](https://www.thethingsnetwork.org/forum/u/lalit_breadware)\ **Post date:** [June 18, 2018, 10:14am UTC](https://www.thethingsnetwork.org/forum/t/power-up-issue-in-rn2483/15121/5 "2018-06-18T10:14:45Z")
Its a plug n play Lorawan module with user accessible UART pins. I will test it without them. Thank you. ---
**Author:** ![BoRRoZ](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/borroz/32/44234_2.png) [@BoRRoZ](https://www.thethingsnetwork.org/forum/u/BoRRoZ)\ **Post date:** [June 18, 2018, 10:17am UTC](https://www.thethingsnetwork.org/forum/t/power-up-issue-in-rn2483/15121/6 "2018-06-18T10:17:24Z")
just remember that the output from your arduino mega is 5v and that the RN2483 is max 3.6 v ---
**Author:** ![lalit\_breadware](https://www.thethingsnetwork.org/forum/letter_avatar_proxy/v4/letter/l/47e85d/32.png) [@lalit\_breadware](https://www.thethingsnetwork.org/forum/u/lalit_breadware)\ **Post date:** [June 18, 2018, 10:22am UTC](https://www.thethingsnetwork.org/forum/t/power-up-issue-in-rn2483/15121/7 "2018-06-18T10:22:11Z")
Yeah. I am using a shield on Arduino Mega with leve) converter. TX line from level converter to RN2483 is working fine (measured 3.24V, sending character ‘X’). Issue arises when I connect and power-up RN2483 module, TX line from level converter drops down to 0.88V. ---
**Author:** ![lalit\_breadware](https://www.thethingsnetwork.org/forum/letter_avatar_proxy/v4/letter/l/47e85d/32.png) [@lalit\_breadware](https://www.thethingsnetwork.org/forum/u/lalit_breadware)\ **Post date:** [June 18, 2018, 11:12am UTC](https://www.thethingsnetwork.org/forum/t/power-up-issue-in-rn2483/15121/9 "2018-06-18T11:12:40Z")
Removed ESD protection diode and tested again, working fine now; wrongly selected 3.3V reverse stand-off ESD. Whenever UART lines were exceeding 3.3V (due to some noise in the line), ESD diode was clamping them to GND. A good lesson learnt. Thanks a lot BoRRoz. ---
**Author:** ![BoRRoZ](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/borroz/32/44234_2.png) [@BoRRoZ](https://www.thethingsnetwork.org/forum/u/BoRRoZ)\ **Post date:** [June 18, 2018, 11:22am UTC](https://www.thethingsnetwork.org/forum/t/power-up-issue-in-rn2483/15121/10 "2018-06-18T11:22:53Z")