Power-up issue in RN2483

End Devices (Nodes) Hardware
1

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

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

2

decouple the 2 zeners on rx and tx and measure again… is that your 'level converter ?

better use something like this :

3

Those are ESD Protection Diode http://www.vishay.com/docs/81851/vesd03a1.pdf with reverse stand-off voltage of 3.3V. Should I remove them and check again?

4

on an UART bus ? yeah sure check again without them but not with the rn2483 connected

5

Its a plug n play Lorawan module with user accessible UART pins.
I will test it without them.

Thank you.

6

just remember that the output from your arduino mega is 5v and that the RN2483 is max 3.6 v

1 Like
7

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.

9

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.