Arduino GPS communication problem

Using Arduino Project Guidance
1

Hi to all,

I have a project that include GPS module and Arduino uno.

I use SIM28 as a GPS module, the problem is Arduino can not read any information from GPS
(GPS module itself is working.).

Communication between Arduino and SIM28 is hardware serial RX,TX. When i measure this signal with an oscilloscope

SIM28 TX pin signal is like below;( 3V– 0V square wave)

When i applied this signal to Arduino RX pin square wave has changed to 4 V to 2.8 V.

I figured out that Arduino needs logic level converter which converts 3V to 5V so i used the circuit below:

After that, SIM28 TX signal has changed to 5V-0.6V square wave as expected.(see below)

However, when i applied this signal to arduino RX pin, signal changes to 5V-3V square wave as below, and arduino can not read that signal.

How can I communicate GPS module (SIM28) and Arduino, OR How can i convert my signal to 5V-0V, which will make it meaningful signal for my Arduino.

Thanks in advance.

2

A 5V Arduino can usually read a 3.3V serial signal correctly. However, your scope traces don't make much sense. Do you have the grounds connected together?

Please post a wiring diagram (hand drawn is fine, avoid Fritzing).

3

Thanks for the reply,

Circuit schematic is like below.

Any help?

4

If you bought this from Grove, follow their directions for how to connect it.

5

Show me video.

6