In order for the Notecard, or any device, to interpret logic-level signals there must be a common ground between the two devices. So in this case, your hardware connection should require 3 wires as follows:
Okay, that’s good. I had to ask just to make sure.
Do you have an oscilloscope or any other UART based peripheral, so we can confirm you are seeing UART activity using the serial communication example (without the Notecard present)?
Unfortunately, I don’t have an instrument, but I tried to communicate the V2 with Wio Terminal via UART. Wio Terminal can receive the data which I send from the V2.
Are you using the Grove port to supply the Notecard’s power and ground, or something else?
Which Notecarrier are you using?
What input are you using to power the Notecard, V+?
Lastly, can you send a picture of your setup?
1. Are you using the Grove port to supply the Notecard’s power and ground, or something else?
— Yes, I’m using V2’s grove port to power up the notecard.
2. Which Notecarrier are you using?
— Notecarrier A
3. What input are you using to power the Notecard, V+ ?
— Yes, V+ of the Notecard. (which is connected to +5V to UART grove)
We have looked at your pics, read the available technical information for the M5Stack UnitV2, and we are concerned you may be overextending your power budget.
If you have a LiPo battery available, we would like for you to do a quick test and connect it to the Notecarrier-A and see if it resolves the issue. This would ensure there is enough power available to the system.
If it works, then we understand the problem. If not, then we can rule it out and pursue other potential problems.
Unfortunately, at this moment I don’t have the +5 V battery, so I just plug the USB on Notecarried and remove the V+ connection between Notecarrier and V2. But still I’m hitting the same issue.
Actually, I’m using Jupyter Notebook to do this development.