nRF radio on different power supply

[Leo Yang]

Hello, 

I developed a board with E73-2G4M08S1C(nRF52840) as its main MCU. I would like to develop a simple radio project on this board with power supplied from battery instead of USB.

The transmitter works fine when powered from USB, the receiver can receive the packet sent from the transmitter.

But the receiver can't receive the packet when powered from a coin battery(LIR2032H). 

Here's my schematic:

Hardware: E73-2G4M08S1C(nRF52840)

Software: peripheral/radio/transmitter & receiver

SDK version: nRF52 SDK 17.1.0

I think the code is fine because the two situation are sharing the same code.

When transmitting RF signal, the antenna might draw a large amount of current. I monitored Vdd on oscilloscope, but the voltage almost maintain the same.

I also downloaded the tramitter project to the official nRF52840-DK. The receiver receives no packet when powered from 3V coin cell, but works when powered from USB.

Could you give me any suggestion?

Thanks a lot  for your help!

[Leo Yang]

Hi Jared,

=> I redefined UART Tx/Rx pins to avoid powed from USB.

Sorry for the confusion. UART pins have nothing to do with power supply source.

I don't  want nRF52840 DK to be powered from USB. 

I test on different power source separately which means I test with coin cell only and see what's wrong. And I need UART for debugging. That's why I redefined default UART Tx/Rx pins to others.

I also test the program on 2 custom board I just soldered and it's fine to transmit 2.4GHz RF with coin cell.

The issue is more likely to be my problem. I'll update the case when I figure it out.

Thank you!

Leo

[Jared]

Ok,

Yes, please update the case if you find the root cause.

regards

Jared