HC-12 serial module loses connectivity switching from USB to battery power

HC-12 serial module loses connectivity switching from USB to battery power

I am sending analog light dependent resistor values from an HC-12 module to another HC-12 module.

The values are transmitted just fine when both modules are connected to their
respective Keyestudio Arduino pro micro via USB.
I can see from the serial monitor that values are being transmitted properly.

When I unplug the USB wire from the transmitter side and supply it with battery power it stops sending values over to the receiver side.

Any ideas why?

Thanks.

knightridar:
HC-12 serial module loses connectivity switching from USB to battery power

I am sending analog light dependent resistor values from an HC-12 module to another HC-12 module.

The values are transmitted just fine when both modules are connected to their
respective Keyestudio Arduino pro micro via USB.
I can see from the serial monitor that values are being transmitted properly.

When I unplug the USB wire from the transmitter side and supply it with battery power it stops sending values over to the receiver side.

Any ideas why?

Thanks.

You need to help us with more information.

Whats the supply voltage to the HC12 when its supposed to be transmitting whilst on battery ?

What is the battery ?

Probably because of a lack of a ground plane. When you power from USB you have a sizeable lump of conductive material connected to ground. This is what makes simple antennas work.

Try mounting your system on a sheet of aluminium and connecting that to your signal ground.

But more information would get something better than a guess.

If switching power is going to be a common practice, you may need to make provision to STOP the transmission while making the power change.

Paul

The supply voltage is 8.2 volts from two 3.7 volt 18650 batteries.

The case holder has an on off switch and they are in series.

I have a step down voltage converter of 3.3 volts on there. So the supply voltage to the hc-12 and arduino is 3.3 volts.

I have the arduino plugged into USB only for troubleshooting purposes so I can view results on the serial monitor.

The battery power switch was on the on position when I unplugged the USB connection from the PC. I’ll try the grounding idea to see if that’s the issue.

I did change both the receiver and transmitter to FU2 power saving mode to save battery life and reduce power consumption. The HC-12 manual is attached. For reference my delay time of 1000ms is sufficient for transmitting data.

It works fine when connected to PC. I have the receiver end powered with a DC variable voltage testing power supply and sometimes a 6 volt solar panel. I also have a 3.3 volt step down converter on the receiver side.

The weird part is sometimes I power the transmitter side with a 5 or 6 volt solar panel and the receiver side with a 6 volt solar panel and I know I am getting sufficient current. The arduino lights turn on and also the motors I have on the receiver side move occasionally when the transmitter and receiver are working properly. I took a look at the serial monitor on the receiver end and it seems the analog sensor values that cause the motors to move stop getting sent for some odd reason.

HC-12-Documentations.pdf (282 KB)

Wow I think the grounding plane idea took care of it. The transmitter seems to be sending photo resistor values and things are moving now again but sometimes pausing when they shouldn’t.

Excuse my ignorance but will a larger metal piece help to create a better ground? I’m using these CH2 connectors as a quick solution.

I’m going to try this during the day time with the solar panels as my power source to see if I get the same results.

20180326_221347-1110x1082.jpg

will a larger metal piece help to create a better ground?

Yes.