Strange Bluetooth Ardu Pro mini 3v3 Behavior, Insight needed

Development Boards Arduino
1

Hello All.

I am having some issues with my Pro Mini 328 3v3 and a BTM-182 blue tooth module.

The main issue i am having is that i cant connect to the BT adapter with my computer when its powered by batteries.

I have 3, 3v CR2032 button style batteries connected to the raw input on the arduino.

When i try to connect powered by batteries, i cant.

however when i plug the 3v3 FTDI break out board, i can connect effortlessly. If i switch over to batteries and disconnect the FTDI,

I am able to get an output for about a minute and then things go haywire.

It drops the connection and i cant reconnect unless i plug in the FTDI.

I was looking at the VCC and ground connections with an OSCOPE and found that just before it breaks connection, there is significant noise on the Oscope.

I have a good feeling that is why i am loosing the connection but i dont know how to go about correcting it.

A brief overview of the project.

I am sending accelerometer values over BT and viewing on hyperterminal.

The BTM is still set to factory specs, 19200 baud, 8n1.

I also cant seem to make any changes to the BT module.

I am unsure how to do it.

Do i write a program to send the AT commands over, or should i use Hyperterm?

Thanks all.

-Erik

2

Erik,

My SWAG is that your cells aren’t able to sustain the operating current you need.

Do you have the CR2032’s in series or parallel?

How much current do the Arduino (and whatever you’re feeding through it) draw?

By how much does the voltage coming out of the cells drop during that first minute of operation after you disconnect the FTDI?

Eric