SparkFun Forums

[lucashaley]

Hello everyone!

I'm pretty new to Arduino stuff. I'm trying to build a simple capacitive touch button that will connect to a computer by Bluetooth. I'm using a Pro Mini, a Bluetooth Mate Silver, and a 5-button touch breakout. I also have a 4xAA battery pack, with 2300mAh rechargeables.

This setup works when connected through FTDI/USB. When I switch to batteries, it connects but only ever gets -1 through the stream.

Am I missing something simple here?

Thanks for any help!

-Lucas

[trueRF]

The next step is to isolate your bluetooth connection. Use USB power and see if you can't get the bluetooth connection to display a simple printF, to verify the bluetooth is connecting and working properly. If that works then remove the usb power and add the batteries. See if you can get the same printF to work. Then see if you can trigger the printF using the cap sense button.

It's always easier to troubleshoot a smaller piece of a project than to troubleshoot the whole thing.

Good luck!

[lucashaley]

Thanks for the reply!

I've already isolated the connection away from the cap touch, and it definitely works with USB. It also definitely does not work with batteries.

I'm using SoftwareSerial, and sending a mySerial.write() command to send an int, with a delay of 10ms. WIth USB, I can receive the int. Switching over to batteries, my computer never enters the while available>0 block; it just receives a -1.

I'm stumped.

[lyndon]

I haven't used the Arduino myself but I seem to remember that there are 3.3 and 5V versions. Which one is yours? If it's a 5V one, then it's possible that the 6V battery isn't providing enough headroom for the regulator to work.

[jremington]

4xAA rechargeable batteries is more like 4.8 V.

[lyndon]

Yes. I missed the "rechargeable" part!

4xAA rechargeable batteries is more like 4.8 V.

[lucashaley]

It's a 5V arduino mini, so that's probably the problem. I guess there's some tolerance, as it does start up; but maybe there isn't enough juice beyond that to power the bluetooth breakout.

I'll try with a 9V into the raw, and see if that works.

Thanks for your help, I really appreciate it!

-Lucas