How to run a Fio on USB power?

Projects General Guidance
1

Hello everyone,

I am working on a new project using the Arduino Fio. Previously I was always using a LiPo battery with my Fio project but this time I don't need the mobility (just the XBee for wireless com and the small footprint). So I was wondering if and how I could use the mini-USB connector to supply power to the board instead of charging the battery?

A did a few tests and it seems that when I have a LiPo and the mini-USB plugged in, the sketch on the Fio is running while the LiPo is charging. But if I unplug the LiPo, the sketch stops running, although the mini-USB is still providing power to the board (both CHG and ON LEDs are turned on).

I guess I could leave a small LiPo plugged in all the time but it seems wasteful and I would be concerned about overcharging that LiPo. Can I maybe fake the presence of a LiPo by shorting the BAT+ and BAT- pins? If so should I use a simple wire, a resistor (what resistance)?

Thanks in advance for your help.

Cheers,

Tom

2

Since you are starting hack, so do I.

Fio's power supply diagram.

We could bypass max1555, USB 5v to U2 in and gnd to gnd and leave S2 switch off.

Fio's Summary

  • Microcontroller: ATmega328P
  • Operating Voltage: 3.3V
  • Input Voltage: 3.35 -12 V

You're on Your Own!

3

Thanks!

It seems someone asked a similar question to SFE and got a confirmation from them that he wire CHG 5V to BAT + in order to bypass the battery charger.

https://forum.sparkfun.com/viewtopic.php?f=32&t=30899#p137505

However he's not mentioning if he connected BAT - to CHG - in order to ground them together. Do you think it would be better?

Sorry if I am asking an obvious question but I am no expert and I'd rather not fry my brand new Fio.

Cheers,

Tom

4

  1. We could bypass max1555, USB 5v to U2 in and gnd to gnd and leave S2 switch off.
    Need made custom usb cable, not change at board level.

  2. We could bypass max1555 by jumper wire between BAT + and CHG 5V (USB 5V).
    Need standard usb cable, change at board level. short the max1555.

  3. We could bypass max1555 by jumper wire between U2 in and CHG 5V (USB 5V) and and leave S2 switch off.
    Need standard usb cable, change at board level. no short the max1555.

Which way is beter? I don't know. If I were you, I will flip coin.

5

Thanks again for all your help.

6

In case anyone is wondering, method 2 works like a charm (a jumper cable between the BAT + and the CHG 5V pin holes, nothing else).

I haven't tried the other methods because this one was the most obvious to me and these pin holes are clearly marked on the board.