BS2 Brownout Indicator / Alarm

Saildude

Is there an easy way to have an alarm or indicator that shows that a BS2 has stopped due to low voltage?

I am working on a project and put the BS2 into the Prototype Board - things ran fine for a short time and then the project just died - the indicator LED's on the board were still on but the processor had stopped. I will leave out my flailing to find the problem- quite embarrassing actually - turned out my battery pack had just ran out of energy.

But is there a way to put some sort of indicator for the next time this happens so there will be some sort of indication of what is wrong?

The project will sometimes be looked after by people that are not tech orientated and save me some thinking if it happens to me.

The battery pack is 5 Ni-Mhd cells - nominal voltage of 1.2 v per cell. Part of the time it might also use one of your plug into the wall 7.5vdc power supplies

Thanks for any ideas

Sapphire

You could connect a LED to an unused pin, with a resistor to ground. At the start of your program, make that pin HIGH and turn on the LED. If power runs down and the BS2 shuts down, the pin will not be high, and the LED will turn off.

kwinn

Google "low battery voltage indicator ic" for a selection of circuits that can monitor the battery independent of the BS2

Saildude

Thanks much both of you, gives me something to think about.

For the short term since I have seen this once, the standard thing to try will be to put in fresh batteries, also since this will be used mostly a single day, I can put fresh rechargeable batteries at the start of the day.

I might in the long term add a NC relay to the system so when the relay is off a red alarm light comes on and drive the relay with an always on output that is only off when the processor is not rumming

Chris Savage

A simple brownout alarm is to have a piezo play a tone at the beginning of the program. If the program restarts, it will play again.

xanadu

You're starting out with 6v which is low for most of the boards Parallax sells. Any chance you can up the input voltage? Seems like it would make it a lot less prone to brownouts.

The low voltage LED or buzzer is still good to have, I would use an external IC like kwinn mentioned and monitor the VIN. You's probably want a light to turn ON for low voltage, people don't notice things that are off. Most of these chips can also detect over current and over voltage, all good stuff with customer facing tech.

In a pinch you got these guys - http://www.ebay.com/itm/GT56-Mini-DC-0-100V-Red-LED-3-Digital-Display-Voltage-Voltmeter-Panel-Motorcycle/171222756281

Saildude

the voltage is nominal 6.0 but most of the time it is around 7.0, that is a limit of the batteries, it is a Parallax pack and I have been using the same battery pack for several months while I learned how to program the stamp and develop the program. having 27 LED's that turn on and off is a bit more of a drain than a plain stamp - if my math is correct the display should run all day on a set of batteries, the problem I got into was not bothering to recharge the batteries for several months.

to up the voltage would require a 6 cell holder or some combination to get to 6 cells

thanks