Skip to main content

You are here

Modifying AA Power Board for power switch

14 posts / 0 new
Last post
jon bondy
Modifying AA Power Board for power switch

Has anyone added a power switch to the AA Power Board? Given that the AA Power Board is attached to the JeeNode with about a dozen pins, the usual approach (interrupter between the two boards) is not feasible. Was the AA Power Board designed for this? I cannot find any documentation on the board (Documentation and Full Design Details link from http://jeelabs.com/products/aa-power-board goes nowhere useful)

Ozzy

Follow the link given at the bottom of the page, there is your documentation.

jon bondy

I follow the link. It goes to a page where the only link goes back to the original page. There is no documentation.

martynj

AA Power Board.

Can you handle SMD parts? Order a bare PCB, cut the etch from Vbatt to the chip SHDN pad, replace by Rpullup and a switch to ground.
The LTC3525 spec sheet has guidance on choosing the pullup value.

Ozzy
jon bondy

Thanks, everyone. Looks like power switches were never considered when this board was created. Unfortunately, I only get a few days out of a battery, and I only need to use it for about 10 minutes a day. A power switch option would be very useful for my application.

martynj

Can't you use some of the many node power saving tricks and put the load to sleep?
The AA board quiescent current takes years to drain a full Eneloop.

jon bondy

The board needs to listen until it is commanded to do something. No way to avoid keeping the receiver working, and the processor waiting, is there? The reaction time only needs to be about 0.1 seconds, but I still would need to keep the radio receiver working, and only put the processor to sleep.

martynj

@jon, with the constraint of always listening, how does switching the AA board help?

jon bondy

I need to use it for 15 minutes at 10:00, then 15 minutes at 2:00, then not until the next day. So, if I could turn it on at 10 and off at 10:15, etc, it would mean that I only had to replace the battery every month, not every other day.

martynj

@jon, use the (sloppy but very mean) RFM12B timer to bring the MPU out of deep sleep. Send a 'what time do you have' packet to central, use the reply to adjust the next sleep period...

If there isn't a central to talk to - use a Real Time Clock plug to do the same based on the alarm function.

PavelE

@jon
My .2c : Because it would take quite some time to study and implement all JN power saving techniques - see "Low Power" tag in WebLog, you might better begin with a pack of 3x AA batteries from JL shop or just do it yourself. It will have at least 3x times more power, because AA board is efficient but still just a voltage convertor/booster.

PavelE

@jon
Just do enough search on JL forums (both Generic and Support) and WebBlog ;-)
You need terms: "watchdog" for a way to wake up and "sleep".
There were many discussions quite recently on the forum of what is the most efficient way to sleep and wake up.

PS: RF12 watchdog is more efficient and more precise about wakeup time, but you get very good savings even with one from ATmega itself.

FYI: Some coding masters (like JCW or MartynJ) are talking about more than 12 months battery life from even a 3V "clock cell", but as a beginner, I estimated easily getting about 100-120 days from a single AA cell (i.e. less 1mA total "sleep" current).

martynj

Nah - Jack of All Trades, Master of None. I can't code my way out of a wet paper bag - but I can make electrons go the right way once in a while ;-)

Premium Drupal Themes by Adaptivethemes