Announcement: Power Cape (UPS)

Hello fellow enthusiasts,

Please check out my Power Cape and let me know what you think. Yes, they are for sale but I would also value your feedback.


Looks interesting for building a robot.

Hello fellow enthusiasts,

Please check out my Power Cape and let me know what you think. Yes, they
are for sale but I would also value your feedback.

I seem to have bought the last one in stock with stacking headers.

Be sure to register your capes on and

My "dream" power cape would include an RTC and the ability to set
alarms to wake-up and/or power-up the board. I also dream of a power
cape that would allow the battery and cape to still fit in an Altoids
tin, sandwiching the battery between the boards and eliminating any
connectors components that would extrude beyond those boundaries.
Then, insulating the tin with a non-conductive material would allow
for containing a running Bone and I'd just make a cut-out for the USB

That said, I really like what you've created, which is why I bought one. :slight_smile:

Do you have a recommended battery supplier?

Hi Jason,

Thank you for the comments (and the order!). The first batch of boards was very small due to parts availability. Still waiting on a zener to come back in stock (current estimate is beginning of May).

The cape firmware does currently allow for a timeout to be set that will power the BB back on. The cape also monitors 3V3 so it knows when the BB has powered down and then will then cut 5V (and reset the timeout if you’ve set one). It is my intention to add a RTC to the firmware but I really need to create a kernel driver for it to provide the proper RTC interface and so that everything else is accessible through sysfs.

I have thought about moving the components to the “bottom” of the board to make the top “slick”. I’d probably have to scoot a component or two around but that should be completely doable. These lithium battery packs get pretty small. My final prototype now lives in a Logic Supply case which I think is a pretty nice setup. Without the stacking connectors, the cover just needs to be raised one position. Photo here.

The reason that I put the JST connector onto the cape is because the lithium packs from AdaFruit and SparkFun seem to all have them pre-installed. The battery in the pic is from AdaFruit and is 1200mAh. That runs an idling BBB for nearly 3 hours!



As for adding a RTC to the board all the drivers for that are already in the kernel. Just add one of the following RTC chips: DS3232 (high accuracy), DS1338C, DS1339C, or DS1374 all of which can attach to the same i2c pins as your cape EEPROM. Given the pcb cad files I’m guessing it would take 5-10 minutes tops to add a RTC to your board and getting the software to use it another hour tops.


True, I could do it with another part fairly easily. I was trying to keep down the parts count (and cost) since the micro already has a 32kHz clock and keeps time. My pick and place machine (me) gets grumpy if the board has too many parts. :wink:

I’ll add a supported I2C RTC device to the wish list for the A1 boards.


If I remember from previous discussion on this list, the issue with using the onboard RTC was keeping it powered and running with everything else powered down