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woodrow
6 Posts |
 Posted - 21 May 2002 : 14:32:35
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I'm looking for the easiest way to add a battery-based power supply to my Bitsy development platform. Does ADS have a simple solution off the shelf? I see in one of the product photos some sort of battery pack mounted underneath the board (although it looks quite large!)(http://support.eurotech-inc.com/developers/images/BitsyWireless.gif).
Update 29-Apr-2008 by ljoy: Updated link |
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akidder
1519 Posts |
Posted - 28 May 2002 : 10:35:09
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Thanks for your inquiry. The demonstration system shown in that photo illustrates one way to mechanically mount a Bitsy with a AA battery pack, but it's not a configuration we stock.
Powering your Bitsy only from Batteries
Powering your Bitsy from batteries is pretty easy to do: Simply connect the batteries in series and run them into the DCIN pins of J3 (unless you have reverse-polarity protection, this connection is recommended over the VBATT power inputs).
Note that NiMH batteries will give you about four times as long a life as alkaline batteries of the same size. [A battery expert questioned this statment, stating that "primary batteries typically have higher capacity than rechargables unless the drain is high." He suggests L91, AA-size Lithium batteries (review)where long-lasting, high-drain primary (non-rechargeable) cells are required.]
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Drew Kidder
ADS Technology Transfer
Edited by akidder 17-Mar-2004: Strike out claim that NiMH has better capacity than alkalines.
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akidder
1519 Posts |
Posted - 30 May 2002 : 14:16:59
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On the Bitsy Personality Board...
If you're using the ADS Bitsy Personality Board (aka "Connector Board"), the DCIN power input is on J16.
If you fuse and reverse-polarity protect the batteries, you can also hook them into the battery connector, J7. (On the Rev 1 boards currently in production, the battery charging circuit is bypassed; the J7 inputs are connected directly to VBATT.)
Edited by akidder 8-Jul-2002: Add link for fuse & reverse-polarity protection. |
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woodrow
6 Posts |
Posted - 30 May 2002 : 14:56:08
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OK, out of curiosity, it looks like the power supply provided
with the Personality Board provides 5v, 12v, & grnd? (black, gray,
and yellow). The black and gray go to J16 pin 3, the yellow to
pin 2, and there's a shunt between pin 2 and pin 1. What's
going on there, and do I need to worry about the dual voltages
when I move to battery power? |
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akidder
1519 Posts |
Posted - 30 May 2002 : 17:33:23
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Take a look at the pinout for the 610111-80010 cable, which we just posted. We supply 12V and GND to the Bitsy.
The main thing to watch when running on batteries is that you have adequate voltage for the backlight you're using. 5V backlight inverters are available, and some support wider input voltage ranges. |
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woodrow
6 Posts |
Posted - 31 May 2002 : 09:44:38
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So hooking a battery pack to connector board J7 will power the Bitsy, but won't power the backlight. I should expect the LCD to work just fine though, right?
Also, the manual states that the battery input has "optimized power efficiency". Can someone describe that optimization in more detail? |
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akidder
1519 Posts |
Posted - 31 May 2002 : 10:09:02
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Correct. You can power the backlight directly, or run the backlight voltage through the Bitsy (gives you control over intensity & on/off, which is useful for prolonging battery life).
The DCIN power goes through a diode, then mixes with the VBATT voltage. If you hook DC power to the VBATT input instead of the DCIN, you save yourself a voltage drop of 0.2 to 0.3V, which can amount to as much as 1/4W power savings at full load. Every mW counts in battery-powered systems. |
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rabarton
1 Posts |
Posted - 04 Sep 2002 : 12:03:37
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I'm looking for the best way to add backup battery power to our Bitsy system, so that when power disappears from the DC_IN input, the system will go to sleep and the RAM and clock time will be preserved. I noted the narrow voltage range on the J.50 "backup battery power" input (after I tried connecting 2 AA's to this input, and it didn't work). Im thinking that a 3.0V linear regulator and 3-4 AA's on this input is the best way to proceed. Is there an easier solution here?
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dbrisbois
27 Posts |
Posted - 04 Mar 2003 : 10:25:49
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| We have attempted a similar method of maintaining the RTC. Our backup battery runs through a regulator to BAT_POS (J3.50). Unfortunately, the RTC does not appear to be running when power is removed from DC_IN. How can we get the RTC to persist over a power loss? |
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Richard-b
1 Posts |
Posted - 10 Apr 2003 : 08:50:37
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quote:
[i]Originally posted by dbrisbois[/i]
[br]We have attempted a similar method of maintaining the RTC. Backup battery to BAT_POS (J3.50). Unfortunately, the RTC does not appear to be running when power is removed from VBATT_POS. How can we get the RTC to persist over a power loss?
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Edited by - Richard-b on 10 Apr 2003 08:54:53 |
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