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akidder
1519 Posts |
 Posted - 25 Jul 2007 : 19:47:03
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quote:
Originally posted by rdall in topic 2051
Using Bitsy Xb with recent CE Kernel Image version 5.00.32.
We want to power the Bitsy at close to its minimum specified voltage of 5VDC. We find that voltages as low as 9VDC applied to VBATTPOS cause misbehaviour, failure to wake up from sleep or vice-versa.
Is there any way to get around this? Are these behaviours caused by power fail interrupt behaviour or the like?
The main internal rail of the system is 5VDC, so it seems that a DC supply above the input regulator drop out voltage should be able to do the job.
Thanks,
Rick Dall, Senior Electronic Engineer
QRS Diagnostic LLC
Email [removed]
The BitsyXb should operate at 5V, but it's expected that you might hit some trouble below 6V with the voltage monitor (DC_GOOD). See Notes 4, 5 and 15 in Chapter 6 of the BitsyXb User Manual (topic 2096) for details.
However, the trip level should be below 6V. You shouldn't be seeing any trouble at 9V. Can you let us know details about how you are testing? We'll be glad to investigate. |
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rdall
16 Posts |
Posted - 30 Jul 2007 : 17:56:16
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Thanks Drew. As posted before:
- Using Bitsy Xb with recent CE Kernel Image version 5.00.32.
- Applying an adjustable DC voltage to "VBATTPOS" (J3, Pin 38) and GND (J3, pins 46,47,49).
- The system will boot with a DC voltage as low as 6VDC.
- I can then put the system to sleep, by pulling /RQONOFF at pin 45 to GND.
- When I then try to wake the system by again pulling /RQONOFF to GND, it goes into a dysfunctional current consuming (~200mA) state without display output.
- I can recover from the dysfunctional state by removing and reapplying the power rail. This is obviously not workable as the program memory is erased by doing this.
Would you please check if any BitsyXb you have to hand behaves this way?
Thanks,
Rick
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jjoseph
47 Posts |
Posted - 02 Aug 2007 : 18:15:10
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Hi Rick
We have been talking via email to resolve this issue but I wanted to address this in the forum post.
I tried running the BitsyXb at lower voltages and did not see the problem you found with the dysfunctional state. There may be a problem with your particular board and I have recommended that you send it back for repair. |
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