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WP34S: Reset when printing statistical registers?
07-04-2014, 06:51 PM
Post: #31
RE: WP34S: Reset when printing statistical registers?
(07-03-2014 09:24 AM)pito Wrote:  Do we measure the battery voltage (BATT) under full load??
When not, the BATT does not show the proper numbers..

I agree on your conclusion but I can't help it. The battery monitor is more software than hardware. The brown out detection circuit is programmed to a threshold and signals if the current supply voltage is below or above the programmed value. To detect the actual voltage the software updates the threshold in regular intervals and monitors the result bit. The main problem is the time the circuit takes to stabilize after a change to the threshold. So the algorithm is:

  1. Get the current bit value
  2. Is the supply voltage below the threshold? If yes decrease the value, otherwise increase it.
  3. Wait for the next interrupt to repeat the cycle.

The time between interrupts is needed for the output to stabilize. If I want to measure under load I'd need to switch to high speed whenever I adjust the threshold value, i. e. all the time. This would deplete the batteries unnecessarily.

You can measure the voltage under load by executing BATT in a programmed loop and let it run for a while. A running program is executed at full speed unless you set SLOW mode which roughly halves the speed.

Marcus von Cube
Wehrheim, Germany
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RE: WP34S: Reset when printing statistical registers? - Marcus von Cube - 07-04-2014 06:51 PM

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