Hi Dialog,
I am using P0_1 for ADC to get the battery voltage of Lithium Battery. Known that the range of Lithium battery is 3.58V-4.15V. So, I use a voltage divider circuit to measure the voltage. But, I can only get a very low voltage on the point between two series resistors which attached to P0_1. When I cut off the lead, the voltage become correct.
I will attache the circuit and measurements.
附件:
Device:
Hi Oliver_Zero,
Thats because you use allready the internal attenuator of the 58x (which is essentially a voltage divider) and you have also attached an external voltage divider as well, that is never going to give you the actual battery voltage. The internal attenuator will alter the ADC impedance of the ADC input to a much lower value that it would be without the attenuator (infinite) and that eventualy will cause innaccuracies to the value that you get from the ADC. Try to use the ADC without the attenuator with only the external voltage divider, this will also cause a drift from the values of the battery but not that large.
Thanks MT_dialog
Hi, MT_dialog.
Thanks a lot for your help. I can measure the battery voltage now.
Best Regards
Oliver.