Measuring battery voltage using PRoC (CYBLE-012011-00) | Cypress Semiconductor
Measuring battery voltage using PRoC (CYBLE-012011-00)
In my project, I would like to monitor the battery voltage using a CYBLE-012011-00 module.
I currently have a BLE Pioneer Kit with an EZ-BLE PRoC Evaluation Board (CYBLE-012011-EVAL).
There seems to be several ways to achieve this, but I am interested in the method used in the 'BLE_Battery_Level' example project.
Also, I think the same approach is explained here (http://www.cypress.com/blog/psoc-hacker-blog/measuring-vdd-battery-volts...).
From what I understand, the method in the example project is as follows:
1. By setting the reference voltage of the ADC to internal 1.024V with bypass enabled, an external capacitor connected to VREF of the module is charged to 1.024V.
2. Then, the reference voltage of the ADC is swapped to the battery voltage, VDD, and the ADC value of the external capacitor is read.
3. The voltage of the battery is calculated accordingly.
One thing that I don't understand is why is it necessary to connect J2 pin P3 to J3 pin VREF. This is indicated in the documentation of the example project. Is there a capacitor connected to P3 on the Pioneer Kit? I cannot find any indication of a capacitor connected to P3 in the BLE Pioneer Kit Guide. On the other hand, is it necessary to connect an external capacitor to VREF since the module itself has a 1.0uF bypass capacitor connected to VREF?
I may have got the whole principle wrong. Any help is appreciated.