Measuring battery voltage using PRoC (CYBLE-012011-00)

[japac_1817436]

Hi all,

   

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-psoc4).

       

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[0] to J3 pin VREF. This is indicated in the documentation of the example project. Is there a capacitor connected to P3[0] on the Pioneer Kit? I cannot find any indication of a capacitor connected to P3[0] 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.

   

Thank you.

   

Jaemann

[rola_264706]

Here is a program there is a PDF in the program files that explains the process.

[rola_264706]

The cap is highlighted in this picture.

   

[rola_264706]

You don't need to add a cap as it is already there.  C15

[japac_1817436]

Thanks bobgoar, but that was the exact example project I was looking at and was confused about.

   

However, I think I have got things sorted out.

   

Pin P3[0] (or some other pin that can be read from the ADC) is required to be connected to VREF and consequently to the bypass capacitor within the module in order to read the voltage across the bypass capacitor after it has been charged by the internal reference voltage.