I am pretty new to microcontrollers, so I am sorry if I am asking something stupid.
I am trying to implement a battery check every time my device starts. It reads the value on Pin29 (ADC 3) and converts the value into voltage using formula voltage=3.3*3/65536 which according to my research should be correct.
When the device is connected to USB, it return about 4.8 volts and I can measure the same voltage from the Vsys pin. However if I disconnect the USB and connect 3 x AA battery power to Vsys, it reads only about 3.5 volts. However I can still measure around 4.5 volts on the Vsys pin.
Why is that ?
I am trying to implement a battery check every time my device starts. It reads the value on Pin29 (ADC 3) and converts the value into voltage using formula voltage=3.3*3/65536 which according to my research should be correct.
When the device is connected to USB, it return about 4.8 volts and I can measure the same voltage from the Vsys pin. However if I disconnect the USB and connect 3 x AA battery power to Vsys, it reads only about 3.5 volts. However I can still measure around 4.5 volts on the Vsys pin.
Why is that ?
Statistics: Posted by PetriS — Tue Jan 28, 2025 8:51 pm — Replies 0 — Views 22