Why are Vusb and Vbat digital inputs to the microprocessor? Are they needed and must the voltage divider be used to lower it’s voltage? And last thing is the 3V input on the D+ pin of the mini usb necessary? What is its function?
They are not required, but may be useful.
Vusb allows the SW to know if the scope is connected to USB or not (for example to show a charging icon).
Vbat (if conected to a A/D input) allows to monitor the battery voltage, so the SW can show the state of charge.
The voltage dividers are required as Vusb and Vbat are higher than the allowed input range (3V).
The pullup at D+ is used to indicate the USB mode when connecting to an USB host.
Thanks thats great help.
hi, the Vusb is used to detect where the voltage resource from, USB or Battety… and the Vbat is to monitor the voltage of battery . the 3V resource and resistance is essential for the USB communication. thanks.