As we finish off our current run of ArduBat boards, the WiFiBat application is heating up. To better support the 3.3 volt base boards that would be used for a WiFiBat ( like the WeMos D1 ), a voltage jumper was added to the ArduBat II board to select which voltage was needed for the user button pullups.

Also, one of the 10K resistors was labeled BPL to indicate that it sets the Bat Pulse Level. For use with a 5 volt base board ( the Uno R3 ) the BPL resistor will still be 10K. For a 3.3 volt base board ( the WeMos D1 ) the BPL resistor should be set to 5K. ( You can see the PCB layout here )

A new feature that is added to the ArduBat II board is the ability to sample the incoming Vin voltage with an analog input. Two resistors are added to provide a voltage divider that brings the incoming Vin voltage down to 1/10 of its level for sampling. This sampled voltage would be available to the A0 input of the UNO R3, as well as to the default analog input of the WeMos D1, as it is on the same header pin. If Vin sampling is not desired, the two resistors are simply omitted at the time of construction.

As for the voltage jumper, see the images to the right. The top image shows the jumper location for 5 volt operation. Be sure to bridge the connection well away from the 3v pad ... or even better, use a short insulated wire jumper.

The jumper for 3 volt operation is a little simpler, as the pads are just next to each other, as shown in the bottom image. Simply use a clipped capacitor lead to set the jumper.

Be very careful NOT to jumper the 3v and 5v pads together ... bad things are likely to happen ...