9 Notes on Interfacing with the ATWILC1000-MR110xB

Programmable Pull-Up Resistors

The ATWILC1000-MR110xB module provides programmable pull-up resistors on various pins. The purpose of these resistors is to keep any unused input pins from floating, which causes excess current to flow through the input buffer from the VDDIO supply. Any unused pin on the device must leave these pull-up resistors enabled, so that the pin will not float. The default state at power-up is for the pull-up resistor to be enabled; however, any pin that is used must have the pull-up resistor disabled. This is so if any pins are driven to a low level while the device is in the low-power sleep state, the current flows from the VDDIO supply through the pull-up resistors, increasing the current consumption of the module. The current through any pull-up resistor that is being driven low is VDDIO/100K because the value of the pull-up resistor is approximately 100kOhm. For VDDIO = 3.3V, the current is approximately 33 µA. The pins that are used and have the pull-up resistor disabled must always be actively driven to either a high or low level and not be allowed to float.