A media processing device is disclosed. An example media processing device includes memory including machine-readable instructions; and a processor to execute the machine-readable instructions to control a printhead assembly, the processor being configured to communicate with the printhead assembly in accordance with a pin configuration, wherein the pin configuration includes pin groups, and each of the pin groups includes a signal line and a reference voltage, wherein the signal line pin is coupled to a source of changing values, and the reference voltage pin is coupled to a constant voltage.