A microcontrolled electrocardiographic monitoring circuit with differential voltage encoding is provided. An input signal path includes an electrode, a low pass filter, and an amplifier, which are each connected in-line. The electrode senses an input signal via a conductive surface and the amplifier outputs a filtered amplified output signal. A microcontroller circuit includes an input codec, an analog-to-digital converter, and an encoder. The analog-to-digital converter is connected to the input signal path through an output of the amplifier and converts the filtered amplified output signal into a data stream of discrete digital values. The encoder determines a differential voltage between a current discrete digital value and a prior discrete digital value in the data stream. Persistent memory is connected to the microcontroller circuit via a peripheral serial interface bus, wherein the differential voltages for each of the discrete digital values in the data stream are stored into the persistent memory.