A microcontrolled electrocardiographic monitoring circuit (10) with differential voltage encoding is provided. An input signal path (23) includes an electrode (12a), a low pass filter (13a), and an amplifier (13b), which are each connected in-line. The electrode (12a) senses an input signal via a conductive surface and the amplifier (13b) outputs a filtered amplified output signal. A microcontroller circuit (11) includes an input codec, an analog-to-digital converter (14), and an encoder (33). The analog-to-digital converter (14) is connected to the input signal path (23) through an output of the amplifier (13b) and converts the filtered amplified output signal into a data stream (31) of discrete digital values. The encoder (33) determines a differential voltage between a current discrete digital value and a prior discrete digital value in the data stream (31). Persistent memory (17) is connected to the microcontroller circuit (11) via a peripheral serial interface bus (18), wherein the differential voltages for each of the discrete digital values in the data stream (31) are stored into the persistent memory (17).
