This month we up the resolution: an external ADC attached to a node delivers samples with 22 bits of precision. Getting the samples into the microcontroller is easy using its SPI port. Also, we show how to display the results on a PC with a judiciously-modified version of the HTML page from the previous instalment in this series.

One of the pleasing things about electronics is the way you can get inspiration from other projects. In this case it was the reader project ‘Temperature Gradient Meter’ from last month’s issue [1]. Author Dr Dietmar Schröder selected an external type MCP3551 ADC from Microchip for use in his circuit in order to obtain the high precision required to detect minute temperature changes. This device converts voltages to digital values with 22 bits of precision.