IoT Thermal Chart Recorder



This is the latest outcome in a long running set of projects looking at how to visualise or manifest digital information within real world, domestic environments. My current work looks at how to signal ongoing streams of data in a cheap and effective way. To do this I have build a Chart Recorder using a small Thermal Printer.

Chart Recorders are the traditional way of recording constantly fluctuating data streams. Normally using a moving pen and a roll of chart paper, they have familiar aesthetic and often used to represent seismographs, lie detectors, ECG machines etc.

The mini thermal printer is a staple output tool for Arduino, Raspberry Pi and Physical Computing projects. They’re simple to get working, ad there’s plenty of documentation and libraries available on line. They’re normally used when a ‘take away’ outcome is required – a printed out receipt, or a personalised piece of information that the user can take with them. However I’m interested in seeing how they can be used effectively as signage, or persistent, slowly changing displays. These could be linked to the Internet of Things to provide ambient feedback on a range of data sources. Perhaps showing household energy use, or local environmental information such as weather or tides.

Using thermal paper means that it’s easy to represent slowly changing data without having to constantly power a visual display. The drawback is that it introduces a consumable, with the paper having to be restocked periodically. This isn’t particularly costly though (receipt paper is mass produced to be cheap, and can be sourced recycled and BPA chemical free), and the fact that the paper does need to be purchased, even for a few pence, could be used as a feature of the device – perhaps incentivising certain behaviours.

The printer is controlled by an Arduino Yun, which draws in data over WiFi. This also controls the stepper motor to spool up the paper on the other side of the display. Further development could use the gearing of the printer to operate the opposite spool as well.

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