Maxim has unveiled a smart force reference design that allows engineers to evaluate and deploy HMI (human machine interface) devices. According to the company, the MAXREFDES82# system board performs accurate measurement of both downward force and centre of mass by collecting responses from four load cells using the MAX11254, a 24bit, 6-channel ADC that samples at a rate of 64ks/s.

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Operating as both a weigh scale and a touch interface with force sensing, the MAXREFDES82# measures weight and centre of mass up to 780g and consumes less than 50mA during normal operation. The unit’s four load cells are mounted on a quadrant plane to detect touch forces applied on the flat plastic plate. Depending on the force applied to each individual load cell, the system displays the total force magnitude and the coordinates of the force centre. Force magnitude and coordinates are scanned approximately every 10ms.

An on-board TFT LCD module digitally shows the forces on each individual load cell and the total force applied on the top plate and graphically displays the force magnitude and the coordinates of the force centre. A micro-USB cable connected to a PC powers the MAXREFDES82#.

The MAXREFDES82# costs $99. Hardware and firmware design files, as well as test data, are available online at no charge.