October 1, 2023


Digitally first class

A digital caliper connected to a tablet computer

Custom Interface Adds USB And Wi-Fi To Digital Calipers

Though outdated-college machinists commonly desire the mechanical vernier scale on their trusty calipers, lots of consumers today purchase calipers with a electronic readout. These styles usually occur with extra options like differential measurements, or a “hold” perform for those people circumstances exactly where you have to maneuver the instrument someplace deep inside of a equipment. Yet another helpful feature is a data connection that allows you log your measurements on a laptop straight as a substitute of manually coming into all the values.

The VINCA-branded caliper that [Liba2k] bought has these kinds of a data hyperlink characteristic, which involves a USB adapter that’s marketed independently. There is a micro-USB connector on the resource itself, but alternatively of employing a USB interface, this is used to carry a proprietary serial protocol — a structure decision that should to be categorised as a felony if you inquire us. Fairly than shopping for the official USB adapter, [Liba2k] decoded the protocol and designed his possess interface identified as VINCA Reader that can join by both USB or Wi-Fi.

The serial format turned out to be a easy serial bus that clocks out 24 bits at a time. In buy to adapt its 1.2 V sign level to the 3.3 V utilized by an ESP32, [Liba2k] created a easy level shifter circuit employing a handful of discrete components. The ESP can converse with the computer via its Wi-Fi interface, for which [Liba2k] wrote a spreadsheet-like application alternatively, an standard USB cable can be linked to emulate a keyboard for use with any other software package.

With its added Wi-Fi characteristic, the VINCA Reader is really far more total than the official USB adapter, and will possibly be more cost-effective as properly. The serial interface appears to be frequent to all caliper makers, even though several went for a more wise connector than micro-USB. An automated readout system is significantly useful if you have to make 1000’s of similar measurements.