Digital caliper gauge

On this page is described an interface to pick out the data from a digital caliper gauge.

Everyone knows the cheap caliper gauges, which are offered with a serial interface in any internet stores. The caliper has a serial data output and so, it spurred the hope of many to be able to attach this good piece to the PC. Here the customer errs.
The problem concerns the serial interface as implemented. It is not the long known asynchronous serial interface that our computer normally uses, but instead, it involves a synchronous serial interface. At the end of the year 2000 I started together with
Lee Studley to decode this interface. In addition, it spawned some discussions in October 2000 in the discussion group CAD_CAM_EDM_DRO . Here you can find a ascertained protocol of the caliper gauge, which served then as basis for programming. Those who continue to pursue this thread, receives for their troubles still more details. On this page is described the building of an interface for the selection of the data from a digital caliper gauge.
The data can be picked out serially at the PC and/or be represented on a LCD display.
The interface functions with the caliper gauges, in whose operating instructions the following minutes are described:

Working way ofinterface:     Synchronus serial
DATA:                                 Binary code, 24 bits, each date wants sends twice
Clock pulse of CP:                 90 kHz
LCD interface (test sample)

Developed operating model

From the interface the following attitudes are possible:
- changing over between
- zeros of the caliper gauge
- current supply of the caliper




Screen shot of the PC software