#caliper #hardware #metrology #protocols with oscilloscope photos.
on 02021-11-06#hardware by thamart63@gmail: “Data are transmitted in a continuous data stream when the #caliper is switched on; Each complete dataset consists of a series of 24 bits; The caliper uses a 1.5V logic level, which means that we need to amplify the signal to make it compatible with #Arduino’s 5V logic; Data are transmitted by means of a data line and a clock line; The logic level of the data line needs to be read on the transition of the clock line from HIGH to LOW; Between each series of 24 bits there is a longer period during which CLK remains HIGH; The first bit is always high and does not have any proper meaning; The next bits codify the value of the caliper reading, starting with the least significant bit (LSB); In mm–mode the resulting value corresponds to the caliper measurement multiplied by 100. E.g. 1,5mm will produce the readout 150; Bit 21 is the sign bit: if bit 21 is HIGH, the value is negative.” He used a divider three 10kΩ resistors across the Arduino’s 5V supply to run the 1.5V caliper between 1.66V and 3.33V above Arduino’s ground, eliminating the need for level shifters. #metrology #protocols
on 02021-11-06apparently some #caliper #hardware, even US$5 plastic calipers, has SPI data streams in it that tell you what it's measuring. #metrology
on 02020-11-18