Category: Hardware

  • Diving into the plcLib Scan Cycle

    Diving into the plcLib Scan Cycle

    The plcLib library implements a scan cycle which has some similarities – and also some important differences – to the traditional scan cycle of an industrial PLC. The scan cycle is defined as the repeating process of reading inputs, performing calculations and updating outputs. The scan cycle of a PLC takes place in well defined…

  • Using the M5Stack CardKB mini keyboard

    Using the M5Stack CardKB mini keyboard

    The M5Stack CardKB is a full specification mini keyboard, with a built-in controller IC. It is supplied with a Grove connector and uses an I2C interface, plus the Wire library, to transfer keypress data to a connected Arduino-compatible microcontroller. Surprisingly, the entire keypad is the size of a credit card. The CardKB module offers a…

  • Using Escape Sequences to Extend plcLib

    Using Escape Sequences to Extend plcLib

    The escape sequence ‘//$’ causes the current line to be ignored by the JavaScript interpreter, but the remainder of the line is passed unaltered to the C++ compiler. Suppose for example, you need to include a servo library in your C++ application. This may be achieved by adding the line ‘//$#include <servo.h>’ at the start…

  • Working with Positive and Negative Logic

    Working with Positive and Negative Logic

    One of the challenges of electronics interfacing is dealing with the wide variety of electronics hardware that may be connected! Internally, a microcontroller deals with digital values that are either true or false, on or off, or 1 or 0. However, there is no single definitive mapping of internal logic values and external voltage levels.…