“Its an analog world”, this reality has always been a point of consideration when designing embedded systems. Since the data we process is done in the forms of binary 0s and 1s, working with components which provide analog data or respond to analog signals is a topic of study for system designers. The contribution of digital controllers to the analog world is enormous, from applications in the home such as speed regulation of fans to Advanced Driver Assistance Systems (ADAS) in Smart Cars, the interaction between Analog quantities with Digital control elements is ever increasing. Designing analog circuits is tedious and time consuming, designers need to be careful about signal aspects such as phase changes, precision of sensors, offsets, etc. On the other hand digital designers work with only 0s and 1s and dont usually understand the niches of analog design. In the world of today, the gap between analog digital design is decreasing as both become increasingly intertwined. Digital design engineers are ever more required to possess analog design skills in developing their designs. This has led to innovations being made in the construction of digital control devices.
Citing the importance of the interaction with analog physical quantities such as temperature, pressure and noting that electronic circuits are in a continuous cycle of downsizing, microcontroller manufacturers started to provide built in Analog to Digital Converters in their products to facilitate system designers and rid them of the need to use external ADCs in their systems. This innovation spurred the development of compact and low cost embedded systems which could now be easily constructed and used due to the removal of the need of external components.
Analog comparators are another type of peripheral devices which have found their way inside the microcontroller. Many microcontrollers today contain several analog comparators which have programmable reference voltages and are configured through code. This alleviates the need for designers of systems to utilize external comparators thus saving space and simplifying end design.
With new systems having to satisfy requirements of cost and space, the demand for digital and analog integration has grown significantly. Microcontroller manufacturers such as Microchip, Atmel, Texas Instruments and others have produced a line of microcontrollers which contain built in analog peripherals such as Digital to Analog Converters and Op-Amps further reducing the need to add external analog circuitry to digital systems and making microcontrollers more versatile for a variety of applications.
DIGITAL TO ANALOG CONVERTERS:
The DAC converters in microcontrollers are usually 8 to 12 bits wide while allowing external reference voltages to be used. A sampling rate of 1Msps allows for the generation of waveforms of high frequency. Further options such as twos compliment on the DAC input data are also provided. The DACs present in the microcontrollers can also be fine tuned by
Other configurable options to adjust output offset, amplification ratio and also synchronizing the outputs of multiple DACs. The DACs are fully integrated in to the architecture and are supported by interrupts that indicate to DAC operations and can be used by engineers with stringent design requirements. Some microcontrollers have dedicated DACs for applications of audio output. These DACs consists of assisting filters implemented within them to carry out equalization and other operations.
Operational Amplifiers are perhaps the most widely used analog components for signal conditioning purposes. The availability of Op-Amps in microcontrollers makes them truly equipped to be used in compact systems where cost and space is a priority. The Op Amps in microcontrollers provide rail to rail single supply operation. Features like the selection of bandwidth, slew rate, signal routing (connections of the op-amp output to a microcontroller pin), use of the op-amp as an inverting or a non-inverting amplifier and the power consumption settings can be set in software. The gain can also be configured using the control registers of the op-amps. Moreover, flexibility is provided by allowing configuration of the op-amp in various circuit configurations like differential amplifiers, unity gain amplifiers for impedance matching thereby taking a lot of circuit designing tasks away from the analog part of the system.
The inclusion of analog modules within microcontrollers makes them suitable for use in portable medical and industrial equipment as well as deployable applications where size and cost are important, as such our Electrical Engineering Community should exploit these new features for maximum benefits in developing indigenous applications.
The writer is Dean Faculty MUET Jamshroro, Sindh