MPUs and MCUs
PIC and AVR MCUs are making edge node development easy
By Ross Satchell, technical marketing engineer, Microchip Technology W
● Sensor interface ● Low power ● Physical size ● Security
Let’s take a closer look at those four considerations in order.
Sensor interfaces
Sensor interfaces come in several common varieties. Commonly, the embedded system designer uses: analog sensors which output a continuously varying voltage or current, digital sensors which can use logic levels or data streams such as serial communications, variable pulse width modulation (PWM) such as throttle position sensors, or time of flight sensors used in range sensing. Let’s look at some of those in more detail.
n Analog sensor interfaces:
Having the option to choose between discrete analog vs on-chip integrated analog means the user can select the right analog tool for the job. By using a larger process technology on our silicon wafers, this means the on-chip analog peripheral is far less susceptible to crosstalk as well as inductive or capacitive noise that increases as manufacturers move to much smaller process technologies. Microchip’s integrated on-chip analog peripherals are configurable just as the user would configure any other peripheral. By having peripherals integrated the user can also read them as inputs, for example the user might want to know what the inputs of the comparator are during a particular stage of the program.
Let’s look at some of those analog peripherals starting with op-amps. Integrated op-amps: Microchip’s integrated op-amps have the associated passive circuitry on-chip as well, such as the internal resistor ladder allowing programmable gain to be set and even changed during runtime. Furthermore, the op-amp configuration can
40 April 2023
also be changed during runtime meaning the user can switch between inverting, non- inverting, unity gain (voltage follower), and custom discrete configurations during runtime, giving far greater flexibility than using discrete hardware alone, while minimising the costs associated with discrete hardware. Usually when using discrete hardware, the designer is forced to design their mixed signal application to handle worst-case scenarios and thus some performance sacrifices must be made. However, using integrated analog peripherals allows the user to build some intelligence into their application, where the embedded system can change op-amp gain, configuration or even cascade them on the fly. This means the user can design their application to optimally handle each different scenario, while taking advantage of the lower power consumption of peripherals when compared to software-centric solutions. It needs to be said that the integrated op- amp is not a “magic bullet”, and as such they won’t always be the most suitable for every possible application. For example, if the user finds themselves developing an application
Components in Electronics
where they need superior analog performance, dual-supply configuration, or a specialty variant then they should look at Microchip’s wide range of discrete op-amps. This is a perfect case of choosing the right tool for the job at hand.
Analog to Digital Converter (ADC) with enhanced features: Microchip’s enhanced ADC peripheral features include hardware functions that traditionally were only available using software-centric drivers, such as accumulation, burst modes, averaging, window comparison, and filtering. As always, these ADC peripherals can use external reference voltages, but they can also use multiple different internal reference voltages along with auto-conversion triggering. This results in the user having access to the hardware functions that can be used while the CPU is in low-power modes. For example, the user can configure an ADC window comparison that only wakes the CPU when the input signal is outside that window so that the CPU can process that input signal appropriately. This means the CPU sees far fewer wakes and results in significant power
savings, vital in low-power applications. This has the added benefit of reducing system and therefore sensor noise, since digital components such as clocks and PWM can be disabled when not in use.
n Digital sensor interfaces:
Usually when an embedded system designer starts developing an application they will attempt, as much as reasonably possible, to coalesce their sensors and devices around a single voltage domain. This is to reduce the added complexity, increased propagation delay, and associated Bill of Materials (BOM) and PCB real estate costs associated with using level shifting circuitry. Multi-Voltage I/O: Multi-Voltage I/O (MVIO) allows the user to set up one full I/O port using a second voltage domain between 1.62V and 5.5V. The MVIO peripheral uses only 500nA when in use, making it ideal for low-power applications. All digital behaviour in serial protocols (I2C, SPI, USART), PWM, and GPIO all just work on the second voltage domain with input Schmitt Trigger levels being scaled according to the second voltage
www.cieonline.co.uk
hen designing robust edge nodes, the embedded system designer often has four considerations at the forefront of their mind:
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62
