Author Archives: Shawon Shahryiar

Tiva C GPIOs

fetured

GPIOs are the basic interfaces of any microcontroller. Without GPIOs we won’t have any other way to use a micro and it will be nothing more different than a chunk of well-fabricated silicon. Through them we can interface both transducers or sensors and actuators. We can also connect other devices like a display, external devices and so on. As with any ARM microcontroller, the GPIOs of TM4C12x Tiva C ARM microcontrollers are very elaborate, having many options that are usually unavailable in common 8-bit microcontrollers. The one we are interested in – the TM4C123GH6PMI – is a 64-pin micro with more than 40 usable GPIO pins. Here in this post we will explore the GPIOs of TIVA C micros.

tm4c123gh6pm

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Tiva C Clock System

Tiva C Launchpad External Clocks

The clock system of a microcontroller is a fundamental element. Clock system provides the heart-beat needed to keep applications running in a synchronous manner. In the case of Tiva C micros the clock system is as much as sophisticated and elaborate as with any other ARM micros. In this post we will explore this basic block of Tiva C micros. We will see that the clock system is a network of different clock sources and internal units that are intertwined in a complex but easy manner.

TM4C123x Features

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The World of TI’s Tiva C MCUs

launchpad-tivac-01

Most of us who work with electronics know the name of Texas Instruments (TI) as a manufacturer of several important digital and analogue ICs as well as fancy sophisticated scientific calculators. However many people don’t know that TI is also a manufacturer of some of industry’s best microcontrollers. TI’s portfolio of micros is pretty large. ARM micros are getting popular day-by-day and on that family of micros TI has some of the best devices one can imagine. One such family from TI is the Tiva C series. Enter the TM4C123x Tiva C micros – one of the best possible combination of high-end hardware ever integrated with an ARM Cortex M4.

launchpad-tivac-01

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STM32’s internal RTC

VBAT Pin

A Real Time Clock (RTC) is a timing element dedicated for keeping time. In many applications, especially where precise timed-operations are needed to be performed, a RTC is a very useful tool. Examples of such applications apart from clocks and watches include washing machines, medicine dispensers, data loggers, etc. Basically a RTC is a timer-counter but unlike other timers of a MCU it is much more accurate. Previous to this post, we explored STM32 timers but those were useful for applications like PWM generation, time-bases and other waveform-related tasks. Those were not suitable for precise time-keeping. In most 8-bit MCUs like the regular PICs and AVRs, there are no built-in RTC modules and so we need to use dedicated RTC chips like the popular DS1302 or PCF8563 when we need an on-board precise time-keeping device. Those chips also need some additional circuitry, wiring and circuit board space. At present, however, most modern MCUs come packed with literally every possible hardware a designer may think of. It is only up to a designer to decide which resources to use from a modern-era micro to meet a specific design goal. Gone are the days when MCUs were manufactured for application specific requirements and also gone are the days of implementing and involving multiple assets in a design. Thus cost, time and space are dramatically reduced, resulting smarter, sleeker and smaller affordable devices. Fortunately STM32s are in that list of those modern era microcontrollers. STM32 MCUs come with built-in RTC modules that require no additional hardware support. This tutorial covers basic features of STM32’s internal RTC and  how to use it for time-keeping applications.

Block_Diagram_Simplified

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XMega DAC

XMega DAC Register Map

In embedded systems, oftentimes it is needed to generate analog outputs from a microcontroller. Examples of such include, generating audio tones, voice, music, smooth continuous waveforms, function generators, voltage reference generators, etc. Traditionally in such cases the most common techniques applied are based on Pulse Width Modulation (PWM), resistor networks and external Digital-to-Analog Converter (DAC) chips like MCP4921. The aforementioned techniques have different individual limitations and moreover require external hardware interfacing, adding complexities and extra cost to projects.  XMega micros are equipped with 12 bit fast DACs apart from PWM blocks and again it proves itself to be a very versatile family of microcontrollers. In this post we will have a look into this block.

DAC Internal Block Diagram

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