Choosing a Microcontroller Architecture Feb 18, 2013 Bill Giovino v1.1 An Overview of the Microcontroller Marketplace 1

What You Will Learn Today What is a Microcontroller? What is a Microprocessor? Are Digital Signal Processors (DSP) scary? Show me a roadmap Importance of Development Tools Different Major Vendors 2

Microcontroller vs. Microprocessor The lines are blurred Both may contain peripherals Both can contain RAM A device with program memory (Flash, ROM) will always be a microcontroller A device with no Program Memory or RAM will always be a microprocessor A device with no Program Memory, and has RAM – it just might be a Microcontroller

Microcontroller Applications Control- oriented applications Senses external events Controls external events Write your own code

Microcontroller Applications Microcontrollers are primarily used in control-oriented applications that are interrupt-driven, sensing and controlling external events. The external environment is detected and outputs are sent to drivers/actuators that control events. Here, we see a typical example of an embedded system using a microcontroller. The microcontroller-based system takes information from the outside world by reading the value of digital position devices, such as switches, and reading analog signals from temperature sensors. Waveforms generated by timers control the LCD display and motors. A digital output pin drives an LED on and off. The system efficiently communicates with other microcontrollers in its network by a commonly available CAN bus network.

Microprocessor Applications Need raw horsepower Running high performance applications and many tasks at once Write your own code

What is a Digital Signal Processor (DSP)? Used for precision processing of digitized analog signals Uniquely designed to perform a multiplication and an add in one complex instruction (Multiply-Accumulate) Uses complex instructions to perform many simultaneous operations in a small amount of time Not well suited to control-oriented tasks Usually more expensive than a microcontroller Usually draws more power than a microcontroller More complex to program than a microcontroller Driven by available, pre-written software to perform specific tasks like image processing, video processing, audio processing

What to choose? Go with a microcontroller if the task is control-oriented, interrupt driven, and/or bit intensive Go with a microprocessor if you have lots of code and so many tasks you need an RTOS Go with a DSP if you are doing intensive analog signal processing and the math gives you a headache

Roadmaps Get You There A roadmap shows a vendor will develop code-compatible variants of a microcontroller – Today, pin-compatible roadmaps are crucial A roadmap shows a vendor’s commitment to a product line A roadmap shows you can upgrade your system if your code gets bigger, or the system gets more complex An orphan device is outside of the roadmap and has no pin- compatible siblings – Sometimes made for one customer – Subject to discontinuance – There may be no bug fixes

Development Tools For ALL CORES, the quality of the Development Tools are the gating criteria Development board selection can make or break any product line The usability of a microcontroller is proportional to the total number of development boards and compilers available, plus the QUALITY of tech support supplied by the vendor The usability of a microprocessor is proportional to the number of RTOS and compilers available, plus the quality of support by the vendor A core is your hand is just a square piece of plastic - tools must be used to make it do anything useful A core with poor or no development tools is like a Ferrari with a poor or no steering wheel - all that power & it can't be used to do anything!

Development Tools - Compilers You can’t program a microcontroller without one – without a compiler a microcontroller is just a dumb piece of plastic Program it in C – go ahead! It helps to have an underlying understanding of the microcontroller’s architecture and assembly instructions to write efficient C code

Choosing a Compiler There’s water that’s free from the tap, and there’s water you can buy. There are free compilers, and there are compilers you have to pay for Compilers you can buy from IAR, Keil, etc have more optimizations and so create more efficient code Compilers you can buy come with technical support

Development Boards Development boards can make or break a product family A development board allows you to test the target microcontroller in system without building your own hardware Development boards are not “one size fits all” Development boards for motor control, home automation, LCD control are all different Development boards allow you to become comfortable with the target microcontroller so you know you are making the right sourcing decision – Or making a mistake

Development Board Fun Features Is it modular? Is the debug interface USB? Battery backup? What are the networking options: – Ethernet – WiFi – CAN – LIN – Mobile phone Display options: – LCD – Eink – Blinking LEDs Memory Options – External SD Card – Flash memory – Expandable Flash Sensors – Accelerometer – Temperature sensor – Light sensor Are there other development boards for this microcontroller family? Is the quality consistent across all development boards Are the interfaces consistent across all development boards?

Choose a Vendor Before you choose a core, choose a vendor Your potential long-term relationship with the vendor determines the potential long-term success of using the microcontroller Things go wrong. Your fault, the vendor’s fault, nobody’s fault. Your choice of vendor is important for when things go wrong.

Some Major Microcontroller Vendors

Major Microcontroller Vendors Analog Devices - serious Analog 8051 microcontroller with high accuracy ADC Atmel – long history with 8-bit and ARM, AVR has fanatical following Freescale – History with 8-bit and 32-bit, ARM competes with internal 32-bit Infineon – Strong 16-bit player Maxim – gets confused with the racy magazine, fast 8-bit Microchip – consistent and reliable major 8-bit player with a rabid following, 32-bit PIC32 competes with ARM NXP – low power ARM, no 8-bit Renesas – lots of options to choose from thanks to mergers Silicon Labs – extremely low power 8-bit with precision analog, and maybe the lowest power ARM Cortex-M3 STMicroelectronics – Major 8-bit player, wants to own all the ARM sockets Texas Instruments – low power 16-bit MSP430 endures forever, major ARM player, now owns the 8-bit COP8 from NSC

Choosing a Vendor: Making a Decision Look at Development Tools – Most important criteria – How many development boards? – Cheap/free boards & compilers? Go where people like you are talking online – Vendor forums – LinkedIn Groups LinkedIn is our Facebook People using their real names will give you honest feedback Can you get them on the phone? Then look at price and depth

The End Part 1 Next: The Architectures