How to Choose Microcontroller

It used to be that the number of different microcontroller chips available to the hobbyist was pretty limited. You got to use whatever you could manage to buy from the mail-order chip dealer, and that narrowed down the choice to a small number of chips.

But times have changed. Digikey lists over 16000 different line items under a "microcontroller" search. Which one should a hobbyist with no particular prior experience choose?

Here are some hints. These are particularly aimed at someone trying to pick a microcontroller to use for the first time at least partially as a learning experience, rather than someone who wants to accomplish a particular task.

Update 2009-01-28: This Instructable was recently mentioned in some popular blogs, and is getting a bunch of new readers. Be sure to read the "comments" made by other readers and the responses to them; there's a lot of value in those comments...

step 1What IS a "Microcontroller" ?
If you ever took a very introductory computer course, you probably learned about the major components of ANY computer:A Central Processing Unit or CPU. The part that actually performs logic and mathMemory. Where the computer stores data and instructionsInput and Output or I/O. How the computer…

step 2Show Stoppers
There are a number design considerations that might immediately reduce your number of choices a great deal. Programability and Reprogramability: At this point in time, I would say that a hobbyist should only consider microcontrollers that have internal flash or eeprom program memory and can be …

step 3Thoughts about Architectures
The "architecture" of a microcontroller refers to the philosophy of the internal implementation, sort of. It includes details like how many "registers" there are, and how "general purpose" those registers are, whether code can execute out of data memory, whether the peripherals are treated like …

step 4Thoughts about Hardware Tools
Minimally, you'll need some sort of programmer to load the program into the microcontroller. These vary wildly in cost. It's pretty common for manufacturers to offer some low-cost programmer so that people can "evaluate" their microcontrollers without risking too much cash (or requiring director…

step 5Thoughts about Software Tools
All of the microcontrollers mentioned here have some level of standard tools (at least an assembler) provided by the manufacturer. Most have "Integrated Development Environments" (IDE) that allow integrated use of an editor (that you won't like) with the assmebler, some compilers, and a simulato…

step 6The $100 Paradox
If your budget extends as far as $100 for the computing hardware, it's worth noting that you have bought your way into an interesting realm of "bang for buck." "About" $100 will buy: - Relatively fancy development board for most micros; covering a wide range of processors and performances (incl…

step 7Microchip PIC Microcontrollers
The Microchip PIC microcontrollers were perhaps the first that were marketed to the hobbyist and student community, one of the first microcontrollers to be offered in a relatively small package (18 pin DIP) and one of the first to implement flash or eeprom program memory (in the PIC16C84 in 1993)…

step 8Resources for Microchip PIC
Microchip the ManufacturerPICList mailing list repository of knowlege[http://techtrain.microchip.com/masters2004/(kgmnvafutocq2355egt11231)/downloads/classlist.htm Microchip Masters Conference 2004 Downloads] Tutorials and presentations[http://techtrain.microchip.com/masters2005/(kgmnvafutocq235…

step 9Atmel AVR
As near as I can tell, Atmel came along and decided to steal some of Microchip's business by offering "similar but better" chips. Some things they did right, some things they didn't do so well. But the Atmel AVR chips have also gained a lot of popularity amoung hobbyists, and we get to cash in o…

step 10Resources for Atmel AVR
Atmel the ManufacturerAVR Freaks Despite the amateurish name, this is a REALLY good site.PIC vs. AVR smackdown A comparison between PIC and AVRAVR Butterfly The AVR "Butterfly" evaluation board is a phenomenal value at the current price of $20.Another Butterfly vendorGCC supports all but th…

step 11Intel 8051 and variants
Intel invented the 8051 architecture a long time ago, and garnered some hobbyist interest with the 8052BASIC chip, which contained a basic interpretter in masked ROM and allowed one to build a very small BASIC based computer. Since then the architecture has been licensed and/or stolen by MANY v…

step 12Resources for 8051
8052.com site Massive amounts of info.Atmel 8051s Atmel does 8051s as well as AVR and ARMNXP (Philips) 8051 89LPC controllers.RAMTron micros 8051s with FRAM non-volatile memorySilicon Labs Neat 8051s including high performance ADCs. Also the smallest 8051; 11pins in a 3x3mm QFN. Cheap US…

step 13Freescale (Motorola) 68HC908, HCS08
Motorola (well, now Freescale) has several lines of popular microcontrollers, the most accessible of which seems to be the flash-based 68HC908 and/or HCS08 or RS08 (all the same or very similar architectures, with some renaming and assorted minor differences) series. Traditionally, Motorola chip…

step 14Texas Instrument MSP430 micropower Microcontrollers
Texas Instruments garnered some interest when they introduced (bought?) their MSP430 series of extemely low-power microcontrollers. Until recently, most of the MSP430s were only available in assorted hobbyist-unfriendly SMT packages, but a couple of recent chips have been introduced in DIP pac…

step 15ARM microcontrollers
ARM is a company that designs microprocessor architetcures, and licenses them to manufacturers who build actual chips. The ARM is a 32bit true RISC architecture, and scales upwards to CPUs with floating point hardware and clocks speeds of several hundred MHz. If you have a palmtop, it probably …

step 16Other Interesting Microcontrollers
- Cypress PSOC - Renesas (Hitachi) H8, M6

step 17Modules, bootloaders, and "hidden" microcontrollers
A number of companies have made a business of selling "modules" , usually incorporating some sort of microcontroller and some of its support components with a high-level-lanaguge development environment, some sort of chip-programming capability, and communications. This gets rid of the need for …

step 18Zilog Z8 and Z80 chips
Zilog (inventor of the famous Z80 microprocessor chip) has updated versions of the Z80 in microcontroller form, and also updated versions of the even older Z8 architecture. Both have flash memory and some interesting peripherals , and inexpensive "evaluation boards" that include a C compiler. A…

step 19Win Valuable Prizes
Periodically, many of the manufacturers of microcontrollers will sponsor "Design Contests" where engineers all over will be challenged to come up with a particularly clever design using a particular microcontroller. The idea is to entice engineers into looking at THEIR chips even if they're alre…

step 20Try it Online: Virtual Labs
Tech Online is a pretty good website for technical News in general, and they've apparently implemented something they call "Virtual Labs" that will allow you to try out a vendor's development system over the internet with nothing but a browser on your end. I used this for the first time as part …

step 21Free Stuff!
In the old days, companies would mail datasheets and databooks to just about anyone who asked. The web has done away with the need for most of that, and many vendors seem to have taken the money they saved on postage and used it to make their sample program more accessible.The way "free samples"…

sumber : http://www.instructables.com/id/How-to-choose-a-MicroController/

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Microcontroller

A microcontroller (also microcontroller unit, MCU or µC) is a small computer on a single integrated circuit consisting of a relatively simple CPU combined with support functions such as a crystal oscillator, timers, watchdog timer, serial and analog I/O etc. Program memory in the form of NOR flash or OTP ROM is also often included on chip, as well as a typically small amount of RAM. Microcontrollers are designed for small or dedicated applications. Thus, in contrast to the microprocessors used in personal computers and other high-performance or general purpose applications, simplicity is emphasized.

Some microcontrollers may operate at clock rate frequencies as low as 4 kHz, as this is adequate for many typical applications, enabling low power consumption (milliwatts or microwatts). They will generally have the ability to retain functionality while waiting for an event such as a button press or other interrupt; power consumption while sleeping (CPU clock and most peripherals off) may be just nanowatts, making many of them well suited for long lasting battery applications. Other microcontrollers may serve performance-critical roles, where they may need to act more like a digital signal processor (DSP), with higher clock speeds and power consumption.

Microcontrollers are used in automatically controlled products and devices, such as automobile engine control systems, remote controls, office machines, appliances, power tools, and toys. By reducing the size and cost compared to a design that uses a separate microprocessor, memory, and input/output devices, microcontrollers make it economical to digitally control even more devices and processes. Mixed signal microcontrollers are common, integrating analog components needed to control non-digital electronic systems.
articel source : wikipedia.com

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Progammable Logic Controllers (PLC)

Dalam bidang industri penggunaan mesin otomatis dan pemrosesan secara otomatis merupakan hal yang umum. Sistem prengontrolan dengan elektromekanik yang menggunakan relay-relay mempunyai banyak kelemahan, diantaranya kontak-kontak yang dipakai mudah aus karena panas / terbakar atau karena hubung singkat, membutuhkan biaya yang besar saat instalasi, pemeliharaan dan modifikasi dari sistem yang telah dibuat jika dikemudian hari dipertlukan modifikasi.
Dengan menggunakan PLC hal-hal ini dapat diatasii, karena sistem PLC mengintegrasikan berbagai macam komponen yang berdiri sendiri menjadi suatu sistem kendali terpadu dan dengan mudah merenovasi tanpa harus mengganti semua instrumen yang ada

KONSEP PROGRAMMABLE LOGIC CONTROLLERS (PLC)
Konsep dari PLC sesuai dengan namanya adsalah sebagai berikut :
Programmable : menunjukkan kemampuannya yang dapat dengan mudah diubah-ubah sesuai program yang dibuat dan kemampuannya dalam hal memori program yang telah dibuat.
Logic : menunjukkan kemampuannya dalam memproses input secara aritmetik (ALU), yaitu melakukjan operasi membandingkan, menjumlahkan, mengalikan, membagi, mengurangi dan negasi.
Controller : menunjukkan kemampuannya dalam mengontrol dan mengatur proses sehingga menghasilkan output yang diinginkan.

FUNGSI PROGRAMMABLE LOGIC CONTROLLERS (PLC)
Fungsi dan kegunaan dari PLC dapat dikatakan hampir tidak terbatas. Tapi dalam prakteknya dapat dibagi secara umum dan khusus.
Secara umum fungsi dari PLC adalah sebagai berikut :
1. Kontrol Sekensial
PLC memroses input sinyal biner menjadi output yang digunakan untuk keperluan pemrosesan teknik secara berurutan (sekuensial), disini PLC menjaga agar semua step / langkah dalam proses sekuensial berlangsung dalam urutan yang tepat.
2. Monitoring Plant
PLC secara terus menerus memonitor suatu sistem (misalnya temperatur, tekanan, tingkat ketinggian) dan mengambil tindakan yang diperlukan sehubungan dengan proses yang dikontrol (misalnya nilai sudah melebihi batas) atau menampilkan pesan tersebut ke operator.

BAHASA PEMOGRAMAN
Terdapat banyak pilihan bahasa untuk membuat program dalam PLC. Masing-masing bahasa mempunyai keuntungan dan kerugian tergantung dari sudut pandang kita sebagai user / pemogram. Pada umumnya terdapat 2 bahasa pemograman sederhana dari PLC , yaitu pemograman diagram ladder dan bahasa instruction list. (mnemonic code).Diagram Ladder adalah bahasa yang dimiliki oleh setiap PLC.

LADDER DIAGRAM
Diagram Ladder menggambarkan program dalam bentuk grafik. Diagram ini dikembangkan dari kontak-kontak relay yang terstruktur yang menggambarkan aliran arus listrik. Dalam diagram ladder terdapat dua buah garis vertical dimana garis vertical sebelah kiri dihubungkan dengan sumber tegangan positip catu daya dan garis sebelah kanan dihubungkan dengan sumber tegangan negatip catu daya.
Program ladder ditulis menggunakan bentuk pictorial atau simbol yang secara umum mirip dengan rangkaian kontrol relay. Program ditampilkan pada layar dengan elemen-elemen seperti normally open contact, normally closed contact, timer, counter, sequencer dll ditampilkan seperti dalam bentuk pictorial.
Dibawah kondisi yang benar, listrik dapat mengalir dari rel sebelah kiri ke rel sebelah kanan, jalur rel seperti ini disebut sebagai ladder line (garis tangga). Peraturan secara umum di dalam menggambarkan program ladder diagram adalah :
 Daya mengalir dari rel kiri ke rel kanan
 Output koil tidak boleh dihubungkan secara langsung di rel sebelah kiri.
 Tidak ada kontak yang diletakkan disebelah kanan output coil
 Hanya diperbolehkan satu output koil pada ladder line.
Diantar dua garis ini dipasang kontak-kontak yang menggambarkan kontrol dari switch, sensor atau output. Satu baris dari diagram disebut dengan satu rung. Input menggunakan symbol [ ] (kontak normally open) dan [/] (kontak normally close). Output mempunyai symbol ( ) yang terletak paling kanan.

2. Prinsip-prinsip Ladder Diagram PLC
Untuk memperlihatkan hubungan antara satu rangkaian fisik dengan ladder diagram yang mempresentasikannya, lihatlah rangkaian motor listrik pada gambar dibawah ini.
Motor dihubungkan ke sumber daya melalui 3 saklar yang dirangkai secara seri ditambah saklar over load sebagai pengaman. Motor akan menyala bila seluruh saklar dalam kondisi menutup.
Kesimpulan :
 Ladder diagram tersusun dari dua garis vertical yang mewakili rel daya
 Diantara garis vertikal tersebut disusun garis horizontal yang disebut rung (anak tangga) yang berfungsi untukmenempatkan komponen kontrol sistem.

3. Praktek memori Circuit (Latch)
Rangkaian yang bersifat mengingat kondisi sebelumnya seringkali dibutuhkan dalam kontrol logic. Pada rangkaian ini hasil keluaran dikunci (latching) dengan menggunakan kontak hasil keluaran itu sendiri, sehingga walaupun input sudah berubah, kondisi output tetap.

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