1 Microcontrollers you should know about Thomas Edwards .

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Microcontrollers you should know about

Thomas Edwards

http://www.t11s.com

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What is a Microcontroller (uC)?

• A “computer-on-a-chip”

• Simple but reliable way to control electromechanical systems

• No boot-up / no hard drives

• Smaller than a PC

• Less power/heat than a PC

• Cheaper than a PC

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What can you do with a uC?

• Flash LEDs in a particular way

• Move a motor in a pre-programmed fashion

• Have LEDs, motors, servos respond to switch or sensor inputs

• Connect devices to the Internet

• Much more!

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What does a uC need?

• Power Supply – the right voltage

• Support circuitry – different needs for different uCs– Voltage regulators– Crystals or resonators– Serial, USB, or Ethernet interfaces

• Programmer (usually PC based)

• Proto-board to assemble circuitry on

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Basic Stamps

• Very popular!• Runs PBASIC interpreter• No Analog inputs…

• BS2 ($49)– 4,000 instructions per sec.– 16 Digital I/O pins– 32 bytes RAM– ~500 instructions

• http://www.parallax.com

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Other Types of Stamp• BS Rev. Dx ($34)

– BS1 w. proto area– 16 bytes ram– 80 instructions– ~2,000 instructions./s

• BS1 USB ($39)– $39.95

• BS2px ($79)– 38 bytes RAM– ~4,000 instructions– ~19,000 instructions/s

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Programming BS in PBASIC

For b2= 0 to 5

high 1

pause 100

low 1

pause 100

next b2

N VAR BYTE

TOP: FOR N = 0 TO 100

SEROUT 16, 84, 10, ["N = ", DEC N, CR]

PAUSE 500

NEXT

GOTO TOP

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Parallax Sensors

• Sensors made with the BS in mind

• But you could use them with other uCs

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Basic Stamp Pros/Cons

Cons:

• Expensive

• Small memories

• No A/D inputs

Pros:

• Popular

• Easy to use

• Tons of online documentation

• Many sensors available

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“Fish Pain” Maquette

• Basic Stamp reads button, drives fish animation

• Winbond Chipcoder voice board

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Microchip PIC

• Array of cheap but powerful microcontrollers

• $1-$10• Natively programmed in assembly

language• Lots of functionality (A/D, PWM, timers,

counters)

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Some (of the hundreds) of PICs• PIC12C508/509 (Small 8-pin package, internal oscillator, popular in small

designs such as the iPod remote) • PIC12F629/675/683 • PIC16F84 (generally considered obsolete, but still popular) • PIC16F84A (upgrade to above, some versions do 20 MHz, 1:1 compatible

with PIC16F84) • PIC16F628 (replaces the PIC16F84. The 16F628A has more program

memory and fully compatible) • PIC16F88 (an excellent all-round 18-pin PICmicro) • The PIC16F87X family (The PIC16F84's "big brothers", with lots of built in

hardware similar to the 16F88. Quite common in hobby projects.) • PIC16F877 (RS232, Parallel Port Interface, PWM and much more) • PIC18F452 • PIC18F4550 and relatives (Full-speed USB support, all sorts of inbuilt

hardware. Very powerful and versatile)

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PIC Assembly Language

• Harvard Architecture– Separate instructions and data

• Memory “Banks”

• Many, many special registers for config

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PIC Cvoid serTxIsr(void){

if (idxTxbufPut != idxTxbufGet) { TXREG = txBuf[idxTxbufGet]; idxTxbufGet = (++idxTxbufGet) &

SER_TXBUF_MASK; } else { PIE1_TXIE = 0; //Disable USART Transmit

interrupt when nothing more to TX }}

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PICs – Pin “Overloading”

• Pins can serve four or more different functions

• Flexibility to meet project needs with minimal pins

• Often difficult to properly configure

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“Sycophant”

• Head mounted on R/C car chassis

• Follows viewers as they move down hall

• Sharp active IR sensors• PIC 16F648A controller• L293 Motor controller• Windbond Chipcorder

audio chip

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Atmel AVR

• Family of microcontrollers– ATmega– ATtiny

• $1-$15

• Similar to PIC, but slightly easier to program in assembly language

• “Religious discussions” about PIC versus AVR

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Training Boards

• PIC18F458 training board ($44.90 http://www.futurlec.com/PIC18F458Training.shtml)

• ATMega163 training board ($44.90 http://www.futurlec.com/ATMegaTraining.shtml )

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PIC/AVR Pros/ConsCons:• Tough to program in

assembler/C• Programmer board

required (sometimes ~$50)

• Many different types of PIC, programs don’t port between them

Pros:• Very cheap• Many interfaces and

functions (A/D, PWM, timers, counters, I2C)

• Lots of online documentation & support

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CUBLOC CB220• Basic Stamp “pin compatible”• But much more powerful…

– 80 KB flash instruction memory– 4 KB EEPROM– 2 KB Data RAM– 36,000 instructions per second– A/D (up to 5V)

• Built-in 5V regulator• Based on AVR

• CB220 $34, Proto board $5• http://www.comfiletech.com

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CUBLOC BASICDim f_pos_1 As ByteDim f_pres_1 As Byte

Input 5 'P0 / Pin 5 as InputOpencom 0,9600,3,32,32 'open RS-232 channel to XportOpencom 1,9600,3,32,32 'open serial channel to Servo ControllerBclr 1,1 'clear channel 1 tx buffer

On timer(10) Gosub a2d 'every 100 msOn Recv0 Gosub servo_move 'on UDP in from Xport

DoLoop

a2d:f_pres_1=Adin(0)>>2 'scale 0-1023 to 0-255Put 0,f_pres_1,1 'send finger pressure to XportReturn

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Lantronix Xport

• Ethernet-to-serial converter• Can operate in TCP or

UDP modes• Web-based configuration

• Comfile “dongle” allows easy DB9 attachement

• Xport ($54), dongle ($8)• http://www.comfiletech.com

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CUBLOC Pros/Cons

Cons:

• More expensive than PIC/AVR, but less than BS

• Not very popular yet

Pros:

• Easy to program/use

• Many interfaces (A/D, PWM, I2C)

• Great vendor documentaton

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“Touch” Maquette

• To “touch someone” over the Internet

• R/C servo driving plastic finger

• Force-sensitive resistor on tip

• CUBLOC 220, Xport, Pololu Serial Servo controller

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MAKE Magazine Controller• Just came out ($149 for board)• 30 I/O lines• 8 A/D (up to 3.3V)• 8 “high current” motor driver outs• Ethernet/USB/I2C• Atmel AT91SAM7X256 based / 48

MIPS • C programmed• Connect to Max/MSP via Open

Sound Control (OSC)

• http://www.makingthings.com/makecontrollerkit/

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The Alternative: PC Parallel Ports

• 12 digital outputs

• 5 digital inputs

• 8 grounds

• Data pins (Dx) may also be inputs in bi-directional ports, giving 13 inputs

data = _inp(atoi(888)); /* read port 0x378 data pins */

_outp(atoi(888),atoi(data)); /* write port 0x378 data pins */

http://www.logix4u.net/parallelport1.htm

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PC w. Serial/USB Interfaces

• The Serializer ($139.95)• 16 Digital I/Os• 5 Analog inputs• 2 x 4A DC motor drivers• 2 RC Servo controllers• I2C Interface• .NET/C# programmable

• http://www.roboticsconnection.com/catalog/item/1767486/2337356.htm

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Microcontrollers you should know about

Thomas Edwards

http://www.t11s.com