Transcript AVR - UCCS
AVR Modern RISC architecture: Compact and FAST. Tuned for high level languages. Consistent architecture across entire line. Small AVR are subsets of larger chips: Same hardware and code works across all chips. I/O structure reduces need for external components. Flash based, ultra trivial downloading of code. AVR RISC Architecture Single Cycle Instructions: 8mhz = 8mips. Large register file (32). Every register an accumulator. 3 index register pairs Register & IO are mapped in SRAM space. Typical Hardware Support Internal or External Oscillator/Clock Brown Out Detector One or more timers Two or more PWM One or more USART I2C Real time clock 10bit ADC Analog Comparator External interrupts Pulse timing capture EEPROM USB/CAN/RF Tools Atmel Studio: IDE & Simulator/debugger. BASCOM: Basic compiler & IDE with programmer. GNU C compiler (free, very high quality). Third party C compilers vary from cheap to very expensive. FLASH programmers are trivial to make. Availability & Price www.digikey.com has everything (single unit price): Attiny26 (2k, ADC, USI, 2 PWM, 2 ports) $2.58 ATmega16 (16k, ADC, etc, 4 ports) $7.74 ATmega128 (128k, 6 ports, oodles of stuff) $16.34 STK500 (development board) $79 ICE200 (In circuit emulator) $100 ATAVRISP (serial programmer) $29 I/O Example: simple switch No external parts Input Example: Trinary Input Three states with one input. Useful way to expand IO. Switch internal resistor on/off to determine state of pin. Off: If input high, then J1-2. On: if low, then J2-3. On: If high, then no jumper. Input example: Photo-detector Schmitt trigger inputs on all lines. No additional signal conditioning needed. Stable, well defined trip points. Basic circuit works well for Quadrature encoders. Input Example: Variable Input Useful for parts without ADC. Set pin to output, low to discharge capacitor. Set pin to input, no pull-up. Increment counter until input reads 1. Linear conversion. Case Studies BASCOM based multi-tasking Minisumo code in less than 2k Dilbert II written with GCC in less than 6k Gyrobot written with GCC in less than 6k LCD user interface PID based motion control Sensor tasks managing tilt, gyro and wheel encoders R/C Tether uses variable input (PC Joystick) Resources www.barello.net/ARC www.barello.net/Papers www.avrfreaks.net www.mcselec.com/download_avr www.atmel.com/ Cool projects & pages http://www.mysunrise.ch/users/pfleury/index.html http://instruct1.cit.cornell.edu/courses/ee476/ www.barello.net/Robots www.egnite.de (ethernet & web software) www.avrfreaks.net (Academy tab, must register)