Arduino Josh Villbrandt February 4, 2012

Digital Circuits Analog versus digital – What’s the difference? – How to represent an analog signal in a computer? – How to measure an analog signal? voltage divider analog to digital converter (ADC) Combinational logic – logic gates (built from transistors) AND/NAND, OR/XOR, NOR/XNOR Add gates together to make functional blocks – Add, subtract, multiply, divide, mux, demux Sequential logic – SR-latch – Basis for “memory”

Microcontrollers Combines commonly used functional blocks together – Arithmetic Logic Unit (ALU) – CPU register Provides an instruction set – Fetch, decode, execute – This happens each clock cycle

ATmega328 8 bit microcontroller at 16MHz Memory – 32KB Flash (bootloader and program storage) – 2KB SRAM (run-time “memory”) – 1KB EEPROM (program controlled permanent storage; like a hard drive) Features – Two 8-bit timers and one 16-bit timer – 14 digital pins (input or output) 2 pins can be used for TTL (transistor-transitor logic) serial – universal synchronous/asynchronous receiver/transmitter (USART or UART) – Can use all pins as “software” serial – Easily converted to RS-232 (-25V to -3V and 3V to 25V instead of 0V and 5V) 6 pins can be used for 8-bit Pulse Width Modulation (PWM) 4 pins can be used for Serial Peripheral Interface (SPI) – Fast, synchronous, short distances Can enable an internal pull-up resistor on each line – 6 (or 8) analog input pins (10 bit) 2 pins can be used for two wire interface (TWI) including Inter-Integrated Circuit communication (I 2 C) – Multi-master, multi-slave, up to 128 devices on one bus, generally low speed

Arduino An ATmega328 microcontroller wrapped with some convenience circuits – FTDI converts TTL serial to USB – Power regulation, USB overcurrent protection – Standardized form factor means people can build and share daughter boards (“shields”) Motor shield Bluetooth, wifi, or GSM shield Proto shield – LED on pin 13 – Reset button

More Info General microcontroller explanation from semiconductors and up – design/135-how-microcontrollers- work.html?showall=&limitstart= design/135-how-microcontrollers- work.html?showall=&limitstart= Arduino UNO spec page with ATmega328 datasheet: –