Intro to AVR ATtiny2313

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Intro to AVR ATtiny2313

• CS423
• Dick Steflik

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AVR ATtiny2313
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2313 Features

• RISC, 120 instructions, most executable in one
  clock cycle, 32x8 general purpose registers, up
  to 20 MIPS at 20 Mhz
• Memory - 2Kbytes Flash, 128 Bytes EEPROM, 128
  bytes SRAM
• Peripherals Features 1-8bit timer, 1- 16 bit
  timer, 4- PWM channels, On-chip analog
  comparitor, watchdog timer, Universal Serial
  Interface, Full Duplex USART
• 18 programmable I/O lines
• Operating Voltage 2.7 5.5VDC
• In System Programmable via SPI (Serial Peripheral
  Interface)?

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Basic Pin Descriptions

• VCC Digital Supply Voltage
• Gnd ground
• Port A (PA2..PA0) 3 bit, bi-directional I/O
  with selectable internal pullups
• Port B (PB7..PB0) 8 bit, bi-directional I/O
  with selectable internal pullups
• Port D (PD6-PD0) - 7 bit, bi-directional I/O with
  selectable internal pullups
• Reset system reset active low
• XTAL1 external crystal input (alt. PA0)?
• XTAL2 external crystal output (alt. PA1)?

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Serial Peripheral Interface Bus

• SPI is used by all Atmel microcontrollers for
  loading the flash program memory (many other OEMs
  also)?
• Easily implemented in hardware
• Faster than other methods (I2C, SMBUS)?
• Master-slave methodology
• Half or Full Duplex operation

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SPI with 2 slaves
SPI Master
SPI Slave 1
SCLK
SCLK
MOSI
MOSI
MISO
MISO
SS1
SS
SS2
SPI Slave 2
SCLK
MOSI
MISO
SS
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AVR Programming
AVR Programmer
ATtiny2313
PC
VCC (20)?
VCC
SCLK (19)?
SCLK
MOSI
MOSI (17)?
AVRDUDE
MISO
MISO (18)?
PPT RS232 USB
RESET (1)?
GND
GND (10)?
GND
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API Applications

• Flash, EEPROM, MMC and SD cards
• Sensors
• Temperature
• Pressure (touch screens)?
• LCD Panels
• Communications (802.15 (ZigBee), CAN,
  Ethernet....)?
• Control D/A, A/D, Digital Pots, position
  encoders

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/ Blinker Demo / / Include useful pre-defined
functions / include ltavr/interrupt.hgt //
Defines pins, ports, etc to make programs easier
to read define F_CPU 100000UL // Sets up
the default speed for delay.h include
ltutil/delay.hgt int main() DDRD _BV(PD4)
/ enable output on port D, pin 4 /
while(1) PORTD _BV(PD4)
_delay_ms(1000) PORTD _BV(PD4)
_delay_ms(1000) return(0)
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Interrupts
1 0x0000 Reset External Pin, POR,
BOR,Watchdog Reset 2 0x0001 INT0 External
Interrupt Request 0 3 0x0002 INT1 External
Interrupt Request 1 4 0x0003 TIMER1
CAPT Timer/Counter1 Capture Event 5 0x0004 TIMER
1 COMPA Timer/Counter1 Compare Match
A 6 0x0005 TIMER1 OVF Timer/Counter1
Overflow 7 0x0006 TIMER0 OVF Timer/Counter0
Overflow 8 0x0007 USART0,RX USART0 Receive
complete 9 0x0008 USART0 UDRE USART0 Data
Register Empty 10 0x0009 USART0 RX USART0
Transmit Complete 11 0x000A ANALOG COMP Analog
Comparitor 12 0x000B PCINT Pin Change
Interrupt 13 0x000C TIMER1 COMPB Timer/Counter1
Compare Match B 14 0x000D TIMER0
COMPA Timer/Counter0 Compare Match
A 15 0x000E TIMER0 COMPB Timer/Counter0 Compare
Match B 16 0x000F USI START USI Start
Condition 17 0x0010 USI OVERFLOW USI
Overflow 18 0x0011 EE READY EEPROM
Ready 19 0x0012 WDT OVERFLOW Watchdog Timer
Overflow
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ISR Macro

• include ltavr/interrupt.hgt
• Defines the beginning of your Interrupt Servicing
  Routine
• Places the starting address of the ISR code into
  the interrupt vector

ISR(SIG_INT0)? cli() //disable interrupts
. . .
sei() // enable interrupts places address
of the body if the ISR into 0x0001
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Programmable Interrupts

• INT0 - Pin 6
• INT1 Pin 7
• PCINT Pins 12-19
• PCMSK Pin Change Mask Register
• Which pins contribute to the pin change interrupt
• 4 different pin changes can be detected
• Pin goes low
• Any logical change
• Falling edge
• Rising edge

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Interrupt Sense Control
Interrupt 1 Sense Control ISC11 ISC10 Description
0 0 Low level on INT1 0 1 Any
logical change on INT1 1 0 Falling edge
on INT1 1 1 Rising Edge on INT1
Interrupt 0 Sense Control ISC01 ISC00 Description
0 0 Low level on INT0 0 1 Any
logical change on INT0 1 0 Falling edge
on INT0 1 1 Rising Edge on INT0
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MCU Control Register

• Defines which of the four states will activate
  the interrupt

ex. MCUCR (1ltltISC01) (1ltltISC00)?
Interrupt on pin INT0 falling edge
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Example
include ltavr/interrupt.hgt int
main(void)? // set Pin 6 (PD02) as the
interrupt pin PCMSK (1ltltPIND2) //
interrupt on INT0 falling edge MCUCR
(1ltltISC01) (1 ltlt ISC00) // turn on
interrupts GIMSK (1ltltINT0) // wait for
interrupt while (1) ...