Hands On AVR: Difference between revisions
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* download this make file and check | * download this make and save it to the same location as the source file is in. then open the Makefile and check the following: | ||
** TARGET: i called the source file "led.c", thus in the makefile the TARGET has to be named "led" (without extension). | ** TARGET: i called the source file "led.c", thus in the makefile the TARGET has to be named "led" (without extension). | ||
** AVRDUDE_PROGRAMMER: here "avrisp" is set, because we're using arduino. other programmers can be defined, if you are for example using the "AVR Pocket programmer" set | ** AVRDUDE_PROGRAMMER: here "avrisp" is set, because we're using arduino. | ||
Note: other programmers can be defined, if you are for example using the "AVR Pocket programmer", AVRDUDE_PROGRAMMER must be set to "usbtiny", for "AVRISP mkII", set it to 'stk500'. all programmers can be listed with the command <code>avrdude -c ?</code> | |||
* save the Makefile in the same folder as the source file is in. | * save the Makefile in the same folder as the source file is in. | ||
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**download hex file to AVR: <code>make program</code> | **download hex file to AVR: <code>make program</code> | ||
**at this stage the LED should already blink, but too slow, because the fuse bits are not set correctly yet. | **at this stage the LED should already blink, but too slow, because the fuse bits are not set correctly yet. | ||
We have to change the fuse bits. | |||
* Windows: <code>avrdude -P COM*** -c avrisp -p t13 -U lfuse:w:0x7a:m -U hfuse:w:0xff:m</code> (***select appropriate usb device, can be COM1, COM2, etc.) | |||
* Linux: <code>avrdude -P /dev/ttyUSB*** -c avrisp -p t13 -U lfuse:w:0x7a:m -U hfuse:w:0xff:m</code> (***select appropriate usb device) | |||
* enjoy the blinking LED! | * enjoy the blinking LED! |
Revision as of 06:06, 16 February 2012
Overview
This wiki page is dedicated to AVR development with focus on the ATtiny13.
Memory
The ATtiny13 has two main memories:
Program memory is 1K Bytes. It's organized as 512x16 Bits, because all AVR instructions are 16 or 32 bits wide.
Data memory is 64 bytes of SRAM (internal memory) + 64 I/O Registers + 32 general purpose registers.
Furthermore there's electrically erasable programmable read-only memory (EEPROM) of 64 Bytes. Single bytes can be read and written.
I/O Ports
Individual I/O ports can be set as input or output. Each output can deliver 40mA.
The ATtiny13 has 6 I/O pins named: PB0, PB1, PB2, PB3, PB4 and PB5. Generally AVR ports are named Pxn, x is the letter of the port, n is the pin number.
All pins of PORTB of the attiny13 can be configured with only three registers:
- Data Register - PORTB - write values to port PBx / set internal pull-up of PBx
- Data Direction Register – DDRB - set PBx as input (0) or output (1).
- Port Input Pins – PINB - read values at port PBx
Notes:
- If PORTxn is written logic one when the pin is configured as an input pin, the pull-up resistor is activated.
- The pin numbers don't correspond to the acutal hardware pin numbers, for example PB0 is located at hardware pin 5.
- All ports have also alternate functions (ADC, PWM, ..).
ArduinoISP
Arduino can be used as an In-system programming (ISP) interface for the ATtiny and ATmega microcontrollers.
Here are step-by-step instructions on how to program an attiny13 with an LED blinking program:
- On the Arduino, the ArduinoISP code must be running. Open the Arduino IDE -> examples -> ArduinoISP and write.
- Build the circuit as shown above. Pins are documented in the source code. Use a 470Ω resistor between PB4 (that's pin 3 on the attiny13) and the LED.
- Install AVR toolchain: Windows, Mac
- Save the following code to a file named "led.c" and save it in a new folder somewhere:
/*
hello, LED!
attiny13 Pins:
1: RESET (Arduino 10)
2: NC (not connected)
3: R (470Ω) to LED to GND
4: GND (Arduino Gnd)
5: MOSI (Arduino 11)
6: MISO (Arduino 12)
7: SCK (Arduino 13)
8: VCC (Arduino 5V)
*/
#define F_CPU 9600000 // Define software reference clock for delay duration
#include <avr/io.h>
#include <util/delay.h>
#define LED PB4 // Define led output on PB4
uint16_t d; // delay variable
/**
* delay
*
* @param ms duration in milliseconds
*
*/
void delay_ms(uint16_t ms)
{
for (uint16_t i = 0 ; i < ms ; i++) {
_delay_ms (1); // Loop delay
}
}
int main()
{
d = 250; // delay time in ms
DDRB |= (1 << LED); // Set direction to output for LED
for (;;) { // forever
PORTB ^= (1 << LED);
delay_ms(d);
}
return 0;
}
- download this make and save it to the same location as the source file is in. then open the Makefile and check the following:
- TARGET: i called the source file "led.c", thus in the makefile the TARGET has to be named "led" (without extension).
- AVRDUDE_PROGRAMMER: here "avrisp" is set, because we're using arduino.
Note: other programmers can be defined, if you are for example using the "AVR Pocket programmer", AVRDUDE_PROGRAMMER must be set to "usbtiny", for "AVRISP mkII", set it to 'stk500'. all programmers can be listed with the command avrdude -c ?
- save the Makefile in the same folder as the source file is in.
- run these commands from the cmd (windows) or shell (linux):
- to check, if we are using the correct compiler:
avr-gcc --version
(this should give you something like "avr-gcc (WinAVR 20100110) 4.3.3") - make hex file:
make all
- download hex file to AVR:
make program
- at this stage the LED should already blink, but too slow, because the fuse bits are not set correctly yet.
- to check, if we are using the correct compiler:
We have to change the fuse bits.
- Windows:
avrdude -P COM*** -c avrisp -p t13 -U lfuse:w:0x7a:m -U hfuse:w:0xff:m
(***select appropriate usb device, can be COM1, COM2, etc.) - Linux:
avrdude -P /dev/ttyUSB*** -c avrisp -p t13 -U lfuse:w:0x7a:m -U hfuse:w:0xff:m
(***select appropriate usb device)
- enjoy the blinking LED!
High Voltage Fuse Resetter
If the fusebits are messed up, the AVR can be factory resetted. This can be done with "high-voltage serial programming". Here is a excellent project to reset attiny13/25/45/85 chips: hvsp fuse resetter
tips:
- The schema on the website seems to have bugs, i fixed them, check my copy File:Hvsp-fuse-resetter-schema.pdf.
- The 7x4 LED module can be found on ebay. If the display doesn't work, you probably have to comment out "#define _REVERSE" in the code, this switches common anode/common cathode of the display.
AVR
more on AVR soon.