Programmers For AVR Serial & Parallel
Programming Hardware for AVR’s
As hobbyist we always search for some good & cost effective programmer hardware for our specific microcontroller. Here i am trying to describe how to make some serial & parallel port based programmer that supports standered development tools like WinAVR, PonyProg etc.
- Simple serial programmer (PonyProg compatible)
- Serial Programmer (WinAVR compatible)
- Parallel Port BSD Prog
Parallel Port Programmer
First let us discuss Parallel Port BSD Programmer. Originally from http://www.bsdhome.com/avrdude/. This programmer is very easy to make and as easy to use. This is a SPI based programmer, Serial peripheral Interface facility present in AVR series is very useful for programming the controller. Pins used on AVR is MOSI, MISO, SCK, RESET. Few resisters and thats it. Be careful with resisters do not skip any of them. Here is the circuit diagram.
Parallel Port PinOut
This programmer is compatible to WinAVR. In Makefile mention programmer as “bsd” and port as lpt1.
Note- To use this programmer in WinAVR you have to install drivers because Windows XP do not allow direct access to LPT port. Goto WinAVR install directory in your Windows Drive (Usually C:/), goto bin directory there you will find a batch file named as install_giveio.bat run that file. This will install LPT driver. Now you are done to use this bsd programmer with WinAVR.
Serial PORT Programmer Compatible to PONYPROG
Pony Prog Interface Setup for Programmer
Another Serial Port Programmer (PonySer)
PonyProg Interface setup for This Programmer
NOTE
This programmer is directly compatible to both PonyProg as well as WinAVR. In WinAVR you can use this programmer by specifying programmer as “ponyser” while cofiguring MAKEFILE.
devesh@electroons.com
Using External Interrupt in AVR
External Interrupts in AVR ATmega16/32/8
ATmega16/32 has Three pins which can be used to trigger external hardware interrupt to the controller. While ATmega8 has two external interrupt in it.
As ATmega16 & ATmega32 are pinwise compatible it has facility for external hardware interrupt at these pins.
INT0 – External Interrupt 0 – PIN 16/PORTD2
INT1 – External Interrupt 1 – PIN 17/PORTD3
INT2 – External Interrupt 2 – PIN 3/PORTB2
Suppose we have a task to blink a led whwnever a high to low edge is detected on the corresponding External Interrupt Pin. So when i write the code for that purpose it is said that i am writing an external interrupt service routine or interrupt handeller.
Here is the circuit diagrm for the task…
Below is a description of all the registers related to the interrupts…
1. We must set I (Interrupt) Flag high in Status register taht is SREG to use any kind of interrupts. This flag can be set by software using instruction like SEI or CLI in asm but in ‘C’ we can directly call functions like “sei()” to set I flag and “cli()” to reset I flag.
2. 6th bit of GICR taht is General Interrupt Control Register must keep high to use external interrupt 0 in your application. INT0 bit can be set to one by executing following statment.
GICR=(1<<INT0); // similarly for INT1 or INT2
3. Another very important register is MCUCR (MCU control register). here is a short description of how it affects external interrupt operation.
ISC01 ISC00 Description
0 0 Low level of INT0 generates an interrupt
0 1 Any logical change on INT0 generate
1 0 Falling edge of INT0 generates interrupt
1 1 Rising edge of INT0 generates interrupt]
Similar kind of bits are there for INT1 and INT2 in corresponding registers.
Here is the code in WinAVR to handle a external interrupt request.
#include<avr/io.h>
#include<avr/interrupt.h> // header that defines addresses for INT vect
#include<util/delay.h>
#include<compat/deprecated.h>
int main(void)
{
DDRD=0x00;
DDRA=0xFF;
PORTD=0xFF; // PIN INT0 initially pulled high
PORTA=0x00; // LED initially Off
sei(); // Interrupt flag set
GICR=1<<INT0; // INT0 enabled
sbi(MCUCR,1); // falling edge at INT0 generates interrupt
cbi(MCUCR,0);
while(1==1);
return 0 ;
}
SIGNAL( SIG_INTERRUPT0 ) // SIGNAL is a macro for interrupts
{
PORTA=0xA0;
_delay_ms(200);
PORTA=0x50;
_delay_ms(200);
PORTA=0x00;
}
Similar kind of code can be written for INT1 or INT2. Whatever you want to do on interrupt call just write it inside SIGNAL(int vector){} and that’s it.
Contact-
devesh samaiya
devesh@electroons.compre
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