Thursday, July 23, 2009
Monday, July 20, 2009
Controlling 3 Stepper Motors with the 12 way Interface
source: http://www.southwest.com.au/~jfuller/
This interface is designed for use with a three axis robot arm based on stepper motors out of 5 1/4" drives. The circuit uses two ULN2803 'drivers' controlled by logic ICs to allow mutliple lines to be controlled at the same time. (Logic circuit design by Ian Threlfo). How it Works: Click here for an explanation of the circuit logic.
This is also the first interface bearing the Educational Computing Association of Western Australia (ECAWA) logo, indicating it has been developed by the ECAWA Robotics Special Interest Group.
Logic Design
PCB
Component Overlay
Parts List
2 x 4081 AND gate
2 x 4030 NOR gate
2 x ULN2803 Driver
1 x 74LS244 buffer
12 x 560 ohm resistor
12 x 100Kohm resistor
1 x 10Kohm resistor
1 x 47 uF electrolytic capacitor
1 x 2.1mm power socket
1 x DB25 PCB mount, right angle socket
1 x serial cable (male to male)
1 x 1 amp bridge rectifier
1 x 7805 voltage regulator
1 x 7812 voltage regulator
12 x 3mm red LEDs
2 x 0.01 uF greencap capacitors
1 x PCB
Wednesday, July 15, 2009
Low Speed AVR Oscilloscope
This project by Vassilis Serasidis. You can fing his original page at http://www.serasidis.gr/circuits/AVR_oscilloscope/avr_oscilloscope.htm
The maximum signal speed who can show up this oscilloscope is 5 kHz in square signal. For other signals (sine or triangle) the frequency is lower ( almost 1 kHz) for having clear view of the signal.
| Features | ||
|
The maximum signal speed who can show up this oscilloscope is 5 kHz in square signal. For other signals (sine or triangle) the frequency is lower ( almost 1 kHz) for having clear view of the signal.
Below is the schematic.
Description
The operating voltage of the circuit is 12V DC. By this voltage, the power supply is producing 2 voltages. +8.2V for IC1 and +5V for IC2 and IC3. This circuit can measure from +2.5V to -2.5V or from 0 to +5V dependent by S1 position (AC or DC input). By using probe with 1:10 division you can measure almost 10 times higher voltages. Moreover, with S2 you can make an extra division by 2 the input voltage.
Programming The ATmega32
Burn the ATmega32 with AVR_oscilloscope.hex and select external crystal at the fuses section.
After that, you Must disable the JTAG interface from your ATmega32 microController. If you don't do that, the mega32 will show you the initial screen and when it go to the oscilloscope screen it will restart immediately to the initial screen and it will stay there for ever.
Calibrations
The only 2 things you have to calibrate is the LCD contrast trimmer P2 and the P1, to move the beam at the center of the LCD. To do that, apply only the power supply to the circuit and adjust the P2 up to the point you will see clear the appeared pixels on the screen. Then, adjust the P1 up to the point the beam is moved at the middle of the LCD (at the horizontal line of the cross).
Usage
You can move the beam up or down the screen by pressing the buttons S8 or S4 correspondingly to measure the voltage of the signal. 1 volt is taking up 1 square height. With S7 and S3 you can increase or decrease the measurement speed. This oscilloscope has an automatic trigger. That means, if you have a continuous signal (ex a triagle waveform) the auto trigger will work perfect. If your signal is not stable (ex a serial transmittion) you can freeze the screen by pressing S6 switch. At his case you can get a snapshoot of your measurment signal. By the time you release the S6, the snapshoot will end.
PCB (101x160mm) and components placing
| | V1.01 Download the source code and the hex file of AVR oscilloscope. |
| | V1.00 Download the source code, hex, schematic and PCB of AVR oscilloscope. |
| | Software to make your own 128x64 pixel logos for graphical LCDs . |
So, what do you think guy's? isn't this is great projects? thanks to Mr Vassilis Serasidis for this great projects.
If you have any doubt, please go to http://www.serasidis.gr/circuits/AVR_oscilloscope/avr_oscilloscope.htm
Tuesday, July 14, 2009
ATmega 32 & DS1307 Digital Clock
This projects called Digital Clock used ATmega 32 and RTC DS 1307.
FEATURES OF DS1307
1. Real time clock counts seconds,minutes,hours, date of month,moth, day of week and year with leap year compensation valid up to 2100.
2. 56 byte nonvolatile RAM for general data storage
3. 2-wrire interface (I2C)
4. Automatic power fail detect
5. Comsumes less than 500 nA for battery back-up at 25′C
With this features, DS 1307 is great rtc can we use to build a perfect digital clock.
Here is the schematic for DS1307 Connection to ATmega 32:
FEATURES OF DS13071. Real time clock counts seconds,minutes,hours, date of month,moth, day of week and year with leap year compensation valid up to 2100.
2. 56 byte nonvolatile RAM for general data storage
3. 2-wrire interface (I2C)
4. Automatic power fail detect
5. Comsumes less than 500 nA for battery back-up at 25′C
With this features, DS 1307 is great rtc can we use to build a perfect digital clock.
Here is the schematic for DS1307 Connection to ATmega 32:
The clock display used LCD, C Port for LCD, B.0 Port for SCL and B.1 Port for SDA Port 0.
Below is the sourcecode to read RTC DS1307 used CodeVision AVR Evaluation 2.03.9
Source 1 :
**************************************************************
#include
// I2C Bus functions
#asm
.equ __i2c_port=0×18 ;PORTB
.equ __sda_bit=0
.equ __scl_bit=1
#endasm
#include
// Alphanumeric LCD Module functions
#asm
.equ __lcd_port=0×15 ;PORTC
#endasm
#include
// Standard Input/Output functions
#include
#include
#define ADDA_ADDR 0×90
#define EEPROM_ADDR 0xA0
#define RTC_ADDR 0xD0
unsigned char data_rtc[8];
unsigned char kata1[16];
unsigned char kata2[16];
unsigned char kata3[16];
unsigned char kata4[16];
unsigned char kata5[16];
unsigned char kata6[16];
// Declare your global variables here
unsigned char bcd2dec(unsigned char input){
unsigned char tmp_data, tmp1;
tmp_data = input;
tmp1 = tmp_data % 16;
if (tmp_data > 15) tmp_data = tmp_data / 16;
else tmp_data = 0;
tmp_data = (tmp_data * 10)+tmp1;
return tmp_data;
}
void read_rtc(void){
unsigned char i, tmp_data;
i2c_start();
i2c_write(RTC_ADDR);
i2c_write(0);
i2c_stop();
i2c_start();
i2c_write(RTC_ADDR | 1);
for (i=0; i<6; tmp_data =" bcd2dec(i2c_read(1));" tmp_data =" bcd2dec(i2c_read(0));">
unsigned char dec2bcd(unsigned char input){
unsigned char tmp_data;
if (input > 9) tmp_data = ((input / 10)*16) + (input % 10);
else
tmp_data = input;
return tmp_data;
}
void write_rtc(unsigned char alamat, unsigned char data){
i2c_start();
i2c_write(RTC_ADDR);
i2c_write(alamat);
if (alamat <>
unsigned char read_nvram(unsigned char alamat){
unsigned char tmp_data;
i2c_start();
i2c_write(RTC_ADDR);
i2c_write(alamat);
i2c_stop();
i2c_start();
i2c_write(RTC_ADDR | 1);
tmp_data = i2c_read(0);
i2c_stop();
return tmp_data;
}
unsigned char read_EEPROM(unsigned char alamat){
unsigned char data;
i2c_start();
i2c_write(EEPROM_ADDR);
i2c_write(alamat);
i2c_start();
i2c_write(EEPROM_ADDR | 1);
data = i2c_read(0);
i2c_stop();
return data;
}
void write_EEPROM(unsigned char alamat, unsigned char nilai){
i2c_start();
i2c_write(EEPROM_ADDR);
i2c_write(alamat);
i2c_write(nilai);
i2c_stop();
delay_ms(10);}
void main(void)
{
// USART initialization
// Communication Parameters: 8 Data, 1 Stop, No Parity
// USART Receiver: On
// USART Transmitter: On
// USART Mode: Asynchronous
// USART Baud rate: 9600
UCSRA=0×00;
UCSRB=0×18;
UCSRC=0×86;
UBRRH=0×00;
UBRRL=0×47;
// I2C Bus initialization
i2c_init();
// LCD module initialization
lcd_init(16);
putchar(’p');
while (1)
{
read_rtc();
//0123456789ABCDEF
sprintf(kata1,”%2d:”,data_rtc[2],);
sprintf(kata2,”%2d:”,data_rtc[1],);
sprintf(kata3,”%2d”,data_rtc[0],);
sprintf(kata4,”%2d-”,data_rtc[4],);
sprintf(kata5,”%2d-”,data_rtc[5],);
sprintf(kata6,”%2d”,data_rtc[6],);
lcd_clear();
lcd_gotoxy(3,0);lcd_puts(kata1);
lcd_gotoxy(6,0);lcd_puts(kata2);
lcd_gotoxy(9,0);lcd_puts(kata3);
lcd_gotoxy(3,1);lcd_puts(kata4);
lcd_gotoxy(6,1);lcd_puts(kata5);
lcd_gotoxy(9,1);lcd_puts(kata6);
delay_ms(100);
}
}
Source 2 :
**************************************************************
#include
// I2C Bus functions
#asm
.equ __i2c_port=0×18 ;PORTB
.equ __sda_bit=0
.equ __scl_bit=1
#endasm
#include
// Alphanumeric LCD Module functions
#asm
.equ __lcd_port=0×15 ;PORTC
#endasm
#include
// Standard Input/Output functions
#include
#include
#define ADDA_ADDR 0×90
#define EEPROM_ADDR 0xA0
#define RTC_ADDR 0xD0
unsigned char data_rtc[8];
unsigned char data_t[16];
// Declare your global variables here
unsigned char bcd2dec(unsigned char input){
unsigned char tmp_data, tmp1;
tmp_data = input;
tmp1 = tmp_data % 16;
if (tmp_data > 15) tmp_data = tmp_data / 16;
else tmp_data = 0;
tmp_data = (tmp_data * 10)+tmp1;
return tmp_data;
}
void read_rtc(void){
unsigned char i, tmp_data,y;
i2c_start();
i2c_write(RTC_ADDR);
i2c_write(0);
i2c_stop();
i2c_start();
i2c_write(RTC_ADDR | 1);
for (i=0; i<6; tmp_data =" bcd2dec(i2c_read(1));" tmp_data =" bcd2dec(i2c_read(0));">
unsigned char dec2bcd(unsigned char input){
unsigned char tmp_data;
if (input > 9) tmp_data = ((input / 10)*16) + (input % 10);
else
tmp_data = input;
return tmp_data;
}
void write_rtc(unsigned char alamat, unsigned char data){
i2c_start();
i2c_write(RTC_ADDR);
i2c_write(alamat);
if (alamat <>
unsigned char read_nvram(unsigned char alamat){
unsigned char tmp_data;
i2c_start();
i2c_write(RTC_ADDR);
i2c_write(alamat);
i2c_stop();
i2c_start();
i2c_write(RTC_ADDR | 1);
tmp_data = i2c_read(0);
i2c_stop();
return tmp_data;
}
void main(void)
{
// USART initialization
// Communication Parameters: 8 Data, 1 Stop, No Parity
// USART Receiver: On
// USART Transmitter: On
// USART Mode: Asynchronous
// USART Baud rate: 9600
UCSRA=0×00;
UCSRB=0×18;
UCSRC=0×86;
UBRRH=0×00;
UBRRL=0×47;
// I2C Bus initialization
i2c_init();
// LCD module initialization
lcd_init(16);
while (1)
{
read_rtc();
//0123456789ABCDEF
data_t[0]=(data_rtc[2]/10)|0×30;
data_t[1]=(data_rtc[2]%10)|0×30;
data_t[2]=(data_rtc[1]/10)|0×30;
data_t[3]=(data_rtc[1]%10)|0×30;
data_t[4]=(data_rtc[0]/10)|0×30;
data_t[5]=(data_rtc[0]%10)|0×30;
data_t[6]=(data_rtc[4]/10)|0×30;
data_t[7]=(data_rtc[4]%10)|0×30;
data_t[8]=(data_rtc[5]/10)|0×30;
data_t[9]=(data_rtc[5]%10)|0×30;
data_t[10]=(data_rtc[6]/10)|0×30;
data_t[11]=(data_rtc[6]%10)|0×30;
data_t[12]=(data_rtc[3]/10)|0×30;
data_t[13]=(data_rtc[3]%10)|0×30;
lcd_clear();
lcd_gotoxy(3,0);lcd_putchar(data_t[0]);
lcd_gotoxy(4,0);lcd_putchar(data_t[1]);
lcd_gotoxy(5,0);lcd_putchar(’:');
lcd_gotoxy(6,0);lcd_putchar(data_t[2]);
lcd_gotoxy(7,0);lcd_putchar(data_t[3]);
lcd_gotoxy(8,0);lcd_putchar(’:');
lcd_gotoxy(9,0);lcd_putchar(data_t[4]);
lcd_gotoxy(10,0);lcd_putchar(data_t[5]);
lcd_gotoxy(0,1);lcd_putchar(data_t[12]);
lcd_gotoxy(1,1);lcd_putchar(data_t[13]);
lcd_gotoxy(3,1);lcd_putchar(data_t[6]);
lcd_gotoxy(4,1);lcd_putchar(data_t[7]);
lcd_gotoxy(5,1);lcd_putchar(’:');
lcd_gotoxy(6,1);lcd_putchar(data_t[8]);
lcd_gotoxy(7,1);lcd_putchar(data_t[9]);
lcd_gotoxy(8,1);lcd_putchar(’:');
lcd_gotoxy(9,1);lcd_putchar(’2′);
lcd_gotoxy(10,1);lcd_putchar(’0′);
lcd_gotoxy(11,1);lcd_putchar(data_t[10]);
lcd_gotoxy(12,1);lcd_putchar(data_t[11]);
delay_ms(200);
}
}
Tuesday, July 7, 2009
Humanoid: Albert Hubo
A robot called Robot Hubo is the creation of professor Jun Ho-Oh. Jun Ho-Oh from South Korea's Institute of Advanced Technology. This robotcan talk, walk and even smile because it have 66 motors, wow this is huge amount of motor for a humanoid. Albert Hubo run on Windows XP Platform with 4 foot 5 inches tall make this robot become a very interesting robot and the way it talk and moving is cool. See the video below, it's cool.
Below is the video from the Development of HUBO (KHR-3)
Great video to learn much about making the humanoid.
Saturday, July 4, 2009
AVR Basic Tutorial
This tutorial i take from http://www.8051projects.net by Ajay Bhargav.
Note: The tutorials will be in assembly language.
Lets Learn AVR - Step 1:
The first step in the development of any micrcontroller is to know about its architecture and instruction set. So i advice you all to keep a copy of instruction set and architecture manual. You can download them from the link below.
AVR Instruction Set (User Guide, 150 pages)
Architecture Manual or Datasheet for your AVR Microcontroller
The above document will help you to get familiar with the instruction set and to know about your AVR in a better way.
After this, we now have to decide the IDE on which you are going to work or write program for your AVR. I advice you to use AVR Studio 4 from Atmel Corporation, which is a free IDE for AVR and it has many features like programming, debugging etc.
You can get your free copy of AVR studio from link below.
AVR Studio 4.12 (build 460) (45 MB, updated 11/05) - Registration needed
AVR Studio 4.12 Service Pack 4 (build 498) (25 MB, updated 10/06) - No registration
AVR Studio 4.13 (build 528) (73 MB, updated 03/07) - Registration needed
So you can download any of the copy above as per your need more information about AVR studio can be obtained from
AVR Studio 4
All documents and IDE for writing program is ready.. only thing left is a programmer, with which we are going to program our AVR. As we know almost all AVR comes with ISP (In System Programmable) ports. So you don't need any special hardware to program your AVR. Please see the link below for ISP programmer for AVR.
Download PonyProg - serial device programmer
Interfacing Schematic:
Note: Do not forget to run the setup after installing PonyProg.
Setup Information:
In interface setup, select parallel and then from the drop down select AVR ISP I/O.
slect the LPT Port (parallel port) available on your PC. Then click ok!
To load Hex file:
Go to File-> Open Program (FLASH) file
then from the drop down where ".e2p" is show, select ".hex" and load your hex file.
AVR Tutorial - Step 2
Before programming AVR, first you need to know few important programming tips and AVR registers.
This include the definition file for ATmega8515, so that we can directly address the registers with their names.
All AVRs have 32 general purpose registers from R0 - R32.
R0-R15 registers have certain restrictions of use, i.e. they are not allowed to load immediate value.
e.g. LDI R15, $35
the above statement will give you an error, saying "Invalid Register"
Where as registers from R16-R32 can be used for this purpose i.e.
LDI R16,$35
is a valid statement.
You can move values from one register to other by using
MOV R15,R16
Not only the registers from R0 to R15 has restriction on LDI but also other commands where the use of R0-R16 is not allowed. usually all commands having immediate operands are not allowed.
For the ease of programming, you can also give names to the register like
There are some special registers like X,Y and Z for 16-Bit operations. They are used to read and write to XRAM. They are also used for reading from program memory like reading from a lookup table (we will discuss about them when we use them). These special registers are actually combination of two 8-bit General purpose registers. i.e. X is actually R26:R27, Y is R28:R29 and Z is R30:R31.
The lower byte of the 16-bit-adress is located in the lower register, the higher byte in the upper register. Both parts have their own names, e.g. the higher byte of Z is named as ZH (R31) and the lower Byte is ZL (R30). Similarly for X (XL and XH) and for Y (YL and YH). These names are defined in the standard header file for the chips (which we include while writing program). Dividing these 16-bit-pointer-names into two different bytes is done like follows:
where LABEL is address for any lookup table or any memory location.
Some important notes for using registers
Now coming to ports, The information about a specific port of a certain type of AVR can be easily obtained in the AVR Datasheet. Port names are defined in the include file of the CPU..
if you don't have an include file then you can define yourself as..
So if you are not able to find an include file you can use the .EQU directive to define ports and other registers.
Making port as i/p or o/p is purely dependent on data direction register called DDRx (DDRA for port A etc.) The DDxn bit in the DDRx Register selects the direction of this pin. If DDxn is written
logic one, Pxn is configured as an output pin. If DDxn is written logic zero, Pxn is configured
as an input pin.
for writing and reading data to Ports, PORTx registers are there. and to read from ports PINx registers are there.
for example..
writing to port
Reading from port
We are finished with the basics of AVR, lets try programming with simplest program. Blinking an LED!
Lets learn AVR Tutorial - Step 3
In this part of tutorial you will learn
Here is the summary of Load and store instructions that are used for dealing with SRAM of AVR Microcontroller
To read from Program memory we have special instructions like
Note: load from program memory instructions are not supported by all AVR architectures. Most of the architectures support LPM instruction which is hard coded to load R0 from location in Z. where as in some AVR this is also not implemented.
Now we are done with the instructions overview.. now lets practice them..
Program 1: Copy 10 Bytes memory block stored in Program memory(ROM) to Data memory (SRAM)
In the above code.. you can see while loading the address of program memory location, i multiplied it with 2, i.e. LDI ZH,High(2*Data)
The reason is, the program memory is organized in word manner i.e. two bytes for each command, So the address has to be multiplied by 2. You can try running these programs and see its working in the Simulator of AVR Studio.
Program 1: Find Greatest of 3 numbers Stored in program memory
Now you can try yourself writing some programs to make yourself more easy with load and store operations.
Here is the list of programs you can try out:
Note: The tutorials will be in assembly language.
Lets Learn AVR - Step 1:
The first step in the development of any micrcontroller is to know about its architecture and instruction set. So i advice you all to keep a copy of instruction set and architecture manual. You can download them from the link below.
AVR Instruction Set (User Guide, 150 pages)
Architecture Manual or Datasheet for your AVR Microcontroller
The above document will help you to get familiar with the instruction set and to know about your AVR in a better way.
After this, we now have to decide the IDE on which you are going to work or write program for your AVR. I advice you to use AVR Studio 4 from Atmel Corporation, which is a free IDE for AVR and it has many features like programming, debugging etc.
You can get your free copy of AVR studio from link below.
AVR Studio 4.12 (build 460) (45 MB, updated 11/05) - Registration needed
AVR Studio 4.12 Service Pack 4 (build 498) (25 MB, updated 10/06) - No registration
AVR Studio 4.13 (build 528) (73 MB, updated 03/07) - Registration needed
So you can download any of the copy above as per your need more information about AVR studio can be obtained from
AVR Studio 4
All documents and IDE for writing program is ready.. only thing left is a programmer, with which we are going to program our AVR. As we know almost all AVR comes with ISP (In System Programmable) ports. So you don't need any special hardware to program your AVR. Please see the link below for ISP programmer for AVR.
Download PonyProg - serial device programmer
Interfacing Schematic:
Note: Do not forget to run the setup after installing PonyProg.
Setup Information:
In interface setup, select parallel and then from the drop down select AVR ISP I/O.
slect the LPT Port (parallel port) available on your PC. Then click ok!
To load Hex file:
Go to File-> Open Program (FLASH) file
then from the drop down where ".e2p" is show, select ".hex" and load your hex file.
AVR Tutorial - Step 2
Note: The program i wrote is for ATMEGA8515 and there is not much difference in other AVRs except some has extra features.
Before programming AVR, first you need to know few important programming tips and AVR registers.
CODE:
.include "8515def.inc"
This include the definition file for ATmega8515, so that we can directly address the registers with their names.
All AVRs have 32 general purpose registers from R0 - R32.
R0-R15 registers have certain restrictions of use, i.e. they are not allowed to load immediate value.
e.g. LDI R15, $35
the above statement will give you an error, saying "Invalid Register"
Where as registers from R16-R32 can be used for this purpose i.e.
LDI R16,$35
is a valid statement.
You can move values from one register to other by using
MOV R15,R16
Not only the registers from R0 to R15 has restriction on LDI but also other commands where the use of R0-R16 is not allowed. usually all commands having immediate operands are not allowed.
For the ease of programming, you can also give names to the register like
CODE:
.def myregister = R16
There are some special registers like X,Y and Z for 16-Bit operations. They are used to read and write to XRAM. They are also used for reading from program memory like reading from a lookup table (we will discuss about them when we use them). These special registers are actually combination of two 8-bit General purpose registers. i.e. X is actually R26:R27, Y is R28:R29 and Z is R30:R31.
The lower byte of the 16-bit-adress is located in the lower register, the higher byte in the upper register. Both parts have their own names, e.g. the higher byte of Z is named as ZH (R31) and the lower Byte is ZL (R30). Similarly for X (XL and XH) and for Y (YL and YH). These names are defined in the standard header file for the chips (which we include while writing program). Dividing these 16-bit-pointer-names into two different bytes is done like follows:
CODE:
LDI YH,HIGH(LABEL) ; Set the MSB
LDI YL,LOW(LABEL) ; Set the LSB
LDI YL,LOW(LABEL) ; Set the LSB
where LABEL is address for any lookup table or any memory location.
Some important notes for using registers
- Define names for registers with the .DEF directive, never use them with their direct name Rx. This helps you making better use of registers and you will never confuse yourself while using them.
- If you need pointer access reserve R26 to R31 for that purpose.
- 16-bit-counter are best located R25:R24.
- If you need to read from the program memory, e.g. fixed tables, reserve Z (R31:R30) and R0 for that
purpose. - If you plan to have access to single bits within certain registers (e.g. for testing flags), use R16 to
R23 for that purpose
Now coming to ports, The information about a specific port of a certain type of AVR can be easily obtained in the AVR Datasheet. Port names are defined in the include file of the CPU..
if you don't have an include file then you can define yourself as..
CODE:
.equ PORTA = $1B ;incase of ATmega8515
So if you are not able to find an include file you can use the .EQU directive to define ports and other registers.
Making port as i/p or o/p is purely dependent on data direction register called DDRx (DDRA for port A etc.) The DDxn bit in the DDRx Register selects the direction of this pin. If DDxn is written
logic one, Pxn is configured as an output pin. If DDxn is written logic zero, Pxn is configured
as an input pin.
for writing and reading data to Ports, PORTx registers are there. and to read from ports PINx registers are there.
for example..
writing to port
CODE:
.def output = R16
LDI output, $FF
OUT DDRA, output ; making as o/p
LDI output, $00
OUT PORTA, output ; clear all PORTA pins
LDI output, $FF
OUT DDRA, output ; making as o/p
LDI output, $00
OUT PORTA, output ; clear all PORTA pins
Reading from port
CODE:
.def input = R17
LDI input, $00
OUT DDRA,input
IN input, PINA
LDI input, $00
OUT DDRA,input
IN input, PINA
We are finished with the basics of AVR, lets try programming with simplest program. Blinking an LED!
CODE:
.include "8515def.inc" ;Include file
RJMP MAIN ;Reset vector
MAIN:
ldi R16,low(RAMEND) ;Load stack with
out SPL,R16 ;RAMEND - highest value
ldi R16,high(RAMEND) ;of internal SRAM
out SPH,R16
SBI DDRA,0 ;Make PORTA Pin 0 as o/p
DO:
SBI PORTA,0 ;Set Pin 0 of PORTA
RCALL DELAY ;Wait for some time
CBI PORTA,0 ;Cleare Pin 0 of PORTA
RCALL DELAY ;Wait for some time
RJMP DO ;Forever loop!
DELAY: ;The delay routine
LDI R16,$20 ;Load some delay value
LOOP1:
SER R17 ;Make R17 as $FF
LOOP:
DEC R17 ;Decrement R17
BRNE LOOP ;Jump if not zero
DEC R16 ;Decrement R16
BRNE LOOP1 ;Jump if not zero
RET ;Return
Lets learn AVR Tutorial - Step 3
In this part of tutorial you will learn
- Reading from Program memory
- Reading from RAM
- Writing to RAM
- Practice programs
Here is the summary of Load and store instructions that are used for dealing with SRAM of AVR Microcontroller
- LD Rn,X/Y/Z
>either X or Y or Z register can be used
>this will load the value which is stored in memory location pointed by register X/Y/Z to the destination register Rn (can be R0, R1.. any etc) - LD Rn,X+/Y+/Z+
>This instruction will load the value which is stored in memory at location pointed by X/Y/Z registers and then increment the memory location by 1
>This is a post increment instruction - LD Rn, -X/-Y/-Z
>Load Rn with value stored at location pointed by pre-decrement of address stored in X/Y/Z - LDD Rn,Y/Z+displacement
>Load Rn with value at address Z or Y + displacement
>e.g. Z is 0x0090, Displacement is 0x10 so Rn will be loaded with value stored at 0x0090+0x10 = 0x0100 - ST X/Y/Z, Rn
>Store the value of Rn to location pointed by X or Y or Z - ST X+/Y+/Z+, Rn
>Store the value in Rn to location pointed by X or Y or Z and increment the address pointer - STD Y/Z+displacement, Rn
>Store the value in Rn to location pointed by Y or Z + Displacement - LDS Rn, SRAM_Address
>Load value from SRAM Address to the Rn register
>SRAM Address is the immediate value e.g. LDS R0,0x0100 - STS SRAM_Address, Rn
>Store Rn to immediate SRAM location
To read from Program memory we have special instructions like
- LPM
>Load form program memory, This instruction is used in most of the AVRs and its hard coded in the architecture.
>This instruction will load R0 with the address specified by register Z [This is hardcoded] - LPM Rn, Z
>Load Rn from program memory pointed by register Z
>This instruction is not supported by all AVRs e.g ATMega8515, AT90S8515 - LPM Rn,Z+
>Load Rn from program memory and increment the memory location pointed by Z
>This instruction is also not supported by all AVRs
Note: load from program memory instructions are not supported by all AVR architectures. Most of the architectures support LPM instruction which is hard coded to load R0 from location in Z. where as in some AVR this is also not implemented.
Now we are done with the instructions overview.. now lets practice them..
Program 1: Copy 10 Bytes memory block stored in Program memory(ROM) to Data memory (SRAM)
CODE:;This program is to copy memory block from Program
;memory to AVR RAM (10 Bytes)
.include "8515def.inc"
.org $0
.def Temp = R0 ;Temprary variable
.def count = R17 ;Byte Count
ldi ZH,HIGH(2*data) ;Load Z with address where
ldi ZL,LOW(2*data) ;our data is stored
ldi XL,$60 ;Load Destination RAM location
ldi XH,$0
ldi count,$A ;Load count 10 Bytes
again:
lpm ;Load value from program memory
inc ZL ;Increment memory location
st X+,Temp ;Store byte to the RAM location
dec count ;Decrement Count
brne again ;Check if all bytes moved
end:
rjmp end ;End of program
;Our data which we will copy from Program Memory to RAM
Data:
.db $10,$20,$30,$40,$50,$60,$70,$80,$90,$95
In the above code.. you can see while loading the address of program memory location, i multiplied it with 2, i.e. LDI ZH,High(2*Data)
The reason is, the program memory is organized in word manner i.e. two bytes for each command, So the address has to be multiplied by 2. You can try running these programs and see its working in the Simulator of AVR Studio.
Program 1: Find Greatest of 3 numbers Stored in program memory
CODE:;Program to find greatest of 3 numbers
;
;numbers are stored in ROM and the final
;result will be stored in a register
.include "8515def.inc"
.def num1 = r0 ;Location for First number
.def num2 = r1 ;Location for second number
.def answer = R2 ;location for Final answer
.org $0
ldi ZL, Low(2*Data) ;Load the program memory address
ldi ZH, High(2*data)
lpm ;Load first number
mov num2,num1 ;Move it to num2
inc ZL ;Increment the address
lpm ;Load second number
cp num1,num2 ;Compare them
brlt next ;Jump if num1 less than num2
mov num2,num1 ;If num1>num2 then move num1
next: ; to num2 location
inc ZL ;Increment the address
lpm ;Load the third number
cp num1,num2 ;Again compare
brlt final ;Check if num1 < num2
mov answer,num1 ;If No, then num1 is answer
final:
mov answer,num2 ;If Yes, then num2 is our answer
end:
rjmp end ;End of program
Data: ;Our 3 numbers
.db $23,$23,$14 ;Try changing them and see results
Now you can try yourself writing some programs to make yourself more easy with load and store operations.
Here is the list of programs you can try out:
- Swap two numbers stored in RAM
- Find Greatest of 5 numbers
- Copy memory block from RAM to RAM
- Sorting of 10 numbers
- Clear SRAM area from 0x60 to RAMEND
So here are the programs.. Please take a look!
Swap two numbers stored in RAMCODE:;Program to swap two numbers
.include "8515def.inc"
.def temp = R16 ;Temporary register
.def num1 = R17 ;Number one location
.def num2 = R18 ;Location for second number
.cseg
.org $0
ldi ZH,0x00 ;Assuming the two numbers are stored
ldi ZL,0x90 ;at location 0x0090 in RAM
ld num1,Z+ ;Load first number
ld num2,Z ;Load second number
mov temp,num1 ;copy num1 to temp
mov num1,num2 ;copy num2 to num1
mov num2,temp ;copy temp to num2
ldi ZL,0x90 ;load the RAM location back
st Z+,num1 ;store the first number
st Z, num2 ;store the second number
end:
rjmp end ;end of prog
Find Greatest of 5 numbersCODE:;Program to find greatest of 5 numbers
;
;numbers are stored in ROM and the final
;result will be stored in a register
.include "8515def.inc"
.def num1 = r0 ;Location for First number
.def num2 = r1 ;Location for second number
.def answer = R2 ;location for Final answer
.def count = r16 ;Count
.org $0
ldi ZL, Low(2*Data) ;Load the program memory address
ldi ZH, High(2*data)
ldi count,4 ;Load count
lpm ;Load first number
mov num2,num1 ;Move it to num2
adiw Z,1
again:
lpm ;Load second number
cp num1,num2 ;Compare them
brlt next ;Jump if num1
mov num2,num1 ;If num1>num2 then move num1
next: ; to num2 location
adiw Z,1 ;Increment the address
dec count ;are we done with all 5 numbers?
brne again ;if no then jump back
final:
mov answer,num2 ;If Yes, then num2 is our answer
end:
rjmp end ;End of program
;Try changing them and see results
Data: ;Our 5 numbers
.db $3,$23,$14,$50,$20,$0
;last zero is to aligh the bytes in word manner
;we have 5 numbers so i am padding with a 0 to make it
;even. if we dont't do this.. compiler will do it
;automatically to prevent misalignment.
Copy memory block from RAM to RAMCODE:;Program to copy a block of memory (10 Bytes)
; from one RAM location to another RAM location.
.include "8515def.inc"
.def temp = r0
.def count = r16
.org 0
ldi ZL,0x60 ;Lets fill the RAM with some numbers
ldi ZH,0x00 ;to copy, so we can check is it working
ldi count,10 ;Load count
fill:
st Z+,count ;Store value to RAM location
dec count
brne fill
ldi ZL,0x60 ;Load memory location to copy from
ldi ZH,0x00
ldi YL,0x90 ;Load destination memory location
ldi YH,0x00
ldi count,10 ;Load count
copy:
ld temp,Z+ ;Load value to temporary register
st Y+,temp ;Store it to location
dec count ;decrement counter
brne copy
end:
rjmp end ;End of program...
Sorting of 10 numbersCODE:;Program to sort 10 numbers
;in ascending order
;10 numbers are stored in ROM
;and sorted answer is stored in RAM
;at location 0x0060
.include "8515def.inc"
.def count1 = r17 ;First Count
.def count2 = r18 ;Second count
.def temp = r0 ;Temp reg for swap
.def num1 = r1 ;Num 1
.def num2 = r2 ;Num 2
.cseg ;Code segment starts
.org 0
ldi Zh,high(2*mydata) ;Load memory add where
ldi Zl,low(2*mydata) ;data is stored in ROM
ldi Yh,0x00 ;Destination location
ldi Yl,0x60 ;0x0060 in RAM
ldi count1,10 ;Load count
copy:
lpm ;Load from program mem
st Y+,temp ;Store it to RAM
adiw Z,1 ;Increment Z
dec count1 ;Decrement counter
brne copy ;copy all 10 bytes
ldi ZH,0x00 ;Load first pointer
ldi ZL,0x60
ldi count1,10 ;Load counter for it
sort:
mov YL,ZL ;Load second pointer
mov YH,ZH
adiw Y,1 ;Increment it
ld num1,Z ;load first number
mov count2,count1 ;load count2
subi count2,1 ;Count2 = Count1-1
breq end ;end if last num
again:
ld num2,Y ;Load second number
cp num1,num2 ;Compare them
brlo next ;Jump if num1
mov temp,num2
mov num2,num1 ;If num1>num2 then swap
mov num1,temp
st Z,num1 ;and store them on their
st Y,num2 ;respective locations
next:
adiw Y,1 ;Increment the address
dec count2 ;dec count2 for Y pointer
brne again ;check if count is zero
adiw Z,1 ;increment Z pointer
dec count1 ;Dec count1 for Z pointer
brne sort ;finish if zero
end:
rjmp end ;End of program
mydata:
.db $10,$90,$50,$20,$91,$23,$55,$62,$39,$80
Clear SRAM area from 0x60 to RAMENDCODE:;Program to clear RAM
;this program is for ATMega8515 So ram area is from
;0x60 to RAMEND
.include "8515def.inc"
.def temp = r16 ;Temporary variable
.def cnth = r25 ;Counter High byte
.def cntl = r24 ;Counter Low byte
.org 0
ldi cnth,0x02 ;Load count 0x200 to clear
ldi cntl,0x00 ;memory from 0x00 to 0x1FF
clr temp ;clear temp
ldi ZH,0x00 ;Load starting address of
ldi ZL,0x60 ;RAM 0x0060 in Z pointer
clrram:
st Z+,temp ;Store 0 in current Z location
sbiw cnth:cntl,1 ;Decrement the counter
brne clrram ;end if zero
end:
rjmp end ;End of program
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