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APPLICATION OVER I2C
Kıvanç ÖZBEK
504031549
What is I2C?
• 2-wired communication interface
• Communication protocol used in small
areas
• Defined in 1980’s by Philiphs
• Bidirectional data transmission
• 7 bit slave address
• Acknowledgement after each byte
I2C Properties
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Random selection procedure
Transmission capacity up to 400 KHz
Line length up to 4 meters
Line capacitance up to 400 pF
Divice capacitance up to 10 pF
Roles
• Master
– Controling the clock signal
– Defining the slave address
– Defining the Start – Stop conditions
• Slave
– Sending ack after each byte
– Controling the data line during read
operations
– Taking clock from the line
About the application
About the application
• The term open-collector typically refers to a transistor
output where the collector (output) of the transistor is not
connected to a positive voltage. Since a transistor used
in outputs is a saturated switch, the collector needs to be
connected to a positive voltage to complete the transistor
circuit. This positive voltage need not be any specific
value as long as it is above the saturation of the
transistor. Because of this, an open collector output can
be connected to a range of voltages using a pullup
resistor. This resistor is required for the output to
function as it completes the transistor's circuit.
About the application
About the application
About the application
About the application
wvalue=0x00;
rvalue = outp(data,wvalue);
delay(wait);
wvalue=0x0f;
rvalue=outp(control,wvalue);/*scl ve sda 1 yapildi*/
delay(wait);
wvalue=0x80;
rvalue = outp(data,wvalue);/*sda 0 yaparak start cond. olusturuldu*/
About the application
wvalue=0x00;
rvalue=outp(control,wvalue); /*scl 0 yapildi*/
delay(wait);
wvalue=0x80;
rvalue = outp(data,wvalue); /*sda 0 yapildi*/
delay(wait);
wvalue=0x0f;
rvalue=outp(control,wvalue); /*scl 1 yapildi*/
delay(wait);
wvalue=0x00;
rvalue = outp(data,wvalue); /*sda 1 yapilarak stop cond. olusturuldu*/
delay(wait);
About the application
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check:
for(i;i<5;i++){
rvalue=inportb(status);
rvalue<<=4;
delay(wait);
if(rvalue>127){ //scl 0 okundu
delay(wait);
rvalue=inportb(status);
rvalue<<=4;
if(rvalue<128){ //scl 1 okunursa hat mesgul
printf("Hat mesgul\n");
i=0;
}
else{//isMain 0 ise sda 1 kalacaktir dolayisiyla ana master calisir
wvalue=isMain;
rvalue = outp(data,wvalue);//sda belirlenerek hat sahipligi olustu
delay(wait);
}
About the application
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}
}
printf("Hat uygun kullanilabilir\n");
wvalue=0x00;
rvalue=outp(control,wvalue); //scl 0
delay(wait*2);
if(inportb(status) > 127){ //sda kontrol edildi
printf("Ana master calisacak\n");
goto check;
}
Encountered Difficulties
• No direct access to parallel port in XP
– Because it is not allowed to use ports directly
in windows xp, windows me is used.
• No device to watch parallel port outputs
– There were no hardware to watch the outputs
so again parallel port is used to see what is
written to the port.
• Outer power supply
– Game port pin 1(Vcc) and pin 4(Gnd) used.
Thank you for your interest
Questions?