i2c

 i2c

heiio everyone;
i hav some queries regarding i2c communication

1.what is the range an i2c communication travel without affecting the data

2.how many devices can we connect on i2c-i have read 127 addresses, can u explain me this?

3. what is the difference between i2c,rs232 and rs484

thank u all

 RE: i2c

1. are you even aware of the purpose of i2c? signal degradation can occur because of many reasons, but the protocol was invented to couple ICs hence devices in relative proximity. i2c will function as long as the distance is less than 12 feet. note that decreasing the clocks frequency below 500 Hz can increase the range to about 100 meters, if the bus load is kept under control.

2. the original i2c implementation had an address space of 7 bits, which was later extended to 10 bits.

3. please read the specifications and compare.

 RE: i2c will function as long as the distance is less than 12 feet

No, that is not true.

With careful design, you can get over 12 feet; a poor design won't even manage 12 feet.

There is no specific distance limit; you have to look at the other parameters - capacitance, in particular...

To the OP: Note that this has nothing to do with Keil nor the 8051 - get the I2C specification and study it!

 no such thing

i2c will function as long as the distance is less than 12 feet
male cow manure!
IIC will function as long as the drive vs the line capacitance is OK. That can be exceeded anywhere between a few inches and many feet.

If you need go farther NXP has "IIC amplifiers" that can drive more capacitance.

Erik

 RE: no such thing

alright, alright, I was just giving an example for a total bus capacitance of 400 p/F...sorry, please don't bite my head off! but it is a good thing you corrected me and alerted the OP!

 which is "an example" again

I was just giving an example for a total bus capacitance of 400 p/F
the "total bus capacitance" you can handle, again depends on the pullup resistors.

no "head biting" just facts.

everything re IIC depends on.

Yes, if you use the minimum pullup resistors (can your uC handle that??) you can handle the maximum capacitance.

Erik