Accessing Peripherals on I2C bus

azhagiri s

Hi,

we are trying set of tests simultaneously ,accessing the example code given in spectrum digital website. following tests we performed 1.LED TESTS 2.VIDEO LOOP BACK TEST 3. DDR MEMORY TESTS.. These 3 tests are given as individual examples in sample code.. we combined these codes and executed in infinite loop.. Say LED tests in infinite loop means it should run continuously, but LED blinking is stopping after some count.. 10, 12, 20,, video decoder and io expander slaves are connected via single I2C bus. can we operate these peripherals simultaneously in infinite loop.. is it creating problem to stop LED ? suggest us solution ..

Regards,

azhagiri.s

over 8 years ago

0 Arvind Singh over 8 years ago

Mastermind 6115 points

Hi Azhagiri,

You can not operate on these peripherals simultaneously in infinite loop using I2C , and yes it might be the problem to stop LED.
As I2C is a multi-master and multi-slave bus, Two or more masters can access it but not at same time . They will follow Arbitration rule and who soever wins will own I2C bus. Mean while Other one will wait till I2C gets free.

Check-out some tips for I2C peripherals.
processors.wiki.ti.com/.../I2C_Tips

0 azhagiri s over 8 years ago in reply to Arvind Singh

Intellectual 655 points

Hi arvind thank you..

I ll look in I2C tips. Is there any other option to run these applications simultaneously..

Regards,
azhagiri.s

0 Titusrathinaraj Stalin over 8 years ago

TI__Guru** 116100 points

Hi,
Can you comment it out the any one of the I2C related stuff (video decoder or IO exapnder) and see its causing the LED to stop ?
Why do you want to run those test cases simultaneously and not one by one ?
Is there any specific reason, if yes, we would like to suggest some better idea.

0 azhagiri s over 8 years ago in reply to Titusrathinaraj Stalin

Intellectual 655 points

Hi,
we comment video decoder and run only LED tests it is running perfectly in infinite loop. when combining it is stopping. There is no specific reason to run those test cases in infinite loop just we tried.

Regards ,
azhagiri

0 Arvind Singh over 8 years ago in reply to azhagiri s

Mastermind 6115 points

Hi Azhagiri,

Thanks for the update.
It's expected behavior only, I2C bus cannot be accessed by two devices at at same time.

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Accessing Peripherals on I2C bus