Bug with the IIC

J

Jeff1111

New Member

• Apr 1, 2010

• #1

Hello,
I have programmed a uC MC9S08QG8. I try to communicate with a EEPROM 24LC04B/P, but I can write and Read only when I'm on step by step (sure). When i let the program going to his own speed, something don't work. I have look after the speed of transmission, but nothing hapened. No errata, what else?
And It works in step by step!!!
Any idea?

 

E

Electronworks

New Member

• Apr 1, 2010

• #2

I2C should only run at 400kHz. is your micro generating the I2C bus too fast? Also have you allowed 10ms for the EEPROM to program? Most people (including me) forget this step and when you go to read back the EE memory it comes out as FFs

 

J

Jeff1111

New Member

• Apr 1, 2010

• #3

Electronworks said:

I2C should only run at 400kHz. is your micro generating the I2C bus too fast? Also have you allowed 10ms for the EEPROM to program? Most people (including me) forget this step and when you go to read back the EE memory it comes out as FFs

Click to expand...

No, it's not! I have try with many different speed.

What do you mean by that? when I start the uC? Or between a write and a read?

 

E

Electronworks

New Member

• Apr 1, 2010

• #4

The datasheet should tell you the minimum write time for the E2. Normally you give it your address then your data, then you have to wait at least 6ms for the internals of the E2 to actually program the memory location, so you need to implement a delay after each write cycle

 

J

Jeff1111

New Member

• Apr 1, 2010

• #5

You mean this time: Bus free time: Time the bus must be free before a new transmission can start "Min 1300ns" -> 1.3us???

 

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Electronworks

New Member

• Apr 1, 2010

• #6

it is the 'internal write cycle time' - look in the electrical characteristics in the datasheet

 

J

Jeff1111

New Member

• Apr 2, 2010

• #7

It works! I put a delay of 100us after each transmission and it was ok! Thank you for all! have a good day!

 

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Electronworks

New Member

• Apr 2, 2010

• #8

Hmmm. Obviously something is working, but I think 100us is too short. You need 6ms (ideally 10ms) for the E2 to write to memory.

 

J

Jeff1111

New Member

• Apr 2, 2010

• #9

But in the datasheet, nothing take more than 5us. one think is in [ms] and it is "Max time write".