I2C MDB out of phase

[vinicius_olivei]

Hello NXP community,

I'm having some troubles with I2C MDB Tooldbox implementation using S32144k.

Basicaly I´m sending Write command with address 0xC8 to receive 0x08 address information from this I2C device.

I have this same implementation in S3K144K and another microcontroller.

From NXP the starting of the CLOCK is in PHASE with start of the message sent (address + data), and the I2C device do not reply to my request.

From the other microcontroller with the same implementation and same clock speed, the start of the message sent (address + data) is with 1 clock delay, and I get the information from the I2C device that I was expecting.

I have attached some pictures.

Is there any sort of way to modify/delay the message sent? For example modify low level drivers.

Thank you!

[constantinrazva]

Hello vinicius.oliveira@enfas.de‌,

In both cases we have the same I2C frame:

- the START condition is defined in I2C protocol as a high-to-low transition on the SDA line, while SCL is high

- the data is then sampled on the rising edge of SCL

Having this in mind, in both cases we have a START condition at first (while SCL is high, SDA goes from high to low), then we get the following data (sampled on the rising edge of SCL): b 1100 1000 (0xC8). 

In the NXP_log picture you have highlighted the SCL transitioning from high to low, while in the OTHER_uc_log you have highlighted SDA transitioning from low to high. Note that you have SDA and SCL reversed in the two images.

To answer to your direct question, there is no way to delay the I2C - and there is no phase and/or polarity as in the SPI case - they start with the START condition mentioned above. But again, even though I'm not sure what the problem might be, the 2 frames carry the same information (Write 0xC8 frames from the 2 images you posted).

If you can share what type of device you're trying to communicate with, I can take a look at it, maybe try it out if I can get my hands on the hardware necessary. 

Kind regards,

Razvan.