DRA750: I2C3 behavior & START condition spec

Koichi Saito

Part Number: DRA750

Hi Expert,

This is to confirm DRA750 I2C3 behavior (and it is related to DRA750: I2C3 behavior & How to recover from I2C issue)

Customer is using FAST mode on I2C3.

According to DRA75x DataManual Table 7-36 above, th(SDAL-SCLL) - Hold time SCL low after SDA low (for a START and a repeated START condition) needs 0.6usec or longer to enter into START condition.
[Question] In other words, if Jacinto-6 receives SDA/SCL with th(SDAL-SCLL) wihich is always less than 0.6usec, Jactinto6 I2C3 module will never recognize as START condition. Is that correct ?

External I2C slave device (called as CP), which is connected to Jacinto6 I2C3, makes both SCL and SDA pins to LOW level illegally after booting up.
Customer mentions that CP SCL and SDA output timing keeps th(SDAL-SCLL) less than 0.6usec. Thus, customer wants to confirm if Jacitno6 I2C3 has never enter into START condition or not.

Best regards,
Saito

over 3 years ago

0 Brad Griffis over 3 years ago

TI__Guru*** 125430 points

Koichi Saito said:
According to DRA75x DataManual Table 7-36 above, th(SDAL-SCLL) - Hold time SCL low after SDA low (for a START and a repeated START condition) needs 0.6usec or longer to enter into START condition.
[Question] In other words, if Jacinto-6 receives SDA/SCL with th(SDAL-SCLL) wihich is always less than 0.6usec, Jactinto6 I2C3 module will never recognize as START condition. Is that correct ?

No, that's not correct. Operation outside the spec is unspecified.

0 kcastille over 3 years ago

TI__Mastermind 46582 points

Saito-san,

No that is not correct. If the hold time is met then we can guarantee that a start condition is detected. However, if the hold time is not met then a start condition may or may not be detected.

Regards,

Kyle

0 Koichi Saito over 3 years ago in reply to kcastille

TI__Intellectual 2525 points

Hi Brad and Kyle,

Thank you for the answer but customer is still confused.

Customer understand that "Holdtime th(SDAL-SCLL) 0.6usec or more" is the condition/requirement on which START-condition can be detected by J6 I2C module.

And then customer is asking following question:
- What is the condition/requirement on which START-condition can NOT be detected by J6 I2C module ?

Best regards,
Saito

0 kcastille over 3 years ago in reply to Koichi Saito

TI__Mastermind 46582 points

Saito-san,

That is not specified or tested on the TI side.

Regards,

Kyle

0 Koichi Saito over 3 years ago in reply to kcastille

TI__Intellectual 2525 points

Hi Brad and Kyle,

Thank you for the answers. This thread is closed.

Best regards,

Saito

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DRA750: I2C3 behavior & START condition spec