DS90UB927Q-Q1: Issue about I2C mapping in 927/928

Betty Guo

Part Number: DS90UB927Q-Q1

Hi team,

customer have issues about 927/928 I2C mapping. they found that in 927 side, the SCL will be pulled to low sometimes, below is customer reg setting and I2C waveform:

1. reg setting

2. 927 I2C waveform, yellow is SCL, Pink is SDA

3. 928 I2C waveform

issue: 927 SCL will be pull down and difference with 928.

Could you help to check it? thanks.

over 4 years ago

0 Michael.Walker over 4 years ago

TI__Mastermind 19720 points

Hi Betty,

What you are seeing is I2C clock stretching.

From the datasheet: "The I 2C Master located at the DS90UB927Q-Q1 serializer must support I 2C clock stretching. For more information on I 2C interface requirements and throughput considerations, refer to TI Application Note SNLA131."

Regards,

Michael W.

0 user6299967 over 4 years ago in reply to Michael.Walker

Prodigy 70 points

HI,we have debugged several days and ensure that I2C is normal,and touch panel can response.But now the interrupt pin is connected by direct wire,not through 927/928.If we want to use 928 INTB_IN and 927 INTB to transfer Touch panel interrupt trigger to SOC,How should wen configure register?Thank you!

0 Steven(Shenzhen) Shi over 4 years ago in reply to user6299967

TI__Mastermind 30515 points

yes, you need.

pls refer to d/s on the INTB application description as attached.

regards,

Steven

0 Steven(Shenzhen) Shi over 4 years ago in reply to Steven(Shenzhen) Shi

TI__Mastermind 30515 points

page 26 in the d/s

Interface

Interface forum

DS90UB927Q-Q1: Issue about I2C mapping in 927/928