DS90UB962-Q1: Auto-ACK Timing Considerations with Remote Writes

David Shumate

Part Number: DS90UB962-Q1

Hi Team,

My customer is investigating using Auto_ACK_All for startup of their camera. If we decided to enable auto-ack for our “Global” imager initialization, instead of waiting for Port 0 ACK/NACK, is there anything we need to consider in our implementation?

- For example, do we need to make sure there is certain spacing between I2C messages when doing remote writes to avoid I2C bus errors?

- Any other factors to consider here?

We would disable auto-ack for all the messages after the we have all the imagers initialized.

Thanks,

David

8 months ago

0 Zoe Bison 8 months ago

TI__Genius 11785 points

Hi David,

Auto ACK will allow the transaction from the serializer to be acknowledge without receiving an ACK/NACK, preventing the bus from waiting for the ACK/NACK and proceeding to the next transaction. However, the device will not be able to receive NACKs in this configuration.

Best,

Zoe

0 David Shumate 8 months ago in reply to Zoe Bison

TI__Expert 6055 points

Thanks for the response Zoe, Is there risk if the two I2C busses are running at different speeds? Just as a dummy example let's say that the deseralizer bus is running at 1Mhz and the seralizer is running at 400khz. In this situation the seralizer would not be as fast as the deseralizer so would need to hold pending commands in a que, is this okay or are there special considerations that need to be taken?

0 Zoe Bison 8 months ago in reply to David Shumate

TI__Genius 11785 points

Hi David,

If the I2C bus is operating at different speeds, there will be a change in the I2C throughput of the SerDes that would need to be considered. The throughput calculation for different configurations. This is discussed in the following FAQ: [FAQ] DS90UB953-Q1: How do I determine I2C throughput for ADAS remote devices?

Peripherals on a common I2C bus would have the same frequency.

Best,

Zoe

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DS90UB962-Q1: Auto-ACK Timing Considerations with Remote Writes