Regarding TSN PTP Function Configuration

[hankwang]

Hi,

I have a question regarding PTP implementation. We need to read IMU data paired with a gPTP timestamp.

Our hardware pin configuration is as follows:

• CCM_CLKO1 (AH20)  <- 1588_TRIG

• CCM_CLKO3 (AK20)  <- IMU Sensor Interrupt

• CCM_CLKO4 (AJ21)  (IMU PPS) ->  CCM_CLKO1 (1588_TRIG)

Based on this, our understanding of the Pin Mux configuration is:

• CCM_CLKO4 needs to be configured as ALT1 (1588_PP2)

• CCM_CLKO3 needs to be configured as ALT1 (1588_TRIG2)

• CCM_CLKO1 needs to be configured as ALT1 (1588_TRIG1)

When an IMU interrupt occurs, the hardware signal triggers the 1588 timestamp mechanism on the i.MX95, allowing the SoC to capture the PTP hardware timestamp at the exact moment of the event.

Upon receiving the IMU interrupt, the application reads the IMU data and retrieves the corresponding PTP timestamp, then combines both into a single data package. Please confirm if our understanding is correct.

Additionally, please help us verify the following two points:

1. Can the i.MX95 capture the PTP hardware timestamp at the exact time of the IMU interrupt via the aforementioned 1588_TRIG / 1588_PP hardware signals?

2. Does the Linux / NXP driver provide a corresponding API or /dev/ptpX interface for the application to retrieve this hardware-latched timestamp?

Thank you for your support, and I look forward to your reply

[pengyong_zhang]

Hi @hankwang 

Q1. No problem.

Q2. By connecting the IMU's INT/DRDY input using 1588_TRIG1/TRIG2 (external trigger input), the NETC Timer will hardware-latch a nanosecond-level PTP timestamp at the exact moment of the interrupt edge (stored in the ETTS FIFO and generating an interrupt). The application can then read this timestamp through the standard EXTTS interface on /dev/ptp0.

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