LPC55S36 I3C SCL isn't completed during Hot Join

[sam_wu_7911]

Hi there,

I'm trying to implement the flow of hotjoin with the I3C bus. However, when the target triggers the hot join address (0x02), the SCL stop at the 8th clock tick. No clock for R/W and ACK, do you have any idea?

螢幕擷取畫面 2025-08-19 100931.png

[Harry_Zhang]

Hi @sam_wu_7911 

May i ask is your target also lpc55s36 board?

BR

Harry

[sam_wu_7911]

Hi @Harry_Zhang

Yes, I did try the target of the LPC55S36 board.

Also, I tried another sensor IC with the same situation.

Could you please provide me with a solution for triggering the last two clock ticks? I'll appreciate it.

[Harry_Zhang]

Hi @sam_wu_7911 

When you enter Hot join,

You can try to send response ACK.

I3C_MasterEmitIBIResponse(EXAMPLE_MASTER, kI3C_IbiRespAck);

And then  dynamically assigning addresses.

BR

Harry

[sam_wu_7911]

Hi @Harry_Zhang 

Do you mean when the Controller received the Hot Join Interrupt, sending a response ACK?

Is it like the code below?

螢幕擷取畫面 2025-08-25 162747.png

BRs,

Sam 

[Harry_Zhang]

Hi @sam_wu_7911 

Yes, you are right. and then dynamically assigning addresses.  you can try.

BR

Harry

[sam_wu_7911]

Hi @Harry_Zhang 

After applying your solution, the last two clocks appear. However, after the ack is the stop condition, and that doesn't match the I3C spec.

22. Hot Join ACK with stop condition.png

Following the spec, there shall be a repeated START condition rather than a STOP. Do you have further ideas?

15. HJ (Hot-join).png

[Harry_Zhang]

Hi @sam_wu_7911 

In i3c spec, after the ack is the stop condition or repeated start condition.

Harry_Zhang_0-1761878366328.png

This is my code. 

Harry_Zhang_1-1761878525136.pngHarry_Zhang_2-1761878543145.png

Harry_Zhang_3-1761878585315.png

You can try.

BR

Harry