FS26 Not Entering Standby & Initialization Fails – FS_STATE

[GaneshBhagwat]

Hello NXP Support,

I’m working with the following example from your knowledge base:
RTD Example: FS26 WKUP with PGOOD and EXTWAKE using a S32K3X8EVB

My goal is to put both the FS26 and the S32K3X8 controller into standby mode. While the controller successfully transitions to standby, the FS26 remains in the same state and does not follow.

Additionally, the function call:

eReturnValue |= Sbc_fs26_InitDevice();

returns not_ok, and the initialization process fails. Upon debugging, I found that Sbc_fs26_GetDeviceState() is returning 0x14 as the FS_STATE value.

According to the FS26 datasheet, I couldn't find any documentation clearly explaining the meaning of this value, particularly bit 4 (i.e., 0x14 = 0b10100). Could you please clarify what bit 4 represents in the FS_STATE register? It's not mentioned in the register description section of the datasheet.

I also came across this related post that seems to touch on a similar issue, but there is no clear resolution provided:
FS26 FS_STATES & SPI Communication

Could you please assist with the following:

1. Why is the FS26 not transitioning to standby mode alongside the S32K3X8?

2. What does the FS_STATE value 0x14 indicate, specifically the significance of bit 4?

3. What are the possible reasons for Sbc_fs26_InitDevice() returning not_ok?

Any guidance or clarification would be greatly appreciated, especially regarding the undocumented FS_STATE bits.

[guoweisun]

HI 

1. Why is the FS26 not transitioning to standby mode alongside the S32K3X8?[gw]before enter into standby mode,what's the mode of FS26? how did you operate it enter into standby mode?

2. What does the FS_STATE value 0x14 indicate, specifically the significance of bit 4?
   [gw]If no match the table value in your post picture, there is meaningless for this result.

3. What are the possible reasons for Sbc_fs26_InitDevice() returning not_ok?[gw]I should know answer in my quesitons1 reply.

[GaneshBhagwat]

1. Before entering standby mode, what state is the FS26 in? How are you attempting to transition it into standby mode?

I’m using the S32K358 development board, which includes the FS26 with the default configuration. I’m currently testing the example code provided by NXP[mentioned link in the post]. However, the Sbc_fs26_InitDevice() function is returning NO_OK, indicating the initialization is failing. As a result, the FS26 is not transitioning to the FS_INIT or any other operational state. When I read the FS_STATE register, I’m getting 0x14.

2. What does the FS_STATE value 0x14 indicate, particularly the significance of bit 4?
If this value doesn’t match any entry in the table shown in your screenshot, does it still have any defined meaning?

Also, why does the register use 4 bits when all documented FS states seem to be covered within 3 bits? The table mentions “Actual State of the Fail-Safe State Machine,” so is bit 4 indicating a special fault condition or an undocumented state?

[guoweisun · Accepted solution]

You can try to change green circled as 'no effect on RSTB and FS0B' this in S32DS:

disabled watchdog period

No monitoring the FCCU function

[GaneshBhagwat]

Thank you for your response. I checked the suggested solution, but it was still showing the same issue. On further debugging, I found that the system was entering the INVALID_FS state and was not updating any configurations from the peripherals. I reviewed the default register values and identified the SBC_FS26_FS_GRL_FLAGS_ADDR register, which indicated an overvoltage fault. Upon checking the SBC_FS26_FS_OVUV_REG_STATUS_ADDR register, I saw that it was a VMON_EXT overvoltage condition. After adjusting the circuit connection and changing the resistance values, the issue was resolved. The system now transitions properly into the FS_Init state, and other operations are working as expected. Thanks again for your support.

[GaneshBhagwat]

@YvanR Can you please have a look.