LSM6DS3 SPI Bug?

[Wakkk]

Hello, I use an AT32F403A MCU to connect LSM6DS3 IMU via SPI 4-wire, then I read the WHO_AM_I register at 0x0F. According to the datasheet, the return value should be 0x69, but the chip returned 0x44. Then I repowered the board, and the value seemed to change to 0x7F. Then I read the Acc and Gyro data. From the logic analyzer, there seem to be some abnormal glitches, which looks like some connection problems, but I checked the wiring and I can't find the problem. Can somebody help me figure out the problem? Thank you.

[Federica Bossi · Accepted solution]

Hi @Wakkk ,

Yes, the symptoms you describe strongly suggest communication issues between your AT32F403A MCU and the LSM6DS3 sensor.

MOSI, MISO, SCLK, CS lines correctly connected? Did you follow the datasheet?

Start with a low SPI clock (e.g., 1 MHz) to ensure signal integrity, then increase if stable. Ensure CS is properly driven low before and high after each SPI transaction.

[Andrew Neil]

In addition to what @Federica Bossi already said,

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@Wakkk wrote:

 From the logic analyzer, there seem to be some abnormal glitches,

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Have you used an oscilloscope to see what's happening in the analogue domain?

eg, noise, ringing, unstable levels, sloppy edges, etc ...

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@Wakkk wrote:

which looks like some connection problems,

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Might also be bad decoupling?

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@Wakkk wrote:

 I checked the wiring and I can't find the problem. Can somebody help me figure out the problem?

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We can't see you hardware, so we can't check it, or comment on it.

You need to show the schematics & layout.

Also some good, clear photographs.

See: How to write your question to maximize your chances to find a solution.