asm330lhhxg1 "who_am_i" register is reading back 0x48. Should be 0x6.

[arifkhan]

Connected STEVAL_$MKI243AA board to a nucleo-g491re board using 4 wire spi interface. The spi bus is setup to run @ 146 Kbits/sec. Reading back bad data. 

WHO_AM_I is 0x48

PIN_CTRL is 0x3E

 

Not sure but seem like the device is power

[TDK]

Why should it be 0x6?

 

[Federica Bossi]

Hi @arifkhan ,

The correct whoami, as reported also by @TDK , is 6Bh.

Probe with a logic analyzer and check:

• MOSI address byte
• MISO timing
• whether the returned byte is shifted by 1 bit
• whether CS stays stable

Did you try the reading also in I2C or SPI3?

[arifkhan]

hello Federica,

 

Yes, i have the scope connected to the 4 spi signals, I see 0x8F go out on the MOSI and I see 0x48 on the MISO wire every time.  I put a 10k pullup on the CS wire and also a 10K pulldown on the INT1 signal.

 

Yes I tried the I2C bus and I am able to read 0x6B data back from the WHOAMI register.

 

Rgds

[arifkhan]

hello Federica,

 

Is there some setup to this part at power up ?

 

I am completely at loss right now I would really appreciate some help from ST micro.

 

Rgds

 

[arifkhan]

I am really disappointed with the help i have received from ST micro. 

I should start looking for an alternate solution and and also transition away from using all STmicro parts in the future given there level of support.

[Andrew Neil]

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@arifkhan wrote:

I am really disappointed with the help i have received from ST micro. 

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You still haven't provided your schematic, or any code

How to write your question to maximize your chances to find a solution

 

Something is clearly very wrong with your MISO:

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@arifkhan wrote:

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Do you have a good ground connection?

[arifkhan]

Hello Andrew,

 

Why do you say that MISO is bad? At the start of the SPI cycle, the IMU will not drive this signal, and so the MISO line would be floating (which is what is being observed). in the second part of the SPI cycle, read data is clearly being driven back by the IMU i.e. 0x48 (which is the problem. It should be 0x6B). 

 

Thx.

 

Rgds.