LMP90100: SPI Data Read issue, LSB not reading correctly.

Hi parth kanani,

Parth Kanani said:

I am following correct sequence but I am always missing LSB. For this example I should be reading back 0x13 but I always read 0x12. Same for all resistors, LSB always read as '0'.

It's a little unclear what you mean here. What is it exactly you are trying to accomplish? 

Are you trying to read back register address 0x13 and are instead reading back data from register 0x12? Did you write 0x13 to a register but read back 0x12? Are you trying to read data and are not reading back your expected result?

What sequence are you referring to?

Please be as specific as possible.

Best Regards,

Angel

I am experiencing an issue with SPI communication while reading specific registers. For example:

• When I read register 0x22, the expected value is 0x13, but I am receiving 0x12.
• Similarly, reading register 0x2C should return 0x25, but I am getting 0x24.

Upon closer inspection of the SPI signals (refer to the attached image), it appears that the last bit of MISO data (LMP90100) is transitioning prematurely—almost halfway through the clock cycle. This behavior seems to be causing the last bit to be missed during data capture. First 7 bits are fine. I tried all SPI modes with no luck. 

Hi Parth,

I'll take a look at this and get back to you by Friday.

Best Regards,

Angel