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ADXL355, SPI - cannot write registers

Question asked by georgedl on Aug 7, 2018
Latest reply on Aug 8, 2018 by NevadaMark

I have a ADXL355 EVAL wired up to the SPI B bus on my MPC565 processor board. Registers reads work fine but writes don't stick. I have verified against the datasheet with a scope (A7-A0 and R/~W in the first 8 bits). I have tried SCLK active low and data driven on leading edge as well as SCLK active high with data driven on trailing edge. Clock is 2MHz.

 

Write 0x52 to 0x2F to reset ( I cannot actually know if this has any affect)

Write to 0x04 to 0x2D to take chip out of standby and disable DRDY.

Read 0x2D to verify previous setting - never changes from default 0x01, neither with immediate read-back nor after waiting several seconds to read-back.

 

I believe reads are working because 0x29 returns 0x60 and 0x2C returns 0x81. Chip ID registers (0-3) also return expected values.

 

The EVAL board has a jumper on a header named STBY but pin 2 on that header is connected to a RESERVED pin (7) on the ADXL355. The part behaves the same way for either jumper position.

 

I must be doing something silly but I haven't found it. Any guesses?

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