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Issues with ADXL362 SPI comms

Question asked by matkey on Jul 9, 2013
Latest reply on Jul 9, 2013 by neilzhao

Hi,

 

Ive got one of Sparkfun's ADXL362 accelerometer breakout boards and have got it connected upto a Bus Pirate and can talk happily to it.

When I connect the 362 breakout board upto my Energy Micro development board, then I have issues.

I have got test code to read out address 0x00 (ADXL362_REG_DEVID_AD) 20 times in a row to verify good communications with the chip, and I read back the following

 

FF

AD

FF

AD

FF

AD

FF

AD

FF

AD

FF

AD

FF

AD

FF

AD

FF

AD

FF

AD

 

The only differences I can see between my Bus Pirate and my Enegry Micro code is that the Bus Pirate has big delays (>1mS) between CS going high/low and between bytes being sent. Both devices have 1 MHz SPI clocks.

Im looking at the wavefroms (Saleae Logic analyser) and the built in protocol decoders are matching what the Energy Micro code is reading back. And I cant see any differences between the Bus Pirate captures and the Energy Micro captures (apart from more compact transactions on Energy Micro)

The chip is powered via a GPIO pin as suggested in the datashset. I give the chip 1mS after enabling the power before I send in the first Read Register command.

 

Any ideas why I can only talk to the chip on every other command?

I have attached a screen shot of the waveforms.

 

Thanks in advance,

 

Mat

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