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adar7251 connect with stm32 have some question

Question asked by walle on Jun 22, 2018
Latest reply on Jun 26, 2018 by walle

Hi   I have some question with STM32 connect with ADAR7251.

SPI MODE select mode3    (SPI_CPOL = SPI_CPOL_High;     SPI_CPHA = SPI_CPHA_2Edge;)   SPICLK is 380KHz,

SPI CS is also set 0,  ADAR7251 reset pin set 1. FAULT pin have a 10K pull-up Res. but other ADC pin connect with STM32,I  havn't INIT.  AIN pin is not connect to a device except RC.

CM pin is 1.5V, REGOUT pin is 1.8V. but PLLFILT pin is 0V. xin and xout have 19.2MHz. addr15 is set 0.

 

For this state, I use STM32 SPI config adar7251,but the PLL Status register  is return 0(or havn't return), Fault pin is also 0V, but sometimes ,fault pin change to 1,and MISO have   irregular data.Yellow is SPICLK,  Green is MISO pin. STM32 send 14byte,will return 2 different byte one time. I don't understand this .

 

And What situation causes Fault  pin pull down?. Havn't initialize register ? Or a hard error. DataSheet cann't find a detailed description .

Could you have me? Thank you.

 

 

R44  R38 is  NC

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