Bcm5396 SPI Comprehension

 

Reference link: https://pan.baidu.com/s/1kuXJmULwtjOW1TeOuTRPQQ

* Clock polarity and phase

Bcm538x/bcm5396 is used to send/receive SPI data according to the following standards:
? Clock polarity (cpol) = 0 or 1;
? Clock Phase (cpha) = 1;
Cpol is determined by the sck value that the SS changes from high to low when it is idle.

These parameters are not programmable on bcm538x/bcm5396. The external SPI device must be consistent with the bcm538x/bcm5396 parameters for normal communication.
Clock Polarity(Cpol)-if this parameter is 1Internal shift clock of the master deviceReverse. If this parameter is set to 0, the sck is idle. If cpol = 1, The sck is idle.
Clock Phase(Cpha)-if this parameter is set to 1, the sck is shifted to 180 ° relative to the internal shift clock of the host.Suppose cpol = 0If this parameter is set to 0, the data is locked on the rising edge of sck. If this parameter is set to 1, the data is locked along the sck descent edge.If cpol = 1Is opposite to cpol = 0.
For information about cpol and cpha, see Motorola? SPI interface specification.

 

 

 

 

 

* Bcm5396 sampling edge

When the SS is from 0 to 1, sclk = 1, so cpol = 1; at the same time, the cpha of BCM is fixed to 1; therefore, it is the rising edge of sclk for sampling;

 

 

* Bcm5396 operation sequence:

 

 

 

 

Bcm5396 SPI Comprehension