Long delay between consecutive SPI writes - SAMV71 Xplained

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Hello,

 

I'm testing SPI writes on the SAMV71 and I notice there are always long delays between consecutive writes (~1.8uS)

The SPI clock is running at 9MHz, the MCU is at 300Mhz and the peripheral clock is at 150Mhz

 

The SPI writes work as expected but there always seems to be a 1.8uS delay between each consecutive write - see trace

 

For this test I am just doing an SPI byte write and then waiting for the receive data full RDRF bit to get set:

 

p_spi->SPI_TDR = DAT1;
while (!(p_spi->SPI_SR & SPI_SR_RDRF));
ans1=p_spi->SPI_RDR;

p_spi->SPI_TDR = DAT2;  
while (!(p_spi->SPI_SR & SPI_SR_RDRF));
ans2=p_spi->SPI_RDR;

 

 

Any ideas why such a long delay would occur between the writes?

 

thanks!
 

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