SPI MOSI dummy data and the clock questions

Question

Hello everyone, 
 I'm working on the project which uses RA6M5 MCU. 
 I'm investiaging some SPI issues. I have a couple of questions: 1. When the host reads the data from the slave over SPI MISO, the MOSI sends the dummy data 0x00. Is there a way to send some data other than the 0x00(such as 0x3F)? Please see the MOSI data in Red box. The Saleae Logic 8 is used to capture the SPI data: 
 
 2. The clock provided by the SPI driver doesn't seem consistent. Please see the screen shot below for the SPI captures. The Red box 1 is 80ns. The Red box 2 is 40ns. I'm wondering why the clock isn't always the same. I'm not sure if this clock inconsistency could cause some issues when the host communicates with the slave chip. 
 
 Thanks!

PS_Renesas · Answer

Hi pilot! 
 
 Thank you for reaching out to Renesas! In response to your first query, you can use the below function of the FSP as it points to both transmit buffer and receive buffer:

fsp_err_t R_SPI_WriteRead 
 ( 
 spi_ctrl_t *const 
 p_api_ctrl ,

void const * 
 p_src ,

void * 
 p_dest ,

uint32_t const 
 length ,

spi_bit_width_t const 
 bit_width

)

Also, you can refer to the below link for the further explanation of the above function: RA Flexible Software Package Documentation: SPI Interface (renesas.github.io) 
 And, in response to your second query, it would be great if you could share your project, so I can figure out what can be the issue. 
 
 Best Regards, 
 Payodhi