I want to make an optimized spi clock.

[odenwar]

The SDK version is using version 17 and I am using NRF52832.

I checked the following scope waveform for the next SPI communication.

   

Question

1. I want to remove the following area (delay).
             
   
   
2. Is it possible to change the voltage of that IO to 1.8 volts using the source code?

[Kenneth]

For the nRF52832 the SPI hardware peripheral handle the MISO, MOSI and CLK pin. So before and after every SPI transaction the application or driver will need to handle the CS pin, for instance from the interrupt handler after the SPI transmission have finished, so there will be some delays.

If you use the nRF52840 you can find that the 4th SPI instance (SPIM3) have hardware support also for CS pin:
https://infocenter.nordicsemi.com/topic/ps_nrf52840/spim.html#topic