How can I change (lower) the SPI bitrate?

[RudolfAtHome]

My Analyser shows me a frequency of 16 MHz. In SPI.h I don't see a way to change this. Who can show me the right way?

[Andy2No]

I haven't tried it with this core yet, but in standard Arduino, it works like this:

// include the SPI library:
#include <SPI.h>

// set pin 10 as the slave select for the device
const int slaveSelectPin = 10;  // There isn't one called that - it's CS, active low.  Can be any unused GPIO pin.

void setup() {
  // set the slaveSelectPin as an output:
  pinMode (slaveSelectPin, OUTPUT);
  digitalWrite(slaveSelectPin,HIGH);

  // initialize SPI:
  SPI.begin();

  //SPI.beginTransaction(SPISettings(10000000, MSBFIRST, SPI_MODE3)); // Pick a speed and mode, to suit the device

  SPI.beginTransaction(SPISettings(100000, MSBFIRST, SPI_MODE0)); // slow down
}

[RudolfAtHome]

I ask for water and you mention that there is some in the Atlantic Ocean. That doesn't help.