Reduce the SCK frequency from 16 MHz to 50 KHz for communication over SPI

Hello friends,

I am trying to control the display of a refrigerator using Arduino Mega 2560 as master over SPI protocol. I realized that the slave (display) expects the data to be sent at frequency of 50 KHz which is why the received bytes were not same as the sent bytes at 16 MHz when I analyzed lines using Logic Analyzer.

So, before posting here I tried to google the solution but did not find very solid results. I will discuss one potential solution below but I need your comments if this makes sense over SPI.

If I generate a simple square wave of 50Khz on one of the pins of arduino and connect this pin to predefined SCK pins of master arduino and slave (display), would this actually provide both master and slave with that frequency?

Moreover, you can suggest me alternative better solutions.

Thanks in advance.

Please, post a link of the display unit of your refrigerator to check for ourselves the what kind of SPI device it is.