Add new content to spi-frequency.md

docs/reference/pins/spi-frequency.md

@@ -1,18 +1,31 @@
-# SPI Write
+# SPI Frequency
 
-Write to the SPI Slave and return the response.
+Set the SPI clock frequency.
 
 ```sig
-pins.spiWrite(0);
+pins.spiFrequency(1000000);
 ```
 
 ## Parameters
 
-* ``value``: value	Data to be sent to the SPI slave
+* **frequency**: a [number](/types/number) to set as the frequency for SPI bus clock. This value is the number of clock changes per second (Hz).
 
-## Returns
+## Example
 
-* a [number](/types/number) Response from the SPI slave
+Read the value of the _WHOAMI_ register from the device connected to the SPI bus. The chip select line is connected to pin **0** and the SPI signals use pins **13**, **14**, and **15**.
+
+```blocks
+pins.digitalWritePin(DigitalPin.P0, 1);
+pins.spiPins(DigitalPin.P15, DigitalPin.P14, DigitalPin.P13);
+pins.spiFormat(8, 3);
+pins.spiFrequency(1000000);
+pins.digitalWritePin(DigitalPin.P0, 0);
+let command = pins.spiWrite(143);
+let whoami = pins.spiWrite(0);
+pins.digitalWritePin(DigitalPin.P0, 1);
+basic.showNumber(whoami);
+serial.writeLine("WHOAMI register value: " + whoami)
+```
 
 ## See also