fix SPI CLOCK DIV with F_CPU @ 64MHz

Author: hathach

libraries/SPI/SPI.cpp

@@ -188,17 +188,18 @@ void SPIClass::setClockDivider(uint8_t div)
 {
   uint32_t clockFreq;
 
-  if (div >= SPI_CLOCK_DIV128) {
+  // Adafruit Note: nrf52 run at 64MHz
+  if (div >= SPI_CLOCK_DIV512) {
     clockFreq = SPI_FREQUENCY_FREQUENCY_K125;
-  } else if (div >= SPI_CLOCK_DIV64) {
+  } else if (div >= SPI_CLOCK_DIV256) {
     clockFreq = SPI_FREQUENCY_FREQUENCY_K250;
-  } else if (div >= SPI_CLOCK_DIV32) {
+  } else if (div >= SPI_CLOCK_DIV128) {
     clockFreq = SPI_FREQUENCY_FREQUENCY_K500;
-  } else if (div >= SPI_CLOCK_DIV16) {
+  } else if (div >= SPI_CLOCK_DIV64) {
     clockFreq = SPI_FREQUENCY_FREQUENCY_M1;
-  } else if (div >= SPI_CLOCK_DIV8) {
+  } else if (div >= SPI_CLOCK_DIV32) {
     clockFreq = SPI_FREQUENCY_FREQUENCY_M2;
-  } else if (div >= SPI_CLOCK_DIV4) {
+  } else if (div >= SPI_CLOCK_DIV16) {
     clockFreq = SPI_FREQUENCY_FREQUENCY_M4;
   } else {
     clockFreq = SPI_FREQUENCY_FREQUENCY_M8;

libraries/SPI/SPI.h

@@ -137,16 +137,18 @@ void SPIClass::transfer(void *buf, size_t count)
 extern SPIClass SPI;
 #endif
 
-// For compatibility with sketches designed for AVR @ 16 MHz
+// For compatibility with sketches designed for AVR @ 64 MHz
 // New programs should use SPI.beginTransaction to set the SPI clock
-#if F_CPU == 16000000
+#if F_CPU == 64000000 // feather52 run @ 64Mhz
   #define SPI_CLOCK_DIV2   2
   #define SPI_CLOCK_DIV4   4
   #define SPI_CLOCK_DIV8   8
   #define SPI_CLOCK_DIV16  16
   #define SPI_CLOCK_DIV32  32
   #define SPI_CLOCK_DIV64  64
   #define SPI_CLOCK_DIV128 128
+  #define SPI_CLOCK_DIV256 256
+  #define SPI_CLOCK_DIV512 512
 #endif
 
-#endif
+#endif