Support Tools > CPU Speed menu for Teensy 4.0

teensy4/clockspeed.c

 
 // Define these to increase the voltage when attempting overclocking
 // The frequency step is how quickly to increase voltage per frequency
-// The datasheet says 1300 is the absolute maximum voltage.  The hardware
-// can actually create up to 1575, but going over 1300 risks damage!
+// The datasheet says 1600 is the absolute maximum voltage.  The hardware
+// can actually create up to 1575.  But 1300 is the recommended limit.
+//  (earlier versions of the datasheet said 1300 was the absolute max)
 #define OVERCLOCK_STEPSIZE  28000000
-#define OVERCLOCK_MAX_VOLT  1300
-//#define OVERCLOCK_MAX_VOLT  1575 // Danger Will Robinson!
+#define OVERCLOCK_MAX_VOLT  1575
 
 
 uint32_t set_arm_clock(uint32_t frequency);

teensy4/startup.c

 	configure_systick();
 	usb_pll_start();	
 	reset_PFD(); //TODO: is this really needed?
-	
-	set_arm_clock(600000000);
-	//set_arm_clock(984000000); Ludicrous Speed
+#ifdef F_CPU
+	set_arm_clock(F_CPU);
+#endif
 
 	asm volatile("nop\n nop\n nop\n nop": : :"memory"); // why oh why?