EC Mode

The External Clock (EC) mode allows an externally generated logic level signal to be the system clock source. When operating in EC mode, an external clock source is connected to the OSC1/CLKIN input pin. The OSC2/CLKOUT pin is available as a general purpose I/O pin or as the CLKOUT signal pin.

EC mode provides three Power mode selections:

The Oscillator Start-up Timer (OST) is disabled when EC mode is selected; therefore, there is no delay in operation after a Power-on Reset (POR) or wake-up from Sleep. Because the PIC® MCU design is fully static, stopping the external clock input will have the effect of halting the device while leaving all data intact. Upon restarting the external clock, the device will resume operation as if no time had elapsed.

The figure below shows the pin connections for EC mode.

Figure 1. External Clock (EC) Mode Operation
Note:
  1. 1.Output depends on the setting of the CLKOUTEN Configuration bit.