Microchip Technology dsPIC33F Family Manual de usuario descargar pdf (Pagina 4)

dsPIC33F Family Reference Manual

12.3 CAPTURE EVENT GENERATION

12.3.1 Timer Selection

Each dsPIC33F family device has one or more input capture channels. Each channel can select

between Timer2 and Timer3 for its time base. Selection of the timer resource is accomplished

through the Input Capture Timer Select (ICTMR) bit in the Input Capture Control (ICxCON<7>)

OSC/2), or an external clock

source applied at the TxCK pin.

12.3.2 Input Capture Event Modes

The Input Capture module captures the 16-bit value of the selected timer (Timer2 or Timer3),

when a capture event occurs. A capture event is defined as a write of a timer value into the

capture buffer.

The Input Capture modes are configured by setting the appropriate Input Capture Mode

(ICM<2:0>) bits in the Input Capture Control (ICxCON<2:0>) register. Table 12-1 lists the Input

Capture mode and capture events for the different bit settings. The user-assigned application

must disable the Input Capture module (i.e., ICM<2:0> = 000) before changing a Capture mode.

Figure 12-2 illustrates the capture events for various Capture modes.

Table 12-1: Input Capture Modes

ICM<2:0>

Value

Input Capture Mode Capture Event Generation

000 Module disabled —

001 Edge Capture mode On both rising and falling edge of the capture input signal

010 Falling Edge mode On the falling edge of the capture input signal

011 Rising Edge mode On the rising edge of the capture input signal

100 Prescaler mode (divided by 4) On every 4th rising edge of the capture input signal

101 Prescaler mode (divided by 16) On every 16th rising edge of the capture input signal

110 Unused (module disabled) —

111 Sleep/Idle Wake-up mode No capture event

1 2 3 4 5 6 7 8 9 ... 15 16

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Microchip Technology dsPIC33F Family Manual de usuario Pagina 4