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Section 12. Input Capture

Input Capture

12.5 INPUT CAPTURE INTERRUPTS

The input capture channel can generate an interrupt based on the selected number of capture

events, as illustrated in Figure 12-4. The number of events is set by the Input Capture Interrupt

(ICI<1:0>) bits in the Capture Control (ICxCON<6:5>) register, as provided in Table 12-2. The

user-assigned application must disable the Input Capture module (ICM<2:0> = 000) before

changing the ICI<1:0> bits.

When the capture interrupt is generated on every capture event (ICI<1:0> = 00), the FIFO

overflow condition does not inhibit the capture interrupt. If the capture interrupt is not generated

on every capture event, the FIFO overflow condition inhibits the capture interrupt. Therefore, all

the captured values must be read from the capture buffer on every capture interrupt. For

example, if the capture interrupt is generated on every second capture event (ICI = 01), the

capture buffer must be read twice. Similarly, if the capture interrupt is generated on every third

capture event (ICI = 10), the capture buffer must be read three times.

Figure 12-4: Input Capture Interrupt Generation

Note: In Edge Detection Mode (ICM = 001), the interrupt is generated on every capture

event and the Input Capture Interrupt (ICI<1:0>) bits are ignored.

Table 12-2: Input Capture Interrupt Selection

ICI<1:0> Values Input Capture Interrupt Generation

00 Interrupt on every capture event

01 Interrupt on every second capture event

10 Interrupt on every third capture event

11 Interrupt on every fourth capture event

Note: Each Input Capture channel has interrupt flag status bits (ICxIF), Interrupt Enable

bits (ICxIE) and Interrupt Priority Control bits (ICxIP<2:0>). Refer to

Section 6. “Interrupts” (DS70184) in the “dsPIC33F Family Reference Manual” for

more details on peripheral interrupts.

Capture Event

Capture Interrupt

(ICI<1:0> = 0b00)

Capture Interrupt

(ICI<1:0> = 0b01)

Capture Interrupt

(ICI<1:0> = 0b10)

Capture Interrupt

(ICI<1:0> = 0b11)

1 2 3 4 5 6 7 8 9 10 11 12 ... 15 16

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Microchip Technology dsPIC33F Family Manual de usuario Pagina 7