PIC16F753 datasheet(87/230 Pages) MICROCHIP

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DS40001709C-page 87

PIC16F753/HV753

11.5.4

RISING EVENT DEAD BAND

Rising event dead band adds a delay between the

COGxOUT1 signal deactivation and the COGxOUT0

signal activation. The rising event dead-band time

starts when the rising_event output goes true.

See

Section 11.5.1,

Asynchronous

Delay

Chain

Dead-band Delay and Section 11.5.2, Synchronous

Counter Dead-band Delay for more information on

setting the rising edge dead-band time.

11.5.5

FALLING EVENT DEAD BAND

Falling event dead band adds a delay between the

COGxOUT1 signal deactivation and the COGxOUT0

signal activation. The falling event dead-band time

starts when the falling_event output goes true.

See

Section 11.5.1,

Asynchronous

Delay

Chain

Dead-band Delay and Section 11.5.2, Synchronous

Counter Dead-band Delay for more information on

setting the rising edge dead-band time.

11.5.6

DEAD-BAND OVERLAP

There are two cases of dead-band overlap:

• Rising-to-falling

• Falling-to-rising

11.5.6.1

Rising-to-Falling Overlap

In this case, the falling event occurs while the rising

event dead-band counter is still counting. When this

happens, the COGxOUT0 drive is suppressed and the

dead band extends by the falling event dead-band

time. At the termination of the extended dead-band

time, the COGxOUT1 drive goes true.

11.5.6.2

Falling-to-Rising Overlap

In this case, the rising event occurs while the falling

event dead-band counter is still counting. When this

happens, the COGxOUT1 drive is suppressed and the

dead band extends by the rising event dead-band

time. At the termination of the extended dead-band

time, the COGxOUT0 drive goes true.

11.6

Blanking Control

Input blanking is a function, whereby the event inputs

can be masked or blanked for a short period of time.

This is to prevent electrical transients caused by the

turn-on/off of power components from generating a

false input event.

The COG contains two blanking counters: one

triggered by the rising event and the other triggered by

the falling event. The counters are cross-coupled with

the events they are blanking. The falling event

blanking counter is used to blank rising input events

and the rising event blanking counter is used to blank

falling input events. Once started, blanking extends for

the time specified by the corresponding blanking

counter.

Blanking is timed by counting COG_clock periods from

zero up to the value in the blanking count register. Use

Equation 11-1 to calculate blanking times.

11.6.1

FALLING EVENT BLANKING OF

RISING EVENT INPUTS

The falling event blanking counter inhibits rising event

inputs from triggering a rising event. The falling event

blanking time starts when the rising event output drive

goes false.

The falling event blanking time is set by the value

contained in the COGxBKF register (Register 11-12).

Blanking times are calculated using the formula shown

in Equation 11-1.

When the COGxBKF value is zero, the falling event

blanking is disabled and the blanking counter output is

true, thereby allowing the event signal to pass straight

through to the event trigger circuit.

11.6.2

RISING EVENT BLANKING OF

FALLING EVENT INPUTS

The rising event blanking counter inhibits falling event

inputs from triggering a falling event. The rising event

blanking time starts when the falling event output drive

goes false.

The rising event blanking time is set by the value

contained in the COGxBKR register (Register 11-11).

When the COGxBKR value is zero, the rising event

blanking is disabled and the blanking counter output is

true, thereby allowing the event signal to pass straight

through to the event trigger circuit.

11.6.3

BLANKING TIME UNCERTAINTY

When the rising and falling sources that trigger the

blanking

counters

are

asynchronous

the

COG_clock, it creates uncertainty in the blanking time.

The maximum uncertainty is equal to one COG_clock

period. Refer to Equation 11-1 and Example 11-2 for

more detail.

11.7

Phase Delay

It is possible to delay the assertion of either or both the

rising event and falling event. This is accomplished by

placing a non-zero value in COGxPHR or COGxPHF

phase

delay

count

respectively

(Register 11-13

and

Refer

Figure 11-5 for COG operation with CCP1 and phase

delay. The delay from the input rising event signal

switching to the actual assertion of the events is

calculated the same as the dead-band and blanking

delays. Please see Equation 11-1.

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