DSPIC30F6010_06 datasheet(83/222 Pages) MICROCHIP

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DS70119E-page 81

dsPIC30F6010

14.4

Programmable Digital Noise

Filters

The digital noise filter section is responsible for reject-

ing noise on the incoming capture or quadrature sig-

nals. Schmitt Trigger inputs and a three-clock cycle

delay filter combine to reject low level noise and large,

short duration noise spikes that typically occur in noise

prone applications, such as a motor system.

The filter ensures that the filtered output signal is not

permitted to change until a stable value has been

registered for three consecutive clock cycles.

For the QEA, QEB and INDX pins, the clock divide fre-

quency for the digital filter is programmed by bits

QECK<2:0> (DFLTCON<6:4>) and are derived from

the base instruction cycle TCY.

To enable the filter output for channels QEA, QEB and

INDX, the QEOUT bit must be ‘1’. The filter network for

all channels is disabled on POR and BOR.

14.5

Alternate 16-bit Timer/Counter

When the QEI module is not configured for the QEI

mode QEIM<2:0> = 001, the module can be configured

as a simple 16-bit timer/counter. The setup and control

of the auxiliary timer is accomplished through the

QEICON SFR register. This timer functions identically

to Timer1. The QEA pin is used as the timer clock input.

When configured as a timer, the POSCNT register

serves as the Timer Count Register and the MAXCNT

period register match occur, the QEI interrupt flag will

be asserted.

The only exception between the general purpose tim-

ers and this timer is the added feature of external Up/

Down input select. When the UPDN pin is asserted

high, the timer will increment up. When the UPDN pin

is asserted low, the timer will be decremented.

The UPDN Control/Status bit (QEICON<11>) can be

used to select the count direction state of the Timer

UPDN = 0, the timer will count down.

In addition, control bit UPDN_SRC (QEICON<0>)

determines whether the timer count direction state is

based on the logic state, written into the UPDN Control/

Status bit (QEICON<11>), or the QEB pin state. When

UPDN_SRC = 1, the timer count direction is controlled

from the QEB pin. Likewise, when UPDN_SRC = 0, the

timer count direction is controlled by the UPDN bit.

14.6

QEI Module Operation During CPU

Sleep Mode

14.6.1

QEI OPERATION DURING CPU

SLEEP MODE

The QEI module will be halted during the CPU Sleep

mode.

14.6.2

TIMER OPERATION DURING CPU

SLEEP MODE

During CPU Sleep mode, the timer will not operate,

because the internal clocks are disabled.

14.7

QEI Module Operation During CPU

Idle Mode

Since the QEI module can function as a quadrature

encoder interface, or as a 16-bit timer, the following

section describes operation of the module in both

modes.

14.7.1

QEI OPERATION DURING CPU IDLE

MODE

When the CPU is placed in the Idle mode, the QEI

module will operate if the QEISIDL bit (QEICON<13>)

= 0. This bit defaults to a logic ‘0’ upon executing POR

and BOR. For halting the QEI module during the CPU

Idle mode, QEISIDL should be set to ‘1’.

Note:

Changing the operational mode (i.e., from

QEI to Timer or vice versa), will not affect

the Timer/Position Count Register

contents.

Note:

This Timer does not support the External

Asynchronous Counter mode of operation.

If using an external clock source, the clock

will automatically be synchronized to the

internal instruction cycle.

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