PIC18LF4331 datasheet(166/392 Pages) MICROCHIP

166 / 392 page

PIC18F2331/2431/4331/4431

DS39616D-page 166

 2010 Microchip Technology Inc.

FIGURE 17-11:

QEI MODULE RESET TIMING WITH THE INDEX INPUT

QEB

QEA

UP/DOWN

IC2QEIF

POSCNT(1)

Count (+/-)

+1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1

-1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1

MAXCNT

MAXCNT = 1527

Q4(3)

INDX

Q1(4)

Q1(5)

Position

Counter Load

Forward

Reverse

Note 2

Note 1:

POSCNT register is shown in QEI x4 Update mode (POSCNT increments on every rising and every falling edge of

QEA and QEB input signals).

When an INDX Reset pulse is detected, POSCNT is reset to ‘0’ on the next QEA or QEB edge. POSCNT is set to

MAXCNT when POSCNT = 0 (when decrementing), which occurs on the next QEA or QEB edge. a similar Reset

sequence occurs for the reverse direction, except that the INDX signal is recognized on its falling edge. The Reset

is generated on the next QEA or QEB edge.

IC2QEIF is enabled for one TCY clock cycle.

The position counter is loaded with 0000h (i.e., Reset) on the next QEA or QEB edge when the INDX is high.

The position counter is loaded with a MAXCNT value (e.g., 1527h) on the next QEA or QEB edge following the

INDX falling edge input signal detect).

IC2QEIF must be cleared in software.

Note 6

Q4(3)

PIC18LF4331 Datasheet(PDF) 166 Page - Microchip Technology