ADE7566 datasheet(93/136 Pages) AD

93 / 136 page

Preliminary Technical Data

ADE7566/ADE7569

Rev. PrA | Page 93 of 136

A 96 segment LCD with 4× multiplexing requires 96/4 = 24

segment lines. Sixteen pins, FP0 to FP15, are automatically

dedicated for use as LCD segments. Eight more pins must be

chosen for the LCD function. Because the LCD has 4× multi-

plexing, all four common lines are used. As a result, COM2/FP28

and COM3/FP27 cannot be utilized as segment lines. Based on

the alternate functions of the pins used for FP16 through FP25,

FP16 to F23 are chosen for the seven remaining segment lines.

These pins are enabled for LCD functionality in the LCD

Segment Enable SFR (LCDSEGE, 0x97) and LCD Segment

Enable 2 SFR (LCDSEGE2, 0xED).

To determine contrast setting for this 5 V LCD, Table 76 shows

the BIASLVL[5:0] setting that corresponds to a VC of 5 V in

1/3 bias mode. The nominal bias level setting for this LCD is

BIASLVL[5:0] = [111111].

The LCD is setup with the following 8052 code:

; setup LCD pins to have LCD functionality

MOV

LCDSEG, # FP20EN+FP21EN+FP22EN+FP23EN

MOV

LCDSEGX, #FP16EN+FP17EN+FP18EN+FP19EN

; setup LCDCON for fLCDCLK=2048Hz, 1/3 bias and 4x multiplexing

MOV

LCDCON, #BIAS+LMUX1+LMUX0

; setup LCDCONX for charge pump and BIASLVL[1110111]

MOV

LCDCONX, #BIASLVL5+BIASLVL4+BIASLVL3+ BIASLVL2+BIASLVL1+BIASLVL0

; set up refresh rate for 64Hz with fLCDCLK=2048Hz

MOV

LCDCLK, #FD3+FD2+FD1+FD0

; set up LCD data registers with data to be displayed using

; LCDPTR and LCDDATA registers

; turn all segments on FP25 ON and FP26 OFF

ORL

LCDCONY,#01h

; start data memory refresh

MOV

LCDDAT, #F0H

MOV

LCDPTR, #80h OR 0DH

ANL

LCDCONY,#0FEh ; end of data memory refresh

ORL

LCDCON,#LCDEN ; enable LCD

To setup the same 3.3 V LCD for use with an external resistor ladder:

; setup LCD pins to have LCD functionality

MOV

LCDSEG, #FP20EN+FP21EN+FP22EN+FP23EN

MOV

LCDSEGX, #FP16EN+FP17EN+FP18EN+FP19EN

; setup LCDCON for fLCDCLK=2048Hz, 1/3 bias and 4x multiplexing

MOV

LCDCON, #BIAS+LMUX1+LMUX0

; setup LCDCONX for external resistor ladder

MOV

LCDCONX, #EXTRES