DS00560D-page 2

© 1994 Microchip Technology Inc.

Using the 93LC56 and 93LC66

16c5x/7x Cross-Assembler V4.12 Released

Mon Jun 06 10:49:10 1994

Page 1

Line

PC

Opcode

0001

LIST P=16C54,c=132

0002

;****************************************************************

0003

;

3-Wire Byte Read Program (80 bytes)

0004

;

0005

;

This program demonstrates how to interface a

0006

;

Microchip PIC16C54 to a 93LC56 or 93LC66 Serial EE

0007

;

device.

This program will read 8 consecutive addresses

0008

;

in the ‘random read’ mode.

This means that the opcode

0009

;

and address for each byte will be sent to the device.

0010

;

This program will repeat forever.

0011

;

0012

;

Another, more efficient method of reading consecutive

0013

;

addresses is called the ‘sequential read’ mode.

This

0014

;

involves sending the opcode and address for the first

0015

;

byte to read, then continuing to provide clocks for the

0016

;

next addresses. The device will automatically increment

0017

;

the address.

An example of the sequential read mode is

0018

;

provided in the ‘3wseqr.asm’ file.

0019

;

0020

;

This program communicates to the serial EE in the

0021

;

x16 mode, and ASSUMES THE USER HAS SET THE ORG PIN

0022

;

ON THE DEVICE TO Vcc.

0023

;

0024

;

Timing is based on using the PIC16C54 in ‘XT’ mode

0025

;

using a 4Mhz crystal.

Clock speeds to the serial EE

0026

;

will be approximately 50 kHz for this setup.

0027

;

0028

;

PIC16C54 to Serial EE Connections:

0029

;

0030

;

PIC16C54

Serial EE

0031

;

——————

——————

0032

;

Pin 10 (RB4) —> Chip Select

0033

;

Pin 11 (RB5) —> Clock

0034

;

Pin 12 (RB6) —> Data In

0035

;

Pin 13 (RB7) —> Data Out

0036

;

ORG = Vcc

0037

;

0038

;************************************************************

0039

;

Register Assignments

0040

;************************************************************

0041

0003

status

equ

3h

; status register

0042

0005

port_a

equ

5h

; port 5 (port_a)

0043

0006

port_b

equ

6h

; port 6 (port b) comm lines to serial EE

0044

000A

eeprom

equ

0ah

; bit buffer

0045

000C

addr

equ

0ch

; address register

0046

000D

datai

equ

0dh

; stored data input reg.

0047

000E

datao

equ

0eh

; stored data output reg.

0048

0010

txbuf

equ

10h

; transmit buffer

0049

0011

count

equ

11h

; bits transmitted so far

0050

0012

bits

equ

12h

; bits to transmit

0051

0013

bytcnt

equ

13h

; byte counter for read routine

16c5x/7x Cross-Assembler V4.12 Released

Mon Jun 06 10:49:10 1994

Page 2

Line

PC

Opcode

0052

0015

loops

equ

15h

; delay loop counter

0053

0016

loops2

equ

16h

; delay loop counter

0054

0017

hbyte

equ

17h

; high byte for input data

0055

0018

lbyte

equ

18h

; low byte for input data

0056

;************************************************************

0057

;

Bit Assignments

0058

;************************************************************

0059

0007

di

equ

7

; eeprom input

0060

0006

do

equ

6

; eeprom output

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