Using the 93LC56 and 93LC66
0125
0126
0127
0128
0129
0130
0131
0132
0133
0134
0135
0136
0137
0138
0139
0140
0141
0142
0143
0144
0145
0146
0147
0148
0149
0150
0151
0152
0153
;
BITOUT routine
;
This routine takes one bit of data in ‘do’ and
;
transmits it to the serial EE device
;*************************************************************
BITOUT
btfss
eeprom,do
; check state of data bit
goto
bitlow
; low, goto bitlow
bsf
port_b,datin
; high, set datain high
goto
clkout
; and clock it
;
bitlow
bcf
port_b,datin
; output a logic low
clkout
bsf
port_b,sclk
; set clock line high
nop
bcf
port_b,sclk
; return clock line low
retlw
0
;
;****************************************************************
;
Transmit Data Subroutine
;
This routine takes the byte of data stored in the
;
‘datao’ register and transmits it to the serial EE device.
;****************************************************************
TX
movf
bits,w
; set the number of bits to xmit
movwf
count
;
TXLP
bcf
eeprom,do
; assume bit 7 is low
btfsc
txbuf,7
; is bit 7 clear?
bsf
eeprom,do
; no, set data bit =1
Mon Jun 06 10:49:00 1994
Page 4
0013
0014
0015
0016
0017
0018
0019
001A
001B
07CA
0A17
05C6
0A18
04C6
05A6
0000
04A6
0800
001C
001D
0212
0031
001E
001F
0020
04CA
06F0
05CA
16c5x/7x Cross-Assembler V4.12 Released
Line
0154
0155
0156
0157
0158
0159
0160
0161
0162
0163
0164
0165
0166
0167
0168
0169
0170
0171
0172
0173
0174
0175
0176
0177
0178
0179
0180
0181
0182
0183
0184
0185
0186
0187
0188
PC
0021
0022
0023
0024
0025
Opcode
0913
0370
02F1
0A1E
0800
call
rlf
decfsz
goto
retlw
BITOUT
txbuf
count
TXLP
0
;
;
;
;
;
transmit 1 bit to serial EE
rotate txbuf left
all bits done?
no, do another bit
yes, jump out
0026
0027
0028
0029
002A
0C00
0005
0065
0C80
0006
;
;****************************************************************
;
POWER-UP ROUTINE
;
This is the program entry point, which in this case simply
;
sets the port_a I/O lines and directs control to the
;
erase/write enable routine.
;*****************************************************************
PWRUP
;
movlw
b’00000000'
tris
port_a
; set port_a as all output
clrf
port_a
; all lines low
movlw
tris
b’10000000'
port_b
8
002B
002C
002D
0907
0C02
0032
; set RB7 as input, rest output;
;
;
Fall through and do erase/write enable
;
;****************************************************************
;
EWEN (Erase/Write ENable Routine)
;
this routine enables the dut for erasing and
;
writing. This must be done prior to any erase,write
;
eral,wral instructions.
;****************************************************************
EWEN
;
call
BSTART
; generate a start bit
;
movlw
.2
; set # bits to 2
movwf
bits
;
© 1994 Microchip Technology Inc.
DS00560D-page 13
8-111
MICROCHIP [ MICROCHIP TECHNOLOGY ]
