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
001C
001D
001E
001F
0020
0021
0022
0023
0024
07CA
0A20
05C6
0A21
04C6
05A6
0000
04A6
0800
bitlow
clkout
btfss
goto
bsf
goto
bcf
bsf
nop
bcf
retlw
eeprom,do
bitlow
port_b,datin
clkout
port_b,datin
port_b,sclk
port_b,sclk
0
;
;
;
;
;
;
;
check state of data bit
low, goto bitlow
high, set datain high
and clock it
output a logic low
set clock line high
; return clock line low
0025
0026
0212
0031
0027
0028
0029
002A
002B
002C
002D
04CA
06F0
05CA
091C
0370
02F1
0A27
;
;****************************************************************
;
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
call
BITOUT
; transmit 1 bit to serial EE
rlf
txbuf
; rotate txbuf left
decfsz count
; all bits done?
goto
TXLP
; no, do another bit
Mon Jun 06 10:49:06 1994
Page 4
16c5x/7x Cross-Assembler V4.12 Released
Line
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0155
0156
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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
002E
Opcode
0800
002F
0030
0031
0032
0033
0C00
0005
0065
0C80
0006
retlw
0
; yes, jump out
;
;****************************************************************
;
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
0034
0035
0036
0037
0038
0039
003A
090E
0C02
0032
0C00
0030
0925
0C08
; 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
;
movlw
b’00000000'
; get the opcode (00b)
movwf
txbuf
; into the output buffer
call
TX
; and transmit it
movlw
.8
; set # bits to 8
DS00560D-page 8
© 1994 Microchip Technology Inc.
8-106
MICROCHIP [ MICROCHIP TECHNOLOGY ]
