导航:PIC单片机的读写93XCXX程序
TITLE "R/W EEPROM"
LIST P = 16C54
;Serial Eprom interface to PIC16C5X.
;REV 2.0 8/26/92.
;
;Define Equates:
;
PIC54 EQU 1FFH
;
PAGE
;
ORG 0
START
goto main ;run test program
;
PAGE
;
TRUE EQU 1
FALSE EQU 0
S93C46 EQU FALSE
S93LC46 EQU FALSE
S93C56 EQU FALSE
S93LC56 EQU FALSE
S93C66 EQU TRUE
S93LC66 EQU FALSE
wire3 equ TRUE
org8 EQU FALSE
;
IF S93LC46
IF org8
LC468 EQU TRUE
XC46 EQU FALSE
H16 EQU FALSE
H8 EQU FALSE
ELSE
LC468 EQU FALSE
XC46 EQU TRUE
H16 EQU FALSE
H8 EQU FALSE
ENDIF
ELSE
ENDIF
IF S93C46
LC468 EQU FALSE
XC46 EQU TRUE
H16 EQU FALSE
H8 EQU FALSE
ENDIF
IF S93C56 + S93C66 + S93LC56 + S93LC66
IF org8
H8 EQU TRUE
H16 EQU FALSE
LC468 EQU FALSE
XC46 EQU FALSE
ELSE
H16 EQU TRUE
H8 EQU FALSE
LC468 EQU FALSE
XC46 EQU FALSE
ENDIF
ELSE
ENDIF
;********************************************************************
;* Register Assignments *
;********************************************************************
indir equ 0 ;Use this register as source/destination
;for indirect addressing.
pc equ 2 ;PIC Program Counter.
status equ 3 ;PIC Status Register.
fsr equ 4 ;File Select Register.
serial equ 5 ;Port used for 93CX6 control.
;The following four registers must be
;located consecutively in memory.
cmd equ 1a ;This register contains the 4 bit
;command op code for 93CX6 as follows:
;bit 7 msb of command op code
;bit 6 next bit of op code
;bit 5 next bit of op code
;bit 4 lsb of op code
;bit 3 A8 of address in case of
;56/66 in 8 bit mode.
addr equ 1b ;memory address of lower 7/8 bits
highb equ 1c ;Used in read/write routines to store the
;upper byte of a 16 bit data word,
;or the data in a 8 bit data word
lowb equ 1d ;Used in read/write routines to store the
;lower byte of a 16 bit data word,
;or not used in 8 bit data word.
cnthi equ 1e ;Used as the upper byte of a sixteen bit
;loop counter in RDYCHK routine.
cnt equ 1f ;Used as the lower byte of a sixteen bit
;loop counter in RDYCHK routine, and
;elswhere as an eight bit counter.
temp_cmd equ 1e ;doubles as a temp register for cmd
temp_addr equ 1f ;doubles as a temp register for addr
;********************************************************************
;* Bit Assignments *
;********************************************************************
carry equ 0 ;Carry Flag of Status Register.
zflag equ 2 ;Zero Flag of Status Register.
cs equ 2 ;Port pin tied to CS on 93CX6.
din equ 1 ;Port pin tied to DI on 93CX6.
dout equ 1 ;Port pin tied to DO on 93CX6.
clock equ 3 ;Port pin tied to CLK on 93CX6.
;********************************************************************
;* General Assignments *
;********************************************************************
no_err equ 0
error equ 1
tries equ 20 ;After issuing a WRITE, ERASE, ERAL, or WRAL
;command, the approximate number of machine
;cycles X 256 to wait for the RDY status.
;This value must be adjusted for operating
;frequencies other than 4 MHz.
read equ b''10000000'' ;read command op code
write equ b''01000000'' ;write command op code
erase equ b''11000000'' ;erase command op code
ewen equ b''00110000'' ;erase enable command op code
ewds equ b''00000000'' ;erase disable command op code
eral equ b''00100000'' ;erase all command op code
wral equ b''00010000'' ;write all command op code
;********************************************************************
;* Macro Definitions *
;********************************************************************
sel MACRO ;Selects the 93CX6 device.
bsf serial,cs ;Chip Select (CS) = ''1'' to select
ENDM ;the device
dsel MACRO ;De-select the 93CX6 device.
bcf serial,cs ;Chip Select (CS) = ''0'' to de-select
;the device.
ENDM
strtbt MACRO ;Issue the Start Bit to the 93CX6.
bsf serial,din ;Start Bit = ''1''.
clkit ;Clock it out.
ENDM
clkit MACRO ;Clocks a serial data bit into or out
;of the 93CX6 device.
bsf serial,clock ;Clock (CLK) = ''1''.
nop ;Adjust the number of nop instructions
;between the assertion and de-assertion of
;CLK in proportion to the PIC operating
;frequency. Refer to the 93CX6 data for the
;minimum CLK period.
bcf serial,clock ;Clock (CLK) = ''0''.
ENDM
;
PAGE
;********************************************************************
;* DOUTx *
;********************************************************************
;doutxx, outputs up to 11 bits of op code/data, depending on whether
;a 46/56/66 serial eeprom is being used. The number of bits over 8 are
;saved in the cmd register and the rest in the addr register. Before
;calling this routine the cmd and the addr registers should be loaded
;as follows:
;cmd reg.bits 7|6|5|4|3|2|1|0
;--------------|-|-|-|-|-|-|-|
; X|X|X|X|X|X|X|Y| --> not used
; X|X|X|X|X|X|Y|X| --> mot used
; X|X|X|X|X|Y|X|X| --> not used
; X|X|X|X|Y|X|X|X| --> 9th bit of address if necessary
; X|X|X|Y|X|X|X|X| --> lsb of command op code
; X|X|Y|X|X|X|X|X| --> 3rd bit of command op code
; X|Y|X|X|X|X|X|X| --> 2nd bit of command op code
; Y|X|X|X|X|X|X|X| --> msb of command op code
;
;addr reg. 6/7/8 bits of address if necessary.
IF H8
dout11
bcf serial,din
rlf indir ;rotate thru carry
btfsc status,carry ;set?
bsf serial,din ;yes, set output to 1
clkit ;clk data
ENDIF
IF H16+H8
dout10
rlf indir ;rotate thru carry
bcf serial,din ;set output to 0
btfsc status,carry ;set?
bsf serial,din ;else set output to 1
clkit ;clk data
ENDIF
IF H8+H16+LC468
dout9
rlf indir ;rotate thru carry
bcf serial,din ;set output to 0
btfsc status,carry ;set?
bsf serial,din ;else set output to 1
clkit ;clk data
incf fsr ;inc pointer
ENDIF
dout8
movlw 8 ;Initialize loop counter.
movwf cnt
;
d_o_8 bcf serial,din ;Assume that the bit to be transfered is a
;''0''. Hence, de-assert DI.
rlf indir ;Rotate the actual bit to be transferred into
;the carry bit.
btfsc status,carry ;Test the carry, if our assumption was
;correct, skip the next instruction.
bsf serial,din ;No, actual bit was a ''1''. Assert DI.
clkit ;Clock the 93CX6.
decfsz cnt ;Repeat until cnt = 0.
goto d_o_8 ;Cnt still > 0.
rlf indir ;Restore register to its original condition.
bcf serial,din ;make sure din is low
retlw no_err ;Exit with good status.
;********************************************************************
;* DIN8 *
;********************************************************************
;Din8 will input 8 bits of data from the
;93CX6. Before calling this routine, the FSR
;must point to the register being used to
;hold the incomming data.
din8
IF wire3
;set up the RA1 as a input before proceeding
movlw b''00000010'' ;set up porta
tris serial ;
ENDIF
movlw 8 ;Initialize loop counter.
movwf cnt ;
d_i_8
rlf indir ;Make room for the incomming bit in the
;destination register.
bcf indir,0 ;Assume that the incomming bit is a ''0'' and
;clear the LSB of the destination register.
clkit ;Clock a bit in the 93CX6.
btfsc serial,dout ;Test the incomming bit, if our assumption
;was correct, skip the next instruction.
bsf indir,0 ;No, actual bit is a ''1''. Set the LSB of the
;destination register.
decfsz cnt ;Repeat until cnt = 0.
goto d_i_8 ;Cnt still > 0.
IF wire3
;setup RA1 back to output
movlw 0 ;set RA1 as output
tris serial ; /
ENDIF
retlw no_err ;Exit with good status.
;********************************************************************
;* RDYCHK *
;********************************************************************
;Rdychk will read the 93CX6 READY/BUSY status
;and wait for RDY status within the alloted
;number of processor cycles. If RDY status
;is not present after this set period, the
;routine will return with an error status.
rdychk
IF wire3
;set up RA1 as a input before proceeding
movlw b''00000010'' ;set up porta
tris serial ;
ENDIF
movlw tries ;Initialize time-out counter.
movwf cnthi ;
clrf cnt ;
dsel ;De-select the 93CX6.
; nop ;NOTE: Check the 93CX6 data sheet for
;minimum CS low time. Depending upon
;processor frequency, a nop(s) may be
;between the assertion and de-assertion of
;Chip Select.
sel ;Re-select the 93CX6.
notrdy btfsc serial,dout ;If DO is a ''0'', 93CX6 has yet to completed
;the last operation (still busy).
goto rdynoerr ;skip to no error
decfsz cnt ;No, not yet ready. Decrement the LSB of our
;16 bit timer and check for expiration.
goto notrdy ;Still some time left. Try again.
decfsz cnthi ;Least significant byte expired - decrement
;and check for expiration of the MSB.
goto notrdy ;Still some time left. Try again.
IF wire3
;setup RA1 back to output
movlw 0 ;set RA1 as output
tris serial ; /
ENDIF
retlw error ;RDY status was not present in the alloted
;time, return with error status.
rdynoerr
IF wire3
;setup RA1 back to output
movlw 0 ;set porta as output
tris serial ; /
ENDIF
retlw no_err
;********************************************************************
;* SEE *
;********************************************************************
;See will control the entire operation of a
;93CX6 device. Prior to calling the routine,
;load a valid command/memory address into
;location cmd, and for WRITE or WRAL
;commands, load registers highb and lowb with
;16 bits of write data. Upon exit, the W
;register will contain the completion status.
;Only 93CX6 instructions which require a
;status check can return with an error as the
;completion status. The values that denote
;the completion status are defined as
;variables ''error'' and ''no_err'' in the
;general assignments section.
see
movf cmd,w ;save cmd
movwf temp_cmd
movf addr,w ;save addr
movwf temp_addr ;
movlw cmd ;Load W with the location of the cmd
;register.
movwf fsr ;Transfer that information into the File
;Select Register. The fsr now points to
;location cmd.
sel ;Select the 93CX6.
strtbt ;Send a start bit.
;
btfsc cmd,7 ;bit 7 = 0?
IF XC46
goto sca8 ;xfer 8 bit cmd/adr
ENDIF
IF LC468
goto sca9 ;xfer 9 bit cmd/adr
ENDIF
IF H16
goto sca10 ;xfer 10 bit cmd/adr
ENDIF
IF H8
goto sca11 ;xfer 11 bit cmd/adr
ENDIF
; goto set_cmd_addr ;no then set cmd/addr
btfss cmd,6 ;bit 6 = 0 ?
IF XC46
goto sc8 ;xfer 8 bit cmd/adr
ENDIF
IF LC468
goto sc9 ;xfer 9 bit cmd/adr
ENDIF
IF H16
goto sc10 ;xfer 10 bit cmd/adr
ENDIF
IF H8
goto sc11 ;xfer 11 bit cmd/adr
ENDIF
; goto set_cmd ;yes then set cmd
IF XC46
goto sca8 ;xfer 8 bit cmd/adr
ENDIF
IF LC468
goto sca9 ;xfer 9 bit cmd/adr
ENDIF
IF H16
goto sca10 ;xfer 10 bit cmd/adr
ENDIF
IF H8
goto sca11 ;xfer 11 bit cmd/adr
ENDIF
; goto set_cmd_addr ;else set cmd/addr
see1
movf temp_cmd,w ;retore cmd
movwf cmd ; /
movf temp_addr,w ;restore addr
movwf addr ; /
btfsc cmd,6 ;Check for a WRITE or ERASE command.
goto see2 ;Yes, parse the command further.
btfsc cmd,7 ;Check for a READ command.
goto read_ ;Yes, process READ command.
btfsc cmd,5 ;Check for a EWEN or ERAL command.
goto see3 ;Yes, parse the command further.
btfsc cmd,4 ;Check for a WRAL command.
goto write_ ;Yes, process WRITE/WRAL command.
exit_ dsel ;No further processing required; 93CX6
;command completed.
;
retlw no_err ;Return with good completion status.
see2 btfss cmd,7 ;Check for a ERASE command.
goto write_ ;No, process WRITE command.
exit2_ call rdychk ;ERASE command requires a status check.
dsel ;De-select the 93CX6.
addwf pc ;Compute completion status from results of
;status check.
retlw no_err ;Return with good completion status.
retlw error ;Return with bad completion status.
see3 btfsc cmd,4 ;Check for a EWEN command.
goto exit_ ;Yes, no further processing required, exit
;now.
goto exit2_ ;No, ERAL command which requires a status
;check.
read_ incf fsr ;Increment the File Select Register to point
;to the register receiving the upper byte of
;the incomming 93CX6 data word.
call din8 ;Input the upper byte.
IF org8
ELSE
incf fsr ;Increment the File Select Register to point
;to the register receiving the lower byte.
call din8 ;Input 8 more bits.
ENDIF
goto exit_ ;No further processing required, exit now.
write_ incf fsr ;Increment the File Select Register to point
;to the upper byte of the 16 bit 93CX6 data
;word to be transmitted.
call dout8 ;Output that byte.
IF org8
ELSE
incf fsr ;Increment the File Select Register to point
;to the lower byte.
call dout8 ;Output the lower byte of the 16 bit 93CX6
;data word.
ENDIF
goto exit2_ ;Exit with a status check.
;
;
IF XC46
sca8
movlw b''11000000'' ;clr all but hi 2
andwf cmd,w ;save in w
iorwf addr ;mask in addr.
incf fsr ;inc FSR
call dout8 ;output
goto see1 ;return
ENDIF
IF LC468
;
sca9
bcf addr,7 ;clr hi of addr
btfsc cmd,6 ;xfer cmd''s bit 6
bsf addr,7 ;to addr''s bit 7
call dout9 ;output
goto see1 ;return
ENDIF
IF H16
;
sca10
call dout10 ;output cmd reg
goto see1 ;return
ENDIF
;
IF H8
sca11
bcf cmd,5 ;xfer cmd''s bit 3 to
btfsc cmd,3 ;cmd''s bit 5
bsf cmd,5 ; /
call dout11 ;output
goto see1 ;return
;
ENDIF
;
;
;
IF XC46
sc8
movf cmd,w ;get command
movwf addr ;save in addr
incf fsr ;inc pointer
call dout8 ;output
goto see1 ;return
;
ENDIF
IF LC468
sc9
rlf cmd,w ;rotate cmd left
movwf addr ;save in addr
call dout9 ;xfer 9 bits
goto see1 ;return
ENDIF
IF H16
;
sc10
rlf cmd ;rotate cmd
rlf cmd,w ;left twice
movwf addr ;save in addr
clrf cmd ;clear command
call dout10 ;xfer 10 bits
goto see1 ;return
ENDIF
;
IF H8
sc11
bcf addr,7 ;xfer cmd''s bit 4
btfsc cmd,4 ;to addr''s bit 7
bsf addr,7 ; /
call dout11 ;xfer 11 bits
goto see1 ;return
ENDIF
;********************************************************************
;* Test Program *
;********************************************************************
main ;We''ve include a sample program to exercise
;the PIC to 93C66 interface using a simple
;erase, write and verify routine.
;8 bit organization has been used
;with a 3 wire interface.
clrf serial ;Clear the port tied to the 93C66 device.
movlw b''11110000'' ;Intialize the data direction register for
tris serial ;that port.
movlw ewen ;Load W with the Erase/Write Enable command.
movwf cmd ;Transfer W into cmd register.
call see ;Enable the 93C66 device.
movlw eral ;Load W with the Erase All command.
movwf cmd ;Transfer W into cmd register.
call see ;Erase the 93C66.
xorlw error ;Check completion status.
btfsc status, zflag ;Test for error condition.
goto errloop ;Yes, bad completion status, error-out.
;Write loop:
tstptrn equ 0xAA ;Define the test pattern to be written.
movlw write ;Load W with the Write command.
movwf cmd ;Transfer W into cmd register.
movlw tstptrn ;Intialize the 93C66 data registers with
;write data.
movwf highb ;load in high byte only
;since 8 bit low byte is ignored
clrf addr ;start at addr 0
test1 call see ;Write data word into 93C66 device.
xorlw error ;Check completion status.
btfsc status,zflag ;Test for error condition.
goto errloop ;Yes, bad completion status, error-out.
incfsz addr ;No, increment the 8 bit memory address
;field.
goto test1 ;write another location
btfss cmd,3 ;see if all done
goto wrt_nxt_pg ;no then write next page
goto read_tst ;read written data
wrt_nxt_pg
bsf cmd,3 ;set page bit
goto test1 ;No, write another location.
;Read loop:
read_tst
movlw read ;Load W with the Read command.
movwf cmd ;Transfer W into cmd register.
test2 call see ;Read addressed data word from 93C66 device.
movlw tstptrn ;Load W with the pattern written.
subwf highb,w ;Verify the data read against what was
;written.
btfss status,zflag ;Same?
goto errloop ;No, error-out.
incfsz addr ;Yes, both byte correct, increment the 8 bit
;memory address field.
goto test2 ;do next byte
btfss cmd,3 ;check page bit
goto rd_nxt_pg ;no then chk next page
goto allok ;all done!!!
rd_nxt_pg
bsf cmd,3 ;set page bit
goto test2 ;No, read another location.
allok goto allok ;Home safe!
;
;
errloop
goto errloop
;
;
;
;KEY DEFINITIONS
;
ORG PIC54
SYS_RESET
GOTO START
;
END