From "Philippe"<sonyede@iway.fr>

On Tue, 7 Nov 1995 John.P.Hollingshead@HAPPY.FIRSTNETHOU.COM wrote:

> Also, I'm looking for some good sources for the displays.  What I
> have in mind, is for using a pic 16c57 for taking the 2of 8 binarie
> from a cd22202e dtmfdecode chip, and outputing to a serial e-prom and
> to output to the display.  It then must be able to access the eeprom
> to get readback buffers.

I already do that, specially to read/write serial EEPROM, I use a 93C46, but
another type can also be driven with this code.

Here is a piece of code to drive EEPROM


;>>>>>> START OF SAMPLE CODE
; This what I do to drive a PLL MC145170 and a 96C46 EEPROM

;******************************************************************************
;   HCK      = PortC.1
;   DATA out = PortC.3
;   DATA in  = PortC.5
;   CS PLL   = PortC.2
;   CS ROM   = PortC.6
;
;----- PLL & EEPROM  Constants

bHCK           equ 1
PEnb           equ 2
REnb           equ 6
bDout          equ 3
bDin           equ 5
bLock          equ 0

;******************************************************************************
; READ Routine for SERIAL EEPROM (96C46 : 64 X 16Bit)
; REGISTER used:
;    Data1         -> $0E
;    Data2         -> $0D
;    Address/Temp  -> $0F
;    EETemp        -> $0A

         org $0600
                   ;76543210
SetDataOut     equ %10110001

EERead:  movlw SetDataOut   ; Set HCK/DOUT/ENB as OUTPUT
         tris  C
         bcf  SPort,bHCK    ; bHCK = 0
         bcf  SPort,REnb    ; REnb = 0    ROM ACCESS disable
         bsf  SPort,PEnb    ; PEnb = 1    PLL ACCESS disable

         bcf  SPort,bDOUT
         bsf  SPort,REnb
         nop
         nop
         bsf  SPort,bHCK
         nop
         nop

         call EEStart
         movf Temp,W        ; GET Address from Temp register
         andlw %00111111    ; it's a 6 bit ADDRESS
         iorlw  %10000000   ; ADD Read INSTRUCTION to the word
         call EERdOut
         call EERdIn
         movf  Data1,W
         movwf Data2
         call EERdIn
         bcf  SPort,REnb    ; REnb = 0    ROM ACCESS disable
         retlw 0

;---------------
EEStart: bcf SPort,bHCK
         bsf SPort,Renb
         bsf SPort,bDOut
         nop
         nop
         nop
         bsf SPort,bHCK
         nop
         nop
         bcf SPort,bHCK
         nop
         retlw 0

;---------------
EERdOut: bsf SPort,Renb
         movwf EETemp
         movlw 8
         movwf Temp
         bcf SPort,bHCK

EERdO_1: bcf SPort,bDOut
         rlf EETemp
         btfsc STATUS,Cy
         bsf SPort,bDOut
         nop
         nop
         bsf SPort,bHCK
         nop
         nop
         nop
         bcf SPort,bHCK
         decfsz Temp
         goto EERdO_1
         retlw 0

;---------------
$BREAK
EERdIn:  bsf SPort,Renb
         movlw 8
         movwf Temp
         bcf SPort,bHCK

EERdI_1: nop
         nop
         bsf SPort,bHCK
         nop
         bcf STATUS,Cy
         btfsc SPort,bDIn
         bsf STATUS,Cy
         rlf Data1
         nop
         bcf SPort,bHCK
         decfsz Temp
         goto EERdI_1
         retlw 0

;******************************************************************************
;******************************************************************************
; ENABLE, DISABLE and WRITE Routine for SERIAL EEPROM (64 X 16Bit)
; REGISTER used:
;    Data1         -> $0E
;    Data2         -> $0D
;    Address/Temp  -> $0F
;    EETemp        -> $0A
;    CounterA      -> $1D
;    CounterB      -> $1E


EEEnable:movlw SetDataOut   ; Set HCK/DOUT/ENB as OUTPUT
         tris  C
         bcf  SPort,bHCK    ; bHCK = 0
         bcf  SPort,REnb    ; REnb = 0    ROM ACCESS disable
         bsf  SPort,PEnb    ; PEnb = 1    PLL ACCESS disable

         bcf  SPort,bDOUT
         bsf  SPort,REnb
         nop
         nop
         bsf  SPort,bHCK
         nop
         nop
         bcf  SPort,bHCK

         call EEStart
         movlw %00110000    ; ENABLE WRITE INSTRUCTION
         call EERdOut
         bcf  SPort,REnb    ; REnb = 0    ROM ACCESS disable
         retlw 0

EEDisable:movlw SetDataOut   ; Set HCK/DOUT/ENB as OUTPUT
         tris  C
         bcf  SPort,bHCK    ; bHCK = 0
         bcf  SPort,REnb    ; REnb = 0    ROM ACCESS disable
         bsf  SPort,PEnb    ; PEnb = 1    PLL ACCESS disable

         call EEStart
         movlw %00000000    ; DISABLE WRITE INSTRUCTION
         call EERdOut
         bcf  SPort,REnb    ; REnb = 0    ROM ACCESS disable
         retlw 0

EEWrite: movlw SetDataOut   ; Set HCK/DOUT/ENB as OUTPUT
         tris  C
         bcf  SPort,bHCK    ; bHCK = 0
         bcf  SPort,REnb    ; REnb = 0    ROM ACCESS disable
         bsf  SPort,PEnb    ; PEnb = 1    PLL ACCESS disable

         call EEStart
         movf Temp,W        ; GET Address from Temp register
         andlw %00111111    ; it's a 5 bit ADDRESS
         iorlw %01000000    ; ADD WRITE INSTRUCTION to the word
         call EERdOut
         movf Data2,W       ; Get the "HIGH WORD"
         call EERdOut
         movf Data1,W       ; Get the "LOW WORD"
         call EERdOut

         bcf  SPort,REnb    ; REnb = 0    ROM ACCESS disable
         nop                ; NOW, waiting for acknowledge
         bsf  SPort,bHCK
         nop
         clrf Temp
         bcf  SPort,bHCK
         nop
         bsf  SPort,REnb
         movlw MaxWriteTime
         movwf CounterA

EEWait_1:bsf SPort,bHCK
         nop
         nop
         btfsc SPort,bDIn
         goto EEWait_2
         nop
         bcf SPort,bHCK
         nop
         decfsz Temp
         goto EEWait_1
         decfsz CounterA
         goto EEWait_1
         bcf  SPort,REnb    ; REnb = 0    ROM ACCESS disable
         retlw 1            ; return "1" there is a problem to write th WORD !!!

EEWait_2:bcf  SPort,bHCK
         bcf  SPort,REnb    ; REnb = 0    ROM ACCESS disable
         retlw 0            ; return "0", OK.

;>>>>>> END OF SAMPLE CODE