Post by thread:Help with 16C84 data EEPROM

Greetings, I'm trying to use the EEPROM on a PIC 16C84 to store some configuration information. I wrote the following program to test the EEPROM. It should fill the EEPROM with its address location (ie EEPROM @ address 3Fh is loaded with 3Fh) and then read the lower 10 EEPROM addresses and display them on a LCD display connected to the PIC. Unfortuneately it doesn't work. I've also checked the EEPROM with my programmer (PICSPA) which indicates that the EEPROM was not altered by the program. Additionally, I've preprogrammed the 16C84 data EEPROM with the PICSPA and then tried to read it with the same negative results. I've tried everything I can think of to access and test the PIC's data EEPROM. If there is an experienced 16C84 programmer that can find any problems in my code (The offending code follows this plea), I would sure like to know what I'm doing wrong. Thanks, Scott Colson Background: PIC 16C84 operating at 4Mhz using an RC clock. All called routines have been tested seperately and work correctly. The last section of the routine properly reads the EEDATA and EEADR registers, but the EEDATA register always contains the value 01h which is the last value written to it in the previous code section. . . <Removed> . . ; ; Test LCD display ; bsf LOAD ;Enable LCD display movlw DIGIT_P ;Send "P" call SEND_8 movlw DIGIT_H ;Send "H" call SEND_8 movlw $00 ;Send blank call SEND_8 movlw $00 ;Send blank call SEND_8 bcf LOAD ;Disable LCD display call WAIT_250MS ;Wait 1 second call WAIT_250MS call WAIT_250MS call WAIT_250MS ; ; WRITE Data to EEPROM ; movlw $3f ;Set up loop for all 64 bytes movwf REG4 ;of EEPROM ..LOOP: movf REG4,0 ;Get current loop count movwf EEADR ;Copy to EEPROM Address movwf EEDATA ;Copy to EEPROM data bsf RP0 ;Goto register page 1 bsf WREN ;Enable EEPROM write movlw $55 ;Initiate EEPROM write movwf EECON2 movlw $AA movwf EECON2 bsf WR call WAIT_250MS ;Wait for EEPROM write to finish bcf WREN ;Disable EEPROM write bcf RP0 ;Goto register page 0 decfsz REG4,1 ;Decrement loop counter and goto ..LOOP ;repeat loop until done ; ; Read EEPROM and display on LCD ; movlw $09 ;Set up loop count movwf REG4 ..LOOP: movf REG4,0 ;Get current loop count movwf EEADR ;Copy to EEPROM address register bsf RP0 ;Goto register page 1 bsf RD ;Initiate EEPROM read bcf RP0 ;Goto register page 0 bsf LOAD ;Enable LCD Display movf EEDATA,0 ;Get data from EEPROM andlw %00001111 ;Mask off upper nibble call GET_LCD_SGMNTS ;Convert nibble to LCD digit call SEND_8 ;Send it to LCD display movf EEADR,0 ;Get EEPROM address call GET_LCD_SGMNTS ;Convert nibble to LCD digit call SEND_8 ;Send it to LCD display movlw $00 ;Send out two blanks to fill call SEND_8 ;display buffer movlw $00 call SEND_8 bcf LOAD ;Disable LCD display call WAIT_250MS ;Wait 1 second call WAIT_250MS call WAIT_250MS call WAIT_250MS decfsz REG4,1 ;Decrement loop count and goto ..LOOP ;repeat . . <Removed> . . ..WAIT: goto ..WAIT ;Loop continuously

TO: Scott Colson, INTERNET:spam_OUTcolsonsTakeThisOuTIIA.ORG Re: Re:Help with 16C84 data EEPROM >I've tried everything I can think of to access and test the PIC's data >EEPROM. If there is an experienced 16C84 programmer that can find any >problems in my code (The offending code follows this plea), I would sure >like to know what I'm doing wrong. Scott - this code works. It is written in ASPIC. WARNING - ASPIC HANDLES REGISTER BANKING: you will need to add that in your code! This assumes that you have included the segment managemant macros (SEGMACS.ASI), and the default segment definitions in (PICMACRO.ASM). (We first need to generate overriding bit labels for EECON1 bits if we are compiling with 5.32, Registered users with 5.33beta or later need not worry about this) .seg REGS2 ;bank 2 register area .ds 1 OPTION: .ds 1 ;option register OPTINIT_NP = %10001000 ;Option for no PORTB_PULLUP OPTINIT = %00001000 ;default OPTION register ;|||||||| ;|||||||+---- \ ;||||||+----- |- Prescaler exponent ;|||||+------ / ;||||+------- PSA : Prescaler dest - 1=WDT, 0=RTCC ;|||+-------- RTE : RTCC edge - 1=v 0=^ ;||+--------- RTS : RTCC Source 1=EXT 0=INT ;|+---------- INTEDG : INT (RB0) Edge - 1=^ 0=v ;+----------- RBPU : Port B weak pullup enable 0=on .ds 3 ;PCL,STATUS,FSR image TRISA: .ds 1 TRISB: .ds 1 .ds 1 ;(tris C) ;*************************************************************************** ;** EECON1 ;** *** DANGER *** WE NEED TO RE-DEFINE THE EECON1 BITS TO FIX A BUG IN ;** ASPIC 5.32! **DO NOT USE THE INTERNAL DEFINITIONS!!! ;** ;*************************************************************************** EECON1: B.RD = 0,* ;EEPROM READ B.WR = 1,* ;EEPROM WRITE B.WREN = 2,* ;WRITE ENABLE B.WRERR = 3,* ;Write error flag B.EEIF = 4,* ;EE write complete interrupt flag .ds 1 ;EECON1 .seg CODE ;general code area ;*************************************************************************** ;** EE_READ - read EEPROM address in W ;** Return the contents of the EEPROM location in W ;** returns the value in W ;** ;** Data is stored in EEPROM in 1's compliment to increase the 1's density ;** This increases the life of the EEPROM ;** ;** Preserves ALL TEMPS (ASPIC takes care of all of the register banking!) ;** ;*************************************************************************** EE_READ: CLRWDT ;reset watchdog timeout ..loop: BTFSC B.WR ;wait for previous write to end goto ..loop MOVWF EEADR ;set address SEB B.RD CLRWDT MOVFW EEDATA ;get eeprom data XORLW $FF ;flip bits return ;w=EEPROM DATA ;*************************************************************************** ;** EE_WRITE - Write W to the EEPROM location in TEMP ;** ;** returns the value in W ;** ;** Data is stored in EEPROM in 1's compliment to increase the 1's density ;** This increases the life of the EEPROM ;** ;** The location is read first and is not written if the contents have not ;** changed. ;** ;** Preserves W and all TEMPS ;** ;*************************************************************************** EE_WRITE: CLRWDT ;reset watchdog timeout ..loop: ; BTFSC B.WR ;wait for previous write to end goto ..loop; ; MOVWF EEDATA ;set data MOVFW TEMP ; MOVWF EEADR ;set address MOVFW EEDATA ;GET data back SEB B.RD ;initiate READ XORLW $FF ;flip bits to improve endurance XORWF EEDATA ;CHECK if data is the same BZ eew_x ;data is the same, don't write MOVWF EEDATA ;set data to write SEB B.WREN ;make sure write is enabled movlw $55 ;** MAGIC NUMBER FOR EE WRITE clb GIE ;disable interrupts movwf EECON2 ;\****************************** movlw $AA ; \ MAGIC CODE movwf EECON2 ; / DO NOT CHANGE bsf B.WR ;/****************************** movfw EEDATA ;restore W eew_x: XORLW $FF ;flip bits retfie ;RETURN and re-enable INTS - Don