18F1320 ... Strange Memory

[Melanie]

I've studied two chips...

Both have a Batch Code of 05250SE and a Silicon Revision of DEVID2=07h DEVID1=C4h (located at 3FFFFEh and 3FFFFFh respectively).

This is my Test Code, run on internal Oscillator at 4 and then at 8MHz... compiled with PBP2.46 with patches and MPASM 5.01.

	'
	'	EEPROM Test Program for PIC18F1320
	'	----------------------------------
	'	Melanie
	'	07/04/2006
	'	----------

	'
	'	PIC Defines
	'	-----------
	@ __CONFIG  _CONFIG1H, _IESO_OFF_1H & _FSCM_OFF_1H & _INTIO1_OSC_1H
	@ __CONFIG  _CONFIG2L, _PWRT_ON_2L & _BOR_OFF_2L & _BORV_20_2L
	@ __CONFIG  _CONFIG2H, _WDT_ON_2H & _WDTPS_32K_2H
	@ __CONFIG  _CONFIG3H, _MCLRE_OFF_3H
	@ __CONFIG  _CONFIG4L, _DEBUG_OFF_4L & _LVP_OFF_4L & _STVR_ON_4L

	@ __CONFIG  _CONFIG5L, _CP0_OFF_5L & _CP1_OFF_5L
	@ __CONFIG  _CONFIG5H, _CPB_OFF_5H & _CPD_OFF_5H
	@ __CONFIG  _CONFIG6L, _WRT0_OFF_6L & _WRT1_OFF_6L
	@ __CONFIG  _CONFIG6H, _WRTC_OFF_6H & _WRTB_OFF_6H & _WRTD_OFF_6H
	@ __CONFIG  _CONFIG7L, _EBTR0_OFF_7L & _EBTR1_OFF_7L
	@ __CONFIG  _CONFIG7H, _EBTRB_OFF_7H

	'
	'	Hardware Defines
	'	================
		'
		'	PIC Speed
		'	---------
	Define OSC 8

		'
		' 	LCD Display
		'	-----------
	Define LCD_DREG PORTB				' Port for LCD Data
	Define LCD_DBIT 4				' Use upper 4 bits of Port
	Define LCD_RSREG PORTB				' Port for RegisterSelect (RS) bit
	Define LCD_RSBIT 3				' Port Pin for RS bit
	Define LCD_EREG PORTB				' Port for Enable (E) bit
	Define LCD_EBIT 2				' Port Pin for E bit
	Define LCB_BITS 4				' Using 4-bit bus
	Define LCD_LINES 2				' Using 2 line Display
	Define LCD_COMMANDUS 2000			' Command Delay (uS)
	Define LCD_DATAUS 50				' Data Delay (uS)
		'
		'	Other Ports
		'	-----------
	LED var PortB.0	

	'
	'	Software Defines
	'	----------------
	CounterA var BYTE				' Just a Counter
	DataA var BYTE					' Byte Variable for Data
	DataB var BYTE
	EEPROMError var BIT				' Error Flag

	'
	'	EEPROM Presets
	'	--------------
	Data @0,"This is a Test String that should be overwritten"
	Data	"by the Write to EEPROM routine"

	'
	'	Start Program Here
	'	==================

	'
	'	Initalise PIC
	'	-------------
	OSCCON=%01110010
	ADCON1=%01111111
	TRISB=%00000000
	Low LED
	Pause 2000
	High LED

	'
	'	Write to EEPROM
	'	---------------
	LCDOut $FE,1,"Writing EEPROM",$FE,$C0,"A="
	For CounterA=0 to 255
		DataA=255-CounterA
		LCDOut $FE,$C2,#CounterA
		Write CounterA,DataA
		Next CounterA
	LCDOut $FE,1,"Write Complete"
	Pause 2000

	'
	'	Read & Verify EEPROM
	'	--------------------
	EEPROMError=0
	LCDOut $FE,1,"Verifying EEPROM",$FE,$C0,"A="
	For CounterA=0 to 255
		LCDOut $FE,$C2,#CounterA
		Read CounterA,DataA
		DataB=255-CounterA
		If DataA<>DataB then
			LCDOut $FE,$C6,"E=",HEX2 DataB
			LCDOut $FE,$CB,"R=",HEX2 DataA
			EEPROMError=1
			Pause 2000
			LCDOut $FE,$C6,REP 32\11
			endif
		Next CounterA
	LCDOut $FE,1,"Write Complete"

	'
	'	Result
	'	------
	LCDOut $FE,$C0,"Chip Test "
	If EEPROMError=0 then
		LCDOut "Pass"
		else
		LCDOut "Fail"
		endif

EndLoop:
	Pause 500
	Toggle LED
	Goto EndLoop

	end

And the result?

One chip fails miserably, and the other works perfectly. The appended picture shows the good PIC passing at 8MHz... frequency counter is measuring Internal Oscillator OUT on RA6 which is fosc/4.

The PIC that failed did NOT write to EEPROM... it's previous contents were untouched, the Read section reported $FF from every memory Location (that had not previously been preset by a DATA statement). I have not had time to impliment the ERRATA (Section 10 Page 3) suggestions from Microchip and verify if the dud PIC works with one or both of them.

Alain, email or message me your address off-list and I'll send you the working PIC - you can then see if your program works on that.