Interfacing X84041 EEPROM Motorola 68HC11 Microcontroller This ap

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Interfacing X84041 EEPROM Motorola 68HC11 Microcontroller This ap

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AN100
Interfacing X84041 EEPROM Motorola 68HC11 Microcontroller
This application note demonstrates Xicor X84041 EEPROM interfaced 68HC11 microcontroller family when connected shown Fig. interface uses time-multiplexed address/data control lines 68HC11 interface EEPROM. Although X84041 requires minimal glue logic 3-NAND gates when connected 68HC11, advantage EEPROM port-less serial memory device still preserved. 68HC11 assembly code listing this application note obtained from Xicor BBS, FaxBack system, Xicor's site http://www.xicor.com
RESET XIRQ
A15/PB7 A14/PB6 A13/PB5 A12/PB4 A11/PB3 A10/PB2 A9/PB1 A8/PB0 AD7/PC7 AD6/PC6 AD5/PC5 AD4/PC4 AD3/PC3 AD2/PC2 AD1/PC1 AD0/PC0
74HT138
X84129
74CT100 68HC11A8
Figure Typical hardware connection interfacing X84041 68HC11 microcontroller.
April Rev.
Xicor, Inc. 1511 Buckeye Drive Milpitas, 95035 (408) 432-8888
AN100-1
AN100
DESCRIPTION: This file contains general utility routines written 68HC11 assembly language used interface 68HC11 XICOR X84041 EEPROM. interface uses 68HC11 parallel control lines connect X84041. microcontroller control lines connected through NAND gates match control lines. Address lines A15, A14, decoded chip select; mapping X84041 address space 6000: 7FFF. following table lists subroutines this file with brief description: ResetD: Resets device before read write take place Page_Write: Writes page data device Page_Read: Reads page data from device into Byte_Read: Reads byte data from device into Byte_Write: Writes byte data device Inbyte: Called read subroutines shit data Outbyte: Called write subroutines shit data Sndaddr: Called read/write subroutines send address device SNVWrte: Provides start non-volatile write sequence required writes CheckNVW: Checks makes sure non-volatile write completed Main program writes test string into EEPROM. After page programmed, first byte page altered. page then read back written different location memory. data read temporarily stored internal RAM.
INTERNAL RAMBASE $0000 INTERNAL BASE ADDRESS(Default) RAMBuff RAMBASE BUFFER ADDRESS STACK RAMBASE+$FF PROGRAM CONSTANTS Address $6000 MPSaddress $0000 MPSaddress2 $0100 Page_Size RESET VECTOR ENTRY POINT $FFFE $E000 RESET VECTOR ADDRESS PROGRAM ENTRY JUMP BEGINNING EXECUTABLE
ASSEMBLER REQUIREMENT- TYPE P68H11
Xicor
AN100
START USER CODE $E000 MAIN: #STACK LOAD STACK POINTER
INITIALIZE BUFFER BEFORE PROGRAMMING CONTENT SECTOR #TestString Test String Address #MPSaddress Address within write data Page_Write Write data first page #MPSaddress Address within write byte Byte_Write Write byte first address location #MPSaddress Address within read from Page_Read Read data first page #RAMBuff data pointer data just read #MPSaddress2 Address within write data Page_Write Write data page 0100 Done: Done Name: resetd Description: Sends Reset sequence device. Function: Performs read, write "0", read Calls: Input: Output: Register Usage: ResetD: ldaa Address sends read command clra clear accum staa Address send write command ldaa Address sends read command Name: Page_Write Description: Function: Writes page data first address. Calls: Sndaddr, OutByte Input: Output: Register Usage: Page_Write: Sndaddr Send Page address device #Page_Size register contains number bytes/page PagePW: ldaa Load "test string" register pshy OutByte Sends byte accum puly Increments register Decrements page counter PagePW Branches until bytes written SNVWrte Start Nonvolatile Write CheckNVW Checks completion non-volatile write
AN100-3
Xicor
AN100
Name: Page_Read Description: Function: Reads page data from first address. Calls: Sndaddr, InByte Input: Output: Register Usage: Page_Read: Sndaddr Send Page address device #Page_Size register contains number bytes/page #RAMBuff Sets index register PagePR: pshy InByte Receives byte data puly staa Stores byte Increments register Decrements page counter PagePR Branches until bytes read Name: Byte_Read Description: Function: Reads byte data from first address. Calls: Sndaddr, InByte Input: Output: Register Usage: Byte_Read: Sndaddr Send Byte address device #RAMBuff Sets index register PageBR: InByte Receives byte data staa Stores byte Name: InByte Description: Reads bits Function: Calls: Input: Output: Register Usage: InByte: Sets clra Clears accum out2: ldab Address Load from device accum andb #00000001b Mask-out unwanted bits accum rola Rotate accum left Mask accum into accum out2 Branch until accum contains complete byte
AN100-4
Xicor
AN100
Name: Byte_Write Description: Function: Writes byte data first address. Calls: Sndaddr, OutByte Input: Output: Register Usage: Byte_Write: Sndaddr Send Byte address device ldaa #$58 Load accum with OutByte Send SNVWrte Start Nonvolatile Write CheckNVW Checks completion non-volatile write Name: Sndaddr Description: Send address device Function: Writes address device. Calls: ResetD, Outbyte Input: Output: Register Usage: Sndaddr: ResetD Send reset signal xgdy Load address double accum OutByte send address transfer accum OutByte send address Name: OutByte Description: Function: Sends bits Address. Calls: Input: Output: Register Usage: OutByte: rola out1: rola staa Address out1
AN100-5
Xicor
AN100
Name: SNVWrte Description: Function: Sends bits Address. Calls: Input: Output: Register Usage: SNVWrte: ldaa Address sends read command ldaa accum staa Address send write command ldaa Address sends read command Name: CheckNVW Description: Function: Calls: Input: Output: Register Usage: CheckNVW:ldaa Address sends read command rora rotate carry CheckNVW loop nonvolatile write occuring TestString: 'xICORMPS' X84041 INTERTERFACE SOURCE CODE
AN100-6

Interfacing X84041 EEPROM Motorola 68HC11 Microcontroller This ap

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