Interfacing X84256 E2PROM Motorola 68HC11 Microcontroller This ap

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Interfacing X84256 E2PROM Motorola 68HC11 Microcontroller This ap

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AN130
Interfacing X84256 E2PROM Motorola 68HC11 Microcontroller
This application note demonstrates Xicor X84256 E2PROM interfaced 68HC11 microcontroller family when connected shown Figure interface uses time-multiplexed address/data control lines 68HC11 interface E2PROM. Although X84256 requires minimal glue logic, 3-NAND gates when connected 68HC11, advantage E2PROM portless serial memory device still preserved.
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
X84256
74CT100 68HC11
Figure Typical hardware connection interfacing X84256 68HC11 microcontroller
AN130-1
Xicor
AN130
DESCRIPTION: This file contains general utility routines written 68HC11 assembly language used interface 68HC11 XICOR X84256 E2PROM. interface uses 68HC11 parallel control lines connect X84256 microcontroller control lines connected through NAND gates match control lines. Address lines A15, A14, decoded chip select; mapping X84256 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 E2PROM. After page programmed, first byte page altered. page then read back written different location memory. data read temporarily stored internal RAM. INTERNAL RAMBASE RAMBuff STACK $0000 INTERNAL BASE ADDRESS(Default) RAMBASE BUFFER ADDRESS RAMBASE+$FF
PROGRAM CONSTANTS Address MPSaddress MPSaddress2 Page_Size $6000 $0000 $0100
RESET VECTOR ENTRY POINT $FFFE $E000 RESET VECTOR ADDRESS PROGRAM ENTRY JUMP BEGINNING EXECUTABLE CODE
ASSEMBLER REQUIREMENT- TYPE P68H11
AN130-2
Xicor
AN130
START USER CODE $E000 MAIN: #STACK LOAD STACK POINTER INITIALIZE BUFFER BEFORE PROGRAMMING CONTENT SECTOR Done: #TestString #MPSaddress Page_Write #MPSaddress Byte_Write #MPSaddress Page_Read #RAMBuff #MPSaddress2 Page_Write Done Test String Address Address within write data Write data first page Address within write byte Write byte first address location Address within read from Read data first page data pointer data just read Address within write data Write data page 0100
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
AN130-3
Xicor
AN130
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 Name: Byte_Write Description: Function: Writes byte data first address. Calls: Sndaddr, OutByte Input: Output: Register Usage:
AN130-4
Xicor Byte_Write: ldaa Sndaddr #$58 OutByte SNVWrte CheckNVW Send Byte address device Load accum with Send Start Nonvolatile Write Checks completion non-volatile write
AN130
Name: Sndaddr Description: Send address device Function: Writes address device. Calls: ResetD, Outbyte Input: Output: Register Usage: Sndaddr: xgdy ResetD OutByte OutByte Send Load send transfer send reset signal address double accum address accum address
Name: OutByte Description: Function: Sends bits Address. Calls: Input: Output: Register Usage: OutByte: rola out1: rola staa Address out1 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
AN130-5
Xicor
AN130
Name: CheckNVW Description: Function: Calls: Input: Output: Register Usage: CheckNVW:ldaa sends read command rora rotate carry CheckNVW loop nonvolatile write occuring TestString:
X84256 INTERTERFACE SOURCE CODE
AN130-6

Interfacing X84256 E2PROM Motorola 68HC11 Microcontroller This ap

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