Interfacing X84641/129 E2PROM 8051 Microcontrollers E2PROM attrac
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AN107
Interfacing X84641/129 E2PROM 8051 Microcontrollers
E2PROM attractive alternative 'add-on' parallel serial nonvolatile memories that have traditionally been used microcontroller-based systems. features serial 2PROM memory that accessed standard parallel bus. serial architecture X84641/129 provides cost space saving replacement density parallel devices. unique parallel compatible interface also offers I/O-saving alternative serial devices that typically require three control pins communication purposes. Although X84641/129 used interface with practically 32-bit microcontroller, code provided here widely used 8051 family. Additional code found Xicor site that will implement interfaces between 8051 microcontroller family other Xicor serial devices. Xicor application notes available from using URL: http://www.xicor.com.
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X84041
Figure interface X84641/129 8051 microcontrollers
AN107-1
Xicor
AN107
TITLE(X84xxx/8031/1.0) purpose this code provide routines interface Xicor EEPROM with 8031 microcontroller. interface uses 8031's parallel connects microcontroller's strobe EEPROM's pin, strobe pin, decodes address pins A13, A14, /CS. Address space E000 FFFF used select EEPROM. EEPROM commands provided. These Single Byte Write Single Byte Read Page Write Sequential Read code performs byte write EEPROM address byte read from EEPROM address page write 22H, 33H, EEPROM addresses 100H, 101H, 102H; sequential read from EEPROM addresses 100H, 101H, 102H. CONSTANTS BYTE_ADDR 0F000H Address used single byte operation BYTE_DATA Data used single byte write operation PAGE_ADDR 0F100H Address used page operation PAGE_DATA1 data used page write operation PAGE_DATA2 data used page write operation PAGE_DATA3 data used page write operation SLIC 030H Address location SLIC INTERNAL STACK_TOP 060H Stack
CODE MAIN: lcall lcall lcall lcall ljmp #STACK_TOP byte_write byte_read page_write sequ_read SLIC Initialize stack pointer Disable interupts Write address (single byte write) Read from address (single byte read) Write 22/33/44H addresses 100/1/2H (page write) Read from addresses 100H,101H,102H (sequential read) 0000H main 0100H Reset vectors this location
AN107-2
Xicor
AN107
Name: BYTE_WRITE Description: Single byte write Function: This routine sends command sequence write single byte EEPROM Calls: rst, load_byte, nv_start, nv_poll Input: None Outputs: None Register Usage: byte_write: DPTR, #BYTE_ADDR lcall Issue reset sequence lcall load_byte Load high order address byte lcall load_byte Load order address byte #BYTE_DATA lcall load_byte Load data byte lcall nv_start Start nonvolatile write cycle lcall nv_poll Poll completion write cycle Name: PAGE_WRITE Description: Page write Function: This routine sends command sequence write three consecutive bytes Calls: rst, load_byte, nv_start, nv_poll Input: None Outputs: None Register Usage: page_write: DPTR, #PAGE_ADDR lcall Issue reset sequence lcall load_byte Load high order address byte lcall load_byte Load order address byte #PAGE_DATA1 lcall load_byte Load data byte #PAGE_DATA2 lcall load_byte Load data byte #PAGE_DATA3 lcall load_byte Load data byte lcall nv_start Start nonvolatile write cycle lcall nv_poll Poll completion write cycle
AN107-3
Xicor
AN107
Name: BYTE_READ Description: Single byte read Function: This routine sends command sequence read single byte from EEPROM Calls: rst, load_byte, rec_byte Input: None Outputs: byte read Register Usage: byte_read: DPTR, #BYTE_ADDR lcall Issue reset sequence lcall load_byte Load high order address byte lcall load_byte Load order address byte lcall rec_byte Receive data byte Name: SEQU_READ Description: Sequential read Function: This routine sends command sequence read three consecutive bytes Calls: rst, load_byte, rec_byte Input: None Outputs: last byte read Register Usage: sequ_read: DPTR, #PAGE_ADDR lcall Issue reset sequence lcall load_byte Load high order address byte lcall load_byte Load order address byte lcall rec_byte Receive data byte lcall rec_byte Receive data byte lcall rec_byte Rceive data byte Name: LOAD_BYTE Description: Loads byte EEPROM Function: This routine loads byte, first, EEPROM Calls: None Input: None Outputs: None Register Usage: load_byte: counter eight loop1: Rotate accumulator left
AN107-4
Xicor movx djnz @DPTR, loop1 Load accumulator Finish last data
AN107
Name: REC_BYTE Description: Receives byte from EEPROM Function: This routine receives byte, first, from EEPROM Calls: None Input: None Outputs: received byte Register Usage: rec_byte: counter eight register zero loop2: carry movx @DPTR data store ACC.0, zero_bit accumulator carry setb zero_bit: Load contents register accumulator Rotate accumulator left through carry Load contents accumulator register djnz loop2 Finish last data Name: Description: Reset sequence Function: This routine sends reset command sequence EEPROM Calls: None Input: None Outputs: None Register Usage: rst: movx @DPTR Read data #00H movx @DPTR, Write data movx @DPTR Read data Name: NV_START Description: Start nonvolatile write Function: This routine sends command sequence start EEPROM nonvolatile write Calls: None Input: None Outputs: None Register Usage:
AN107-5
Xicor nv_start: movx movx movx @DPTR #01H @DPTR, @DPTR Write data Read data Read data
AN107
Name: NV_POLL Description: Nonvolatile write polling Function: This routine polls completion nonvolatile EEPROM write cycle Calls: None Input: None Outputs: None Register Usage: nv_poll: loop3: movx djnz end_loop: ACC.0, end_loop loop3 @DPTR Read data Delay Delay Delay data nonvolatile cycle complete data nonvolatile cycle progress #0FFH counter
AN107-6
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