 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
PIC12F683 Datasheet(PDF) 69 Page - Microchip Technology |
|
|
|||||||||||||||||||||||||||||
PIC12F683 Datasheet(HTML) 69 Page - Microchip Technology |
|
|
69 / 148 page  2004 Microchip Technology Inc. Preliminary DS41211B-page 67 PIC12F683 10.2 Reading the EEPROM Data Memory To read a data memory location, the user must write the address to the EEADR register and then set control bit RD (EECON1<0>), as shown in Example 10-1. The data is available, in the very next cycle, in the EEDAT register. Therefore, it can be read in the next instruction. EEDAT holds this value until another read, or until it is written to by the user (during a write operation). EXAMPLE 10-1: DATA EEPROM READ 10.3 Writing to the EEPROM Data Memory To write an EEPROM data location, the user must first write the address to the EEADR register and the data to the EEDAT register. Then the user must follow a specific sequence to initiate the write for each byte, as shown in Example 10-2. EXAMPLE 10-2: DATA EEPROM WRITE The write will not initiate if the above sequence is not exactly followed (write 55h to EECON2, write AAh to EECON2, then set WR bit) for each byte. We strongly recommend that interrupts be disabled during this code segment. A cycle count is executed during the required sequence. Any number that is not equal to the required cycles to execute the required sequence will prevent the data from being written into the EEPROM. Additionally, the WREN bit in EECON1 must be set to enable write. This mechanism prevents accidental writes to data EEPROM due to errant (unexpected) code execution (i.e., lost programs). The user should keep the WREN bit clear at all times, except when updating EEPROM. The WREN bit is not cleared by hardware. After a write sequence has been initiated, clearing the WREN bit will not affect this write cycle. The WR bit will be inhibited from being set unless the WREN bit is set. At the completion of the write cycle, the WR bit is cleared in hardware and the EE Write Complete Interrupt Flag bit (EEIF) is set. The user can either enable this interrupt or poll this bit. The EEIF bit (PIR1<7>) must be cleared by software. 10.4 Write Verify Depending on the application, good programming practice may dictate that the value written to the data EEPROM should be verified (see Example 10-3) to the desired value to be written. EXAMPLE 10-3: WRITE VERIFY 10.4.1 USING THE DATA EEPROM The data EEPROM is a high-endurance, byte address- able array that has been optimized for the storage of frequently changing information. The maximum endur- ance for any EEPROM cell is specified as Dxxx. D120 or D120A specify a maximum number of writes to any EEPROM location before a refresh is required of infrequently changing memory locations. 10.4.1.1 EEPROM Endurance A hypothetical data EEPROM is 64 bytes long and has an endurance of 1M writes. It also has a refresh param- eter of 10M writes. If every memory location in the cell were written the maximum number of times, the data EEPROM would fail after 64M write cycles. If every memory location, save one, were written the maximum number of times, the data EEPROM would fail after 63M write cycles but the one remaining location could fail after 10M cycles. If proper refreshes occurred, then the lone memory location would have to be refreshed six times for the data to remain correct. BSF STATUS,RP0 ;Bank 1 MOVLW CONFIG_ADDR ; MOVWF EEADR ;Address to read BSF EECON1,RD ;EE Read MOVF EEDAT,W ;Move data to W BSF STATUS,RP0 ;Bank 1 BSF EECON1,WREN ;Enable write BCF INTCON,GIE ;Disable INTs MOVLW 55h ;Unlock write MOVWF EECON2 ; MOVLW AAh ; MOVWF EECON2 ; BSF EECON1,WR ;Start the write BSF INTCON,GIE ;Enable INTS BSF STATUS,RP0 ;Bank 1 MOVF EEDAT,W ;EEDAT not changed ;from previous write BSF EECON1,RD ;YES, Read the ;value written XORWF EEDAT,W BTFSS STATUS,Z ;Is data the same GOTO WRITE_ERR ;No, handle error : ;Yes, continue |
Similar Part No. - PIC12F683 |
|
Similar Description - PIC12F683 |
|
|
Link URL |
| Privacy Policy |
| ALLDATASHEET.COM |
| Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
| Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
|
Family Site : ic2ic.com |
icmetro.com |
English ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
