PIC18F2420 MICROCHIP [Microchip Technology], PIC18F2420 Datasheet - Page 88
![no-image](/images/no-image-200.jpg)
PIC18F2420
Manufacturer Part Number
PIC18F2420
Description
28/40/44-Pin Enhanced Flash Microcontrollers with 10-Bit A/D and nanoWatt Technology
Manufacturer
MICROCHIP [Microchip Technology]
Datasheet
1.PIC18F2420.pdf
(390 pages)
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Part Number:
PIC18F2420-E/SP
Manufacturer:
MICROCHIP/微芯
Quantity:
20 000
Part Number:
PIC18F2420-I/ML
Manufacturer:
MICROCHIP/微芯
Quantity:
20 000
Company:
Part Number:
PIC18F2420-I/SO
Manufacturer:
MICROCHIP
Quantity:
1 560
Part Number:
PIC18F2420-I/SO
Manufacturer:
NXP/恩智浦
Quantity:
20 000
Part Number:
PIC18F2420-I/SP
Manufacturer:
MICROCHIP/微芯
Quantity:
20 000
- Current page: 88 of 390
- Download datasheet (7Mb)
PIC18F2420/2520/4420/4520
7.6
Data EEPROM memory has its own code-protect bits in
configuration
operations are disabled if code protection is enabled.
The microcontroller itself can both read and write to the
internal data EEPROM, regardless of the state of the
code-protect configuration bit. Refer to Section 23.0
“Special Features of the CPU” for additional
information.
7.7
There are conditions when the user may not want to
write to the data EEPROM memory. To protect against
spurious EEPROM writes, various mechanisms have
been implemented. On power-up, the WREN bit is
cleared. In addition, writes to the EEPROM are blocked
during
parameter 33).
The write initiate sequence and the WREN bit together
help prevent an accidental write during brown-out,
power glitch or software malfunction.
EXAMPLE 7-3:
DS39631A-page 86
Loop
Operation During Code-Protect
Protection Against Spurious Write
the
CLRF
BCF
BCF
BCF
BSF
BSF
MOVLW
MOVWF
MOVLW
MOVWF
BSF
BTFSC
BRA
INCFSZ
BRA
BCF
BSF
words.
Power-up
EEADR
EECON1, CFGS
EECON1, EEPGD
INTCON, GIE
EECON1, WREN
EECON1, RD
55h
EECON2
0AAh
EECON2
EECON1, WR
EECON1, WR
$-2
EEADR, F
LOOP
EECON1, WREN
INTCON, GIE
DATA EEPROM REFRESH ROUTINE
External
Timer
read
period
and
(T
; Start at address 0
; Set for memory
; Set for Data EEPROM
; Disable interrupts
; Enable writes
; Loop to refresh array
; Read current address
;
; Write 55h
;
; Write 0AAh
; Set WR bit to begin write
; Wait for write to complete
; Increment address
; Not zero, do it again
; Disable writes
; Enable interrupts
PWRT
write
Preliminary
,
7.8
The data EEPROM is a high endurance, byte
addressable array that has been optimized for the
storage of frequently changing information (e.g.,
program variables or other data that are updated
often). Frequently changing values will typically be
updated more often than specification D124. If this is
not the case, an array refresh must be performed. For
this reason, variables that change infrequently (such as
constants, IDs, calibration, etc.) should be stored in
Flash program memory.
A simple data EEPROM refresh routine is shown in
Example 7-3.
Note:
Using the Data EEPROM
If data EEPROM is only used to store
constants and/or data that changes rarely,
an array refresh is likely not required. See
specification D124.
2004 Microchip Technology Inc.
Related parts for PIC18F2420
Image
Part Number
Description
Manufacturer
Datasheet
Request
R
![PIC18F-LF1XK50](/images/no-image3.png)
Part Number:
Description:
20-Pin USB Flash Microcontrollers
Manufacturer:
MICROCHIP [Microchip Technology]
Datasheet:
![PIC18F6393T-I/PT](/photos/6/81/68123/c04-066_pf_tmb.jpg)
Part Number:
Description:
PIC18F With 128-segment LCD Driver And 12-bit ADC, 8KB Flash, 768B RAM, CCP, MSS
Manufacturer:
Microchip Technology
Datasheet:
![PIC18F6493T-I/PT](/photos/6/81/68123/c04-066_pf_tmb.jpg)
Part Number:
Description:
PIC18F With 128-segment LCD Driver And 12-bit ADC, 16KB Flash, 768B RAM, CCP, MS
Manufacturer:
Microchip Technology
Datasheet:
![PIC18F8393T-I/PT](/images/manufacturer_photos/0/4/439/microchip_technology_tmb.jpg)
Part Number:
Description:
PIC18F With 192-segment LCD Driver And 12-bit ADC, 8KB Flash, 768B RAM, CCP, MSS
Manufacturer:
Microchip Technology
Datasheet:
![PIC18F8493T-I/PT](/images/manufacturer_photos/0/4/439/microchip_technology_tmb.jpg)
Part Number:
Description:
PIC18F With 192-segment LCD Driver And 12-bit ADC, 16KB Flash, 768B RAM, CCP, MS
Manufacturer:
Microchip Technology
Datasheet:
![PIC18F6585-I/L](/photos/16/12/161282/68-plcc-large-300dpi-lyrd_tmb.jpg)
Part Number:
Description:
Microcontrollers (MCU) 48KB 3328 RAM 52 I/O
Manufacturer:
Microchip Technology
Datasheet:
![PIC18F6680-I/L](/photos/16/12/161282/68-plcc-large-300dpi-lyrd_tmb.jpg)
Part Number:
Description:
Microcontrollers (MCU) 64KB 3328 RAM 52 I/O
Manufacturer:
Microchip Technology
Datasheet:
![PIC18F65K90T-I/MR](/photos/16/3/160368/qfn64_tmb.jpg)
Part Number:
Description:
32kB Flash, 2kB RAM, 1kB EE, NanoWatt XLP, LCD 64 QFN 9x9x0.9mm T/R
Manufacturer:
Microchip Technology
Datasheet:
![PIC18F65K90T-I/PT](/photos/16/3/160367/tqfp-64_tmb.jpg)
Part Number:
Description:
32kB Flash, 2kB RAM, 1kB EE, NanoWatt XLP, LCD 64 TQFP 10x10x1mm T/R
Manufacturer:
Microchip Technology
Datasheet:
![PIC18F87K90T-I/PT](/photos/40/31/403173/tqfp-80_tmb.jpg)
Part Number:
Description:
128kB Flash, 4kB RAM, 1kB EE, 16MIPS, NanoWatt XLP, LCD, 5V 80 TQFP 12x12x1mm T/
Manufacturer:
Microchip Technology
Datasheet:
![PIC18F65K90-I/MR](/photos/16/3/160368/qfn64_tmb.jpg)
Part Number:
Description:
32kB Flash, 2kB RAM, 1kB EE, NanoWatt XLP, LCD 64 QFN 9x9x0.9mm TUBE
Manufacturer:
Microchip Technology
Datasheet:
![PIC18F65K90-I/PT](/photos/16/3/160367/tqfp-64_tmb.jpg)
Part Number:
Description:
32kB Flash, 2kB RAM, 1kB EE, NanoWatt XLP, LCD 64 TQFP 10x10x1mm TRAY
Manufacturer:
Microchip Technology
![PIC18F87K90-I/PT](/photos/40/31/403173/tqfp-80_tmb.jpg)
Part Number:
Description:
128kB Flash, 4kB RAM, 1kB EE, 16MIPS, NanoWatt XLP, LCD, 5V 80 TQFP 12x12x1mm TR
Manufacturer:
Microchip Technology
![PIC1-100-JT](/images/no-image3.png)
Part Number:
Description:
SURFACE MOUNT POWER INDUCTORS
Manufacturer:
RCD [RCD COMPONENTS INC.]
Datasheet: