 2002 Microchip Technology Inc.

DS39025F-page 17

PIC16F87X

TABLE 5-1:

CHECKSUM COMPUTATION

Device

Code

Protect

Checksum*

Blank

Value

0x25E6 at 0

and max

address

PIC16F870

OFF

SUM[0x0000:0x07FFF] + CFGW & 0x3BFF

0x33FF

0xFFCD

ALL

CFGW & 0x3BFF + SUM_ID

0x3FCE

0x0B9C

PIC16F871

OFF

SUM[0x0000:0x07FFF] + CFGW & 0x3BFF

0x33FF

0xFFCD

ALL

CFGW & 0x3BFF + SUM_ID

0x3FCE

0x0B9C

PIC16F872

OFF

SUM[0x0000:0x07FFF] + CFGW & 0x3BFF

0x33FF

0xFFCD

ALL

CFGW & 0x3BFF + SUM_ID

0x3FCE

0x0B9C

PIC16F873

OFF

SUM[0x0000:0x0FFF] + CFGW & 0x3BFF

0x2BFF

0xF7CD

0x0F00 : 0xFFF

SUM[0x0000:0x0EFF] + CFGW & 0x3BFF +SUM_ID

0x48EE

0xFAA3

0x0800 : 0xFFF

SUM[0x0000:0x07FF] + CFGW & 0x3BFF + SUM_ID

0x3FDE

0xF193

ALL

CFGW & 0x3BFF + SUM_ID

0x37CE

0x039C

PIC16F874

OFF

SUM[0x0000:0x0FFF] + CFGW & 0x3BFF

0x2BFF

0xF7CD

0x0F00 : 0xFFF

SUM[0x0000:0x0EFF] + CFGW & 0x3BFF +SUM_ID

0x48EE

0xFAA3

0x0800 : 0xFFF

SUM[0x0000:0x07FF] + CFGW & 0x3BFF + SUM_ID

0x3FDE

0xF193

ALL

CFGW & 0x3BFF + SUM_ID

0x37CE

0x039C

PIC16F876

OFF

SUM[0x0000:0x1FFF] + CFGW & 0x3BFF

0x1BFF

0xE7CD

0x1F00 : 0x1FFF

SUM[0x0000:0x1EFF] + CFGW & 0x3BFF +SUM_ID

0x28EE

0xDAA3

0x1000 : 0x1FFF

SUM[0x0000:0x0FFF] + CFGW & 0x3BFF + SUM_ID

0x27DE

0xD993

ALL

CFGW & 0x3BFF + SUM_ID

0x27CE

0xF39C

PIC16F877

OFF

SUM[0x0000:0x1FFF] + CFGW & 0x3BFF

0x1BFF

0xE7CD

0x1F00 : 0x1FFF

SUM[0x0000:0x1EFF] + CFGW & 0x3BFF +SUM_ID

0x28EE

0xDAA3

0x1000 : 0x1FFF

SUM[0x0000:0x0FFF] + CFGW & 0x3BFF + SUM_ID

0x27DE

0xD993

ALL

CFGW & 0x3BFF + SUM_ID

0x27CE

0xF39C

Legend: CFGW

= Configuration Word

SUM[a:b]

= [Sum of locations a to b inclusive]

SUM_ID

= ID locations masked by 0xF then made into a 16-bit value with ID0 as the most significant nibble.

For example, ID0 = 0x1, ID1 = 0x2, ID3 = 0x3, ID4 = 0x4, then SUM_ID = 0x1234

*Checksum = [Sum of all the individual expressions] MODULO [0xFFFF]

+

= Addition

&

= Bitwise AND