PIC16F628AT-E/SS Microchip Technology, PIC16F628AT-E/SS Datasheet - Page 19

• Manufacturer Part Number: PIC16F628AT-E/SS
• Description: IC,MICROCONTROLLER,8-BIT,PIC CPU,CMOS,SSOP,20PIN,PLASTIC
• Manufacturer: Microchip Technology
• Series: PIC® 16Fr

Specifications of PIC16F628AT-E/SS

• Rohs Compliant: YES
• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 16
• Program Memory Size: 3.5KB (2K x 14)
• Program Memory Type: FLASH
• Eeprom Size: 128 x 8
• Ram Size: 224 x 8
• Voltage - Supply (vcc/vdd): 3 V ~ 5.5 V
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 20-SSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: I3DBF648 - BOARD DAUGHTER ICEPIC3AC162053 - HEADER INTERFACE ICD,ICD2 18DIP
• Data Converters: -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

3.9
The programmer should be able to read data EEPROM
information from a hex file and conversely (as an
option) write data EEPROM contents to a hex file,
along with program memory information and fuse
information.
The data memory locations are logically mapped
starting at address 0x2100. The format for data
memory storage is one data byte per address location,
LSB aligned.
3.10
3.10.1
Checksum is calculated by reading the contents of the
PIC16F627A/628A/648A memory locations and adding
up the opcodes up to the maximum user addressable
location (e.g., 0x7FF for the PIC16F628A). Any carry
bits exceeding 16 bits are neglected. Finally, the Con-
figuration Word (appropriately masked) is added to the
checksum. Checksum computation for each member of
the PIC16F627A/628A/648A devices is shown in
Table 3-3.
TABLE 3-3:
© 2007 Microchip Technology Inc.
PIC16F627A
PIC16F628A
PIC16F648A
Legend: CFGW = Configuration Word
Device
Embedding Data EEPROM
Contents in Hex File
Checksum Computation
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.
*Checksum = [Sum of all the individual expressions] MODULO [0xFFFF]
+ = Addition
& = Bitwise AND
CHECKSUM
CHECKSUM COMPUTATION
Protect
Code
For example, ID0 = 0x1, ID1 = 0x2, ID3 = 0x3, ID4 = 0x4, then SUM_ID = 0x1234
OFF
OFF
OFF
ON
ON
ON
SUM[0x0000:0x03FF] + CFGW & 0x21FF
CFGW & 0x21FF + SUM_ID
SUM[0x0000:0x7FF] + CFGW & 0x21FF
CFGW & 0x21FF + SUM_ID
SUM[0x0000:0x0FFF] + CFGW & 0x21FF
CFGW & 0x21FF + SUM_ID
Preliminary
PIC16F627A/628A/648A
Checksum*
The checksum is calculated by summing the following:
• The contents of all program memory locations
• The Configuration Word, appropriately masked
• Masked ID locations (when applicable)
The Least Significant 16 bits of this sum is the
checksum.
The following table describes how to calculate the
checksum for each device.
Note:
The checksum calculation differs depend-
ing on the code-protect setting. Since the
program memory locations read out differ-
ently depending on the code-protect
setting, the table describes how to
manipulate the actual program memory
values to simulate the values that would
be read from a protected device. When
calculating a checksum, by reading a
device, the entire program memory can
simply be read and summed. The Config-
uration Word and ID locations can always
be read.
Blank
Value
1DFF
1FFE
1BFE
19FF
13FE
11FF
DS41196G-page 19
0x25E6 at 0
and Max
Address
DDCD
EBCC
DFCC
E9CD
E5CD
E7CC