PIC16F785-I/ML Microchip Technology, PIC16F785-I/ML Datasheet - Page 24

• Manufacturer Part Number: PIC16F785-I/ML
• Description: IC PIC MCU FLASH 2KX14 20QFN
• Manufacturer: Microchip Technology
• Series: PIC® 16Fr

Specifications of PIC16F785-I/ML

• Core Size: 8-Bit
• Program Memory Size: 3.5KB (2K x 14)
• Core Processor: PIC
• Speed: 20MHz
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 17
• Program Memory Type: FLASH
• Eeprom Size: 256 x 8
• Ram Size: 128 x 8
• Voltage - Supply (vcc/vdd): 2 V ~ 5.5 V
• Data Converters: A/D 14x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 20-VQFN Exposed Pad, 20-HVQFN, 20-SQFN, 20-DHVQFN
• Controller Family/series: PIC16F
• No. Of I/o's: 18
• Eeprom Memory Size: 256Byte
• Ram Memory Size: 128Byte
• Cpu Speed: 20MHz
• No. Of Timers: 3
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: AC164322 - MODULE SOCKET MPLAB PM3 28/44QFN
• Connectivity: -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

PIC16F785/HV785
5.0
For the PIC16F785/HV785, once the CP bit is
programmed to ‘0’, all program memory locations read
all ‘0’s. The user ID locations and the Configuration
Word read out in an unprotected fashion. Further
programming is disabled for the entire program
memory.
Data memory is protected with its own code-protect bit
(CPD). When enabled, the data memory can still be
programmed and read using the EECON1 register.
The user ID locations and the Configuration Word can
be programmed regardless of the state of the CP and
CPD bits.
5.1
It is recommended to use the procedure in Figure 3-20
to disable code protection of the device. This sequence
will erase the program memory, data memory, Configu-
ration Word (0x2007) and user ID locations (0x2000-
0x2003). The Calibration Words (0x2008-0x2009) will
not be erased.
5.2
To allow portability of code, the programmer is required
to read the Configuration Word and user ID locations
from the hex file when loading the hex file. If Configura-
tion Word information was not present in the hex file, a
simple warning message may be issued. Similarly,
while saving a hex file, Configuration Word and user ID
information must be included. An option to not include
this information may be provided.
Specifically for the PIC16F785/HV785, the data
memory should also be embedded in the hex file (see
Section 5.3.2 “Embedding Data Memory Contents
in Hex File”).
Microchip Technology Incorporated feels strongly that
this feature is important for the benefit of the end
customer.
DS41237D-page 24
Note:
CODE PROTECTION
Disabling Code Protection
Embedding Configuration Word
and User ID Information in the Hex
File
To ensure system security, if CPD bit = 0,
Bulk Erase Program Memory command
will also erase data memory.
5.3
5.3.1
Checksum is calculated by reading the contents of the
PIC16F785/HV785 memory locations and adding up
the opcodes up to the maximum user addressable
location (e.g., 0x7FF for the PIC16F785/HV785). Any
Carry bits exceeding 16 bits are neglected. Finally, the
Configuration Word (appropriately masked) is added to
the checksum. Checksum computation for the
PIC16F785/HV785 devices is shown in Table 5-1.
The checksum is calculated by summing the following:
• The contents of all program memory locations
• The Configuration Word, appropriately masked
• Masked user ID locations (when applicable)
The 16 LSbs of this sum is the checksum.
The following table describes how to calculate the
checksum for each device. Note that the checksum
calculation differs depending on the code-protect
setting. Since the program memory locations read out
‘0’s when code-protected, the table describes how to
manipulate the actual program memory values to
simulate 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 Configuration Word and user ID
locations can always be read regardless of code-protect
setting.
Note:
Checksum Computation
CHECKSUM
Some older devices have an additional
value added in the checksum. This is to
maintain compatibility with older device
programmer checksums.
 2009 Microchip Technology Inc.