PIC16LC554 datasheet(50/96 Pages) MICROCHIP

50 / 96 page

PIC16C55X(A)

DS40143B-page 50

Preliminary

7.9

Code Protection

the

code

protection

bit(s)

have

not

been

programmed, the on-chip program memory can be

read out for veriﬁcation purposes.

7.10

ID Locations

Four memory locations (2000h-2003h) are designated

as ID locations where the user can store checksum or

other code-identiﬁcation numbers. These locations are

not accessible during normal execution but are

readable and writable during program/verify. Only the

least signiﬁcant 4 bits of the ID locations are used.

Note:

Microchip does not recommend code

protecting windowed devices.

7.11

In-Circuit Serial Programming™

The PIC16C55X(A) microcontrollers can be serially

programmed while in the end application circuit. This is

simply done with two lines for clock and data, and three

other lines for power, ground, and the programming

voltage. This allows customers to manufacture boards

with unprogrammed devices, and then program the

microcontroller just before shipping the product. This

also allows the most recent ﬁrmware or a custom

ﬁrmware to be programmed.

The device is placed into a program/verify mode by

holding the RB6 and RB7 pins low while raising the

MCLR (VPP) pin from VIL to VIHH (see programming

speciﬁcation). RB6 becomes the programming clock

and RB7 becomes the programming data. Both RB6

and RB7 are Schmitt Trigger inputs in this mode.

After reset, to place the device into programming/verify

mode, the program counter (PC) is at location 00h. A

6-bit command is then supplied to the device.

Depending on the command, 14-bits of program data

are then supplied to or from the device, depending if the

command was a load or a read. For complete details of

serial programming, please refer to the PIC16C6X/7X

Programming Speciﬁcations (Literature #DS30228).

A typical in-circuit serial programming connection is

shown in Figure 7-17.

FIGURE 7-17: TYPICAL IN-CIRCUIT SERIAL

PROGRAMMING

CONNECTION

External

Connector

Signals

To Normal

Connections

To Normal

Connections

PIC16C55X(A)

VDD

VSS

MCLR/VPP

RB6

RB7

+5V

VPP

CLK

Data I/O

VDD

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