PIC16F526 Datasheet, PDF (57/122 Pages) Microchip Technology – 14-Pin, 8-Bit Flash Microcontroller

8.10 Program Verification/Code
Protection
If the code protection bit has not been programmed, the
on-chip program memory can be read out for
verification purposes.
The first 64 locations and the last location (OSCCAL)
can be read, regardless of the code protection bit
setting.
The last memory location can be read regardless of the
code protection bit setting on the PIC16F526 device.
8.11 ID Locations
Four memory locations 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.
Use only the lower 4 bits of the ID locations and always
program the upper 8 bits as ‘0’s.
8.12 In-Circuit Serial Programming™
The PIC16F526 microcontroller 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 devices are placed into a Program/Verify mode by
holding the RB1 and RB0 pins low while raising the
MCLR (VPP) pin from VIL to VIHH (see programming
specification). RB1 becomes the programming clock
and B0 becomes the programming data. Both RB1 and
RB0 are Schmitt Trigger inputs in this mode.
After Reset, 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
PIC16F526 Programming Specifications.
A typical In-Circuit Serial Programming connection is
shown in Figure 8-15.
PIC16F526
FIGURE 8-15:
TYPICAL IN-CIRCUIT
SERIAL PROGRAMMING
CONNECTION
External
Connector
Signals
+5V
0V
VPP
CLK
Data
To Normal
Connections
PIC16F526
VDD
VSS
MCLR/VPP
RB1
RB0
VDD
To Normal
Connections
 2010 Microchip Technology Inc.
DS41326D-page 57