Datasheet

 2012 Microchip Technology Inc. Preliminary DS41652A-page 57
PIC16F527
8.16 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.
8.17 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 four bits of the ID locations and
always program the upper eight bits as ‘0’s.
8.18 In-Circuit Serial Programming™
The PIC16F527 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 ICSPCLK and ICSPDAT pins low while
raising the MCLR
(VPP) pin from VIL to VIHH (see
programming specification). ICSPCLK becomes the
programming clock and ICSPDAT becomes the
programming data. Both ICSPCLK and ICSPDAT 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
PIC16F527 Programming Specifications.
A typical In-Circuit Serial Programming connection is
shown in Figure 8-14.
FIGURE 8-14: TYPICAL IN-CIRCUIT
SERIAL PROGRAMMING
CONNECTION
External
Connector
Signals
To Normal
Connections
To Normal
Connections
V
DD
VSS
MCLR/VPP
ICSPCLK
ICSPDAT
+5V
0V
V
PP
CLK
Data
V
DD
PIC
®
Device