Datasheet

 2001-2013 Microchip Technology Inc. DS39598F-page 101
PIC16F818/819
12.17 In-Circuit Serial Programming
PIC16F818/819 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 (see Figure 12-10 for an example). 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.
For more information on serial programming, please refer
to the “PIC16F818/819 Flash Memory Programming
Specification” (DS39603).
FIGURE 12-10: TYPICAL IN-CIRCUIT
SERIAL PROGRAMMING
CONNECTION
Note: The Timer1 oscillator shares the T1OSI
and T1OSO pins with the PGD and PGC
pins used for programming and
debugging.
When using the Timer1 oscillator, In-Circuit
Serial Programming™ (ICSP™) may not
function correctly (high voltage or low
voltage) or the In-Circuit Debugger (ICD)
may not communicate with the controller.
As a result of using either ICSP or ICD, the
Timer1 crystal may be damaged.
If ICSP or ICD operations are required, the
crystal should be disconnected from the
circuit (disconnect either lead) or installed
after programming. The oscillator loading
capacitors may remain in-circuit during
ICSP or ICD operation.
External
Connector
Signals
To Normal
Connections
To Normal
Connections
PIC16F818/819
V
DD
VSS
MCLR/VPP
RB6
RB7
+5V
0V
V
PP
CLK
Data I/O
VDD
* * *
*
* Isolation devices (as required).
†
RB3 only used in LVP mode.
RB3
†
RB3/PGM