PIC16F818/819
FIGURE 12-10:
TYPICAL IN-CIRCUIT
SERIAL PROGRAMMING
CONNECTION
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
To Normal
Connections
External
Connector
Signals
*
PIC16F818/819
+5V
0V
VDD
VSS
recent firmware or
programmed.
a
custom firmware to be
VPP
MCLR/VPP
RB6
For more information on serial programming, please refer
to the “PIC16F818/819 Flash Memory Programming
Specification” (DS39603).
CLK
Data I/O
RB7
†
RB3
RB3/PGM
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.
VDD
To Normal
Connections
* Isolation devices (as required).
RB3 only used in LVP mode.
†
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.
2004 Microchip Technology Inc.
DS39598E-page 101
MICROCHIP [ MICROCHIP ]
