PIC16F1938 Datasheet, PDF (361/452 Pages) Microchip Technology – 28/40/44-Pin Flash-Based, 8-Bit CMOS Microcontrollers

28.0 IN-CIRCUIT SERIAL
PROGRAMMING™ (ICSP™)
ICSP™ programming allows customers to manufacture
circuit boards with unprogrammed devices. Programming
can be done after the assembly process allowing the
device to be programmed with the most recent firmware
or a custom firmware. Five pins are needed for ICSP™
programming:
• ICSPCLK
• ICSPDAT
• MCLR/VPP
• VDD
• VSS
In Program/Verify mode the Program Memory, User IDs
and the Configuration Words are programmed through
serial communications. The ICSPDAT pin is a bidirec-
tional I/O used for transferring the serial data and the
ICSPCLK pin is the clock input. For more information on
ICSP™ refer to the “PIC16193X/PIC16LF193X Memory
Programming Specification” (DS41360).
28.1 High-Voltage Programming Entry
Mode
The device is placed into High-Voltage Programming
Entry mode by holding the ICSPCLK and ICSPDAT
pins low then raising the voltage on MCLR/VPP to VIHH.
Some programmers produce VPP greater than VIHH
(9.0V), an external circuit is required to limit the VPP
voltage. See Figure 28-1 for example circuit.
FIGURE 28-1:
VPP LIMITER EXAMPLE CIRCUIT
VPP
VDD
VSS
ICSP_DATA
ICSP_CLOCK
NC
1
2
3
4
5
6
RJ11-6PIN
To MPLAB^® ICD 2
R1
270 Ohm
LM431BCMX
2
3
6
7
A
A
A
A
U1 ^{K 1}
NC
NC
4
5
VREF
8
R2
R3
10k 1% 24k 1%
PIC16(L)F1938/9
RJ11-6PIN
6
5
4
3
2
1
To Target Board
Note:
The MPLAB^® ICD 2 produces a VPP volt-
age greater than the maximum VPP spec-
ification of the PIC16(L)F193X.
 2011 Microchip Technology Inc.
Preliminary
DS41574A-page 361