In April 2011 I wrote about the PIC18F27J53 describing it like a monster for its capabilities, and I promise to build a development board with it.

And now this board is here!!!

The Pic18f27J53 has the following features:



Program Memory Type Flash
Program Memory (KB) 128
CPU Speed (MIPS) 12
RAM Bytes 3800
Digital Communication Peripherals 2-A/E/USART, 2-MSSP(SPI/I2C)
Capture/Compare/PWM Peripherals 7 CCP, 3 ECCP
Timers 4 x 8-bit, 4 x 16-bit
ADC 10 ch, 12-bit
Comparators 3
USB (ch, speed, compliance) 1, Full Speed, USB 2.0
Temperature Range (C) -40 to 85
Operating Voltage Range (V) 2 to 3.6
Pin Count 28
Cap Touch Channels 10



Now I’ve designed a little board that could be fit into a breadboard for fast prototype. 

This board fits in the exact form factor of DIL600 28 pin with full pin-out compatibility.

The Board is the evolution of the PICCOLETTA board . I developed this board to fit the pic18f2550, and to learn how to use the USB interface.  The PICCOLETTA PCB was modified  to support the 3,3 volt pic (27j53, 26J53 …. ) using a 3,3 volt LDO Voltage regulator ( the mcp1700) , and I also provide the possibility to mount an electronic component for EMI filter and ESD protection. Actually I haven’t it and I replace with some resistors.


  • Power supply can be selected, useing a jumper) between the USB port or an external board. 
  • Power distribution from the USB port (5V) to the external board (150 ma MAX)
  • The oscillator can be excluded using a solder pad.
  • On board led can be used as power supply led or as test ping. The configuration has to be done using a solder pad.


Enclosed into a dongle box it can be used for:

  • Security Key
  • Dongle Key
  • Security access (using the key as a rolling code)
  • Personal identification

Out from the dongle box

  • USB to RS232/TTL
  • USB to I2C
  • USB to SPI
  • TCP/UDP server (with an enc28j60)
  • Programmable I/O
  • LCD Controller Interface
  • MOTOR Controller

Finally it can be used as a developer Board.

The ICSP programming connector is present, it is compatible with pic-kit2 and 3/3. A solder pad is present on the connector to exclude PIN-6.

Fisical Dimension:

  • Length : 61,3 mm
  • Width   : 18,2 mm
  • Height  :  10,4 mm

Piccoletta2 can be programmed trough the USB.







Component Value Type
C1 220n Metallized PE Film Capacitor C025-024X044
C2, C6, C7 0,1uF Metallized PE Film Capacitor C025-024X044
C3, C8 10uF 18V Tantalium Capacitor Electrolitic Radial (5x11x2,5)
C4, C5 18pf Metallized PE Film Capacitor C050-024X044
R2, R5 10K 1% Metal film resistor (0204) 0,4 Watt
R3 3,3K 1% Metal film resistor (0204) 0,4 Watt
R1, R4 10 Ohm 1% Metal film resistor (0204) 0,4 Watt
R7, R8 22 Ohm 1% Resistor MINI_MELF-0204R (1206) 0,4 Watt
IC1 PIC18F27J53_28DIP MIL 300 DIP28
IC2 MCP1700 TO93
Microchip LDO regulator 250mA
It’s used for EMI filter and ESD protection
L1 Led 3mm red 15 mcd 40° The power led
ICSP 6 pin header ICSP PIC programming connector pin
Pin 1 Vpp « MCLR pin pic
Pin 2 Vcc «
Pin 3 Gnd «
Pin 4 PGD « PGD pin pic
Pin 5 PGC « PGC pin pic
Pin 6 PGM « PGM pin pic (could be unused)
T 1 pin header Test pin led. (active low)
R 1 pin header Button for bootloader selection. Actually it is not present in the board
JP2 2×3 pin header Power selection see
S1 2 solder pad Used to select the power supply
S2, S3 2 solder pad Used to select the oscillator S2, S3 « closed (factory setting) select the on board oscillator.
S2, S3 « open for future expansion
S4 2 solder pad S4 « close (if the pic has the PGM pin)
S4 « open disconnect the PGM pin
Q1 Oscillator 12Mhz HC49U-V
USB connector   USB-A-H


Board Layout and Setting Up


The J2 pinheader


Top view of the board (POV Ray)

Bottom view of the board (POV Ray)


Enclosed into USB dongle (POV Ray)

We have some board already soldered at low cost on ebay goto

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