The top side of the board is shown in the next picture:

You can see three Jumpers:

  • Power supply selection
  • Boot loader selection
  • ICSP programming interface

Last, you can find the Test Input PIN, this PIN can be used to drive the RED LED on the board.

INTERFACE LAYOUT – bottom side


In the following picture you can see all optional solder pads you can use depending of the PIC you use.





The dongle-box is shown in the following picture


This is the application scheme for Piccoletta



Click on the picture to enlarge..


Here you are the bill of materials

Componenets Value Description
C1 470n   Metallized PE Film Capacitor C050-025X075
C2, C6 0,1uF Metallized PE Film CApacitor C025-024X044
C7 0,1uF Metallized PE Film CApacitor C025-024X044 (Not mounted)
C3 10uF 18V 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
R4 10K 1% Metal film resistor (0204) 0,4 Watt
(Not mounted)
R3 3,3K 1% Metal film resistor (0204) 0,4 Watt
R1 10 Ohm 1% Metal film resistor (0204) 0,4 Watt
IC1 PIC18F2550_28DIP
L1 Led 3mm RED 15 mcd 40°

Double pin header instead of triple pin header.

Pin # 1 is not used.

pin 2–3 open: power supply from expansion board.
pin 2–3 closed: power supply from USB (5V)


J-boot Triple pin header Boot pin header
Pin 2 – 3 connected ->  A VCC is applied on the pin of PIC 
Pin 1 – 2 connected ->  GND on the pin of PIC 
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 
T 1 pin header Test pin led
T1 3 solder pad

Solder pad jumper con fori per ponticello riporta le seguenti selezioni vedi figura layout circuito Top Side
Pin 2 – 3 connected -> if a VCC is applied on the test pin the RED LEN is ON

Pin 1 – 2 connected -> RED LED on with power supply

S1 2 solder pad Used on the pin VUSB for the 3.3 V configuration.
S1 « closed
Normal power supply 5V
S1 « open (factory setting)
S2, S3 2 solder pad

Select the oscillator on the PCB
S2, S3 « closed (factory setting) the on board oscillator is selected.

S2, S3 « open the oscillator on the expansion board is selected

S4 2 solder pad Used to disconnect the PGM pin from the ICSP connector
S4 « closed (factory setting)
Normal power supply  (5V),
S4 « open
Q1 8Mhz oscillator HC49U-V
IC2 MCP1700 Microchip LDO regulator 250mA
(non mounted)
USB connector   USB-A-H


If you want to give us support or if you want the assembled and tested board, you can go to ebay at the following adress: