PIC18F2550 Breakout Board design overview

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Prototype PCBs are available in the free PCB drawer. PIC18F2550 microcontrollers are simple to prototype with, and now we made them even simpler. This breakout board has all the support circuitry you'll need for the microcontroller, allowing you to concentrate on the rest of your project. It features:

USB and external 5V regulated power-supply USB connector X MHz crystal Reset button Programing ICSP header All the port pins broken out into a single row of headers (blade style) for easier use with standard breadboards

Contents

Overview

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History and related links

Hardware

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Click for a full size schematic image. Schematic and PCB were designed with the freeware version of Cadsoft Eagle, download the latest project files from our Google Code project page.

PIC18F2550

File:PIC18F25501 MCU 1.jpg

This board is designed around the popular and USB capable PIC18F2550 microcontroller (IC1). It can be powered either directly from USB or through the external barrel jack(DCIN) and a 5V voltage regulator (VR). The voltage regulator is bypassed by a 0.1uF capacitor (C6) on its input and a 10uF capacitor on the output (C7).

The internal 5V usb voltage regulator is bypassed by a 0.22uF capacitor (C5). while the power pin of the MCU is decoupled with a 0.1uF capacitor (C4)

An external clock is provided by a 20MHz a quartz crystal (Q1) and two load capacitors (C1 and C2).

The ICSP programing connection is brought to a header for easy development. The MCLR (RESET) programming pin is connected to the power supply through a diode (D1) and 10K pull-up resistor (R2). The diode stops the 13volt supply using during programming from damaging the rest of the circuit.

There are two LEDs on the board. One (PWR) is connected to the 5V supply, while the other (P11) is user programmable and connected to pin 11 through a current limiting 1K resistor (R1).

POWER jumper

File:PIC18F25501 PWRJMP.jpg

You can select how your board is to be powered with the POWER jumper.

POWER Jumper
Placment Source
Left External DC
Right USB

Broken out Pins

File:PIC18F25501 BBSECT.jpg

All of the MCU's pins, 5v, and GND are borken out into a single line of headers. The two pins connected to USB data lines have solder jumpers (SJ1 and SJ2) on them. If you don't plan to use USB just solder them up and they will be broken out to the header.

PCB

File:PIC18F25501 PCB1.jpg

We used the freeware version of Cadsoft Eagle to make the schematic and PCB. Download the latest designs and firmware from the project Google Code page.

  • PCB and placement notes
  • soldering advise

Partslist

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Click for a full size placement image.

PartQuantityValuePackage
C1,C2227pFC603
C4,C620.1uFC603
C510.22uFC603
C7110uFC603
D11DO323
IC11PIC18FJ2X50SOICSOIC28W
ICSP1ICSP5pin header
J11DC_BARREL_JACK_SMD_2MM
JP111X22
L11FB603
P111LED-805
PWR1LED-805
R1,R321kR603
R2110kR603
RESET1TACT_SWITCH_SMALL
SJ1,SJ22SJ
U$21HEADER1X3PTHM1X3
U$31HEADER1X5PTHM1X5
USB1CON-USB-MINI-BUSB1CONN_USB_MINI-B
VR1LD1117, 5VSOT223
X1120MhzHC-49U

Firmware

The firmware is written in C and compiled with the free Microchip C18 compiler. You can download the latest files from our Google Code project page.

  • Operating modes
  • extra software required

We used the Microchip USB stack to run the 18F2550 as a virtual serial port. Microchip's code is open but not redistributable. If you want to compile the source, download the stack from Microchip, then drag the source code into the install directory. See the detailed instructions in the PIC compiler how-to.

.inf installation

The virtual serial port (CDC) is an open standard, it should work on any modern operating system.

You don't need a driver, but you will need a .inf file to tell Windows how to use the device. A suitable .inf is included in the project archive.

Commands

Bootloader

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Source and license


Taking it further

Here's some ideas for the future:

  • List

We'll post the most recent firmware updates on our blog. You can also join the discussion in the [forum].

Get one!

You can [get one for $00], including worldwide shipping.

Your purchases at Seeed Studio keep the open source project coming, we sincerely appreciate your support!