PIC TQFP-100 Breakout Board design overview

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The PIC TQFP-100 Breakout Boards support PIC32s, PIC24s, and dsPIC33 devices that come in the TQFP-100 (0.4mm pitch) PT packages. They have 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 3.3V regulated power-supply
  • External only 5V regulated supply for USB Host projects
  • Host enabled USB connector
  • X MHz primary crystal
  • 32.768 KHz secondary crystal for Real Time Clock projects
  • One power, and two user programmable LEDs
  • Reset button
  • Programing ICSP header
  • All the port pins broken out into two dual row headers

Prototype PCBs are available in the free PCB drawer.

Contents

Overview

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History/About/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.

PIC or dsPIC in TQFP100 package

File:PICTQFP100 MCU 1.jpg The microcontroller is located on the top layer and in the center of the board, making it easier to solder those 100pins. Supporting circuitry is located on the bottom layer.

One power (PWR) and two user (P1 and P3) LEDs are available for development. Also provided is a reset tactile button (RESET).

MCU support circuitry

File:PICTQFP100 supp 1.jpg

Support circuitry for the uC is on the bottom side of the board. A 3.3v,800mA voltage regulator (VREG1) is used to provide a stable power supply. The ferrite bead(L1) and 1uF capacitors (C9 and C16) provide noise suppression for the voltage regulator input. It's output is bypassed with a 1uF capacitor (C14).

The voltage regulator is powered either directly through the USB jack or through the DC-in jack.The rectifier diode (D2) prevents any current being sourced to the USB power line when both the external DC jack and the USB are connected. The ferrite bead(L1) and 1uF capacitors (C9 and C16) provide noise suppression for the voltage regulator input.

Power supply pins are decoupled with seven 0.1uF capacitors (C1-C7). The internal 2.5V voltage regulator is bypassed with a 10uF capacitor (C8).

A stable clock is provided by a XXMHz quartz crystal (X1) and two load capacitors (C10 and C1). Also provided is a secondary 32.768 KHz quartz crystal (X2) with it's load capacitors (C12 and C13) for any Real Time Clock operations.

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 2K pull-up resistor (R1). This keeps the uC in reset until the power supply voltage reaches a safe operating level. Also added is a reset button (RESET), which grounds the MCLR pin, and causes the uC to reset.

Host USB

File:PICTQFP100 USB.jpg

By placing a jumper on HOST_EN you are connecting the 5V voltage regulator (VREG2) to the USB power line for host operation. A 1uF bypass capacitor (C14) is used on the 5V line.

Warning: Do not under any circumstances connect a host device (PC) while the HOST_EN has a jumper on it, there is a high probability you will damage the host. If you plan to use the board as an "USB device only", remove the HOST_EN jumper.

Broken out Pins

File:PICTQFP100 BBSECT.jpg

PCB

File:PICTQFP100 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-C770.1uFC805
C8110uFC805
C9,C14,C15,C1641uFC805
C10-C13427pFC805
D21SOD-123
DC_IN,HOST_EN2HEADER1X2PTHM1X2
IC11PIC24/PIC32/dsPIC33TQFP100 (pitch 0.4mm)"PT"
ICSP11X05
JP1,JP222X19
L11WE-KI_0805_B
P1-PWR4,PWR,PWR6P4CHIP-LED0805
R112KR805
R4,R5,R63300R805
RESET,RESET12TACT_SWITCH_SMALL
SJ11ENVREG solder jumperSJ_2
USB1CON-USB-MINI-BUSB1CONN_USB_MINI-B
VREG11LD1117S33, 3.3VSOT223
VREG21LD1117S50, 5VSOT223
X11HC-49U
X21OSC-32.768CM309S

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!